Deployment circuit for pyrotechnic devices, corresponding integrated circuit, vehicle and method

Abstract

The present disclosure relates to deployment circuits for pyrotechnic devices, corresponding integrated circuits, vehicles, and methods. According to embodiments, a deployment circuit for a pyrotechnic device includes a terminal couplable to the pyrotechnic device, and a driver circuit including an electronic switch and a current limiter configured to selectively energize the pyrotechnic device. A control circuit drives the driver circuit according to a fire request signal. When the fire request signal is de-asserted, the control circuit obtains a resistance value and determines whether the resistance value falls between a first threshold and a second threshold. When the fire request signal is asserted, the control circuit starts a deployment cycle and monitors a time duration for which a current exceeds a current threshold. After stopping the deployment cycle, the control circuit obtains a second resistance value and determines whether the monitored time exceeds a time threshold and whether the second resistance value exceeds a third threshold. When both conditions are met, the control circuit signals a correct deployment.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Italian patent application No. 102024000028191, filed on December 11, 2024, which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to circuitry and methods for deploying electrically activated pyrotechnic devices such as burst tubes, pyrotechnic fuses, or pyrotechnic actuators. Background Technology

[0004] Electrically activated pyrotechnic devices serve as indispensable components for delivering large amounts of energy within a very short deployment window, and are therefore very common in safety applications. Examples of this category include, for instance, burst tubes for airbag activation, pyrotechnic fuses designed to quickly decouple electrical connections such as electric vehicle (EV) battery connections in the event of a ground fault, and pyrotechnic actuators.

[0005] In the context of security applications, various solutions have been proposed to monitor the proper connection between pyrotechnic devices and deployment circuitry. For example, such solutions are disclosed in U.S. Patent Application Publication Nos. US 2018 / 0029554 A1 and US 2019 / 0302162 A1. These solutions assume that the pyrotechnic device typically has a resistance within a given tolerance range. Accordingly, by determining whether the resistance between the terminals coupled to the pyrotechnic device falls within a lower threshold and an upper threshold, the deployment circuitry can determine whether the pyrotechnic device is correctly coupled to the deployment circuitry.

[0006] Conversely, the actual deployment of pyrotechnic devices is typically detected via auxiliary sensors. For example, U.S. Patent Publication No. 10,029,640 B2 or JP 2002 / 144994 A discloses such a solution in the context of airbag deployment detection.

[0007] Furthermore, Italian patent application IT102024000002019, filed on February 1, 2024, discloses a solution for detecting the deployment of pyrotechnic devices by monitoring their terminal voltage.

[0008] For example, Figure 1 and Figure 2An exemplary deployment circuit 100 is shown. The deployment circuit 100 includes a first terminal 122a and a second terminal 122b configured to be coupled to an electrically activated pyrotechnic device 101. For example, the pyrotechnic device 101 may be an airbag inflator, a seatbelt pretensioner initiator, a pyrotechnic switch, or a pyrotechnic fuse. Furthermore, the deployment circuit 100 includes a driver circuit configured to selectively energize the pyrotechnic device 101. Typically, the driver circuit is configured to apply a given voltage V... PYRO The current I applied to terminals 122a and 122b or controlled via terminals 122a and 122b is applied to or controlled by the current I supplied to them. PYRO In fact, from an electrical perspective, the pyrotechnic device 101 for ignition mainly represents a resistive load.

[0009] For example, in Figure 1 In this configuration, the driver circuit is configured to selectively couple terminals 122a and 122b to the supply voltage VIN. For this purpose, the driver circuit may include a first terminal 121 and a second terminal 123 (e.g., representing ground GND). The first terminal 121 is configured to receive the supply voltage VIN. For example, the voltage VIN may be provided by a vehicle battery, including, for example, a pyrotechnic device 101 associated with a corresponding airbag of the vehicle. Alternatively, the supply voltage VIN may be supplied by one or more capacitors (…). Figure 1 (Not shown in the image) is provided. For example, (one or more) such capacitors can be charged by an additional electronic converter such as a boost or buck converter.

[0010] For example, in Figure 1 In this circuit, the driver circuit includes a first electronic switch 104 configured to couple terminal 122a to terminal 121 according to a first drive signal 192a, or a second electronic switch 103 configured to couple terminal 122b to terminal 123 according to a second drive signal 192b. For example, switches 103 and 104 may be field-effect transistors (FETs), such as metal-oxide-semiconductor field-effect transistors (MOSFETs). For example, each switch 103 and 104 may be a normally open switch, such as a depletion-type MOSFET, which closes in response to the receipt of the asserted drive signal (192b or 192a).

[0011] Accordingly, when terminals 122a and 122b are coupled to the supply voltage, for example, when electronic switches 103 and 104 are closed, voltage VIN is also applied to the pyrotechnic device 101 (ignoring possible parasitic resistance, such as the parasitic resistance of the cables), that is, the voltage V at the pyrotechnic device 101 is... PYRO Corresponding to the voltage VIN, the current I PYRO The flames flow through the pyrotechnic device 101.

[0012] On the contrary, Figure 2In this embodiment, the driver circuit is configured to selectively apply current to terminals 122a and 122b. For example, in the considered embodiment, the driver circuit includes a current source or current limiter 102 configured to set or limit the current supplied via terminals 122a and 122b, respectively.

[0013] For example, in Figure 2 In this circuit, the driver circuitry includes a current source or current limiter 102 coupled between terminals 122a and 121. The current source or current limiter 102 can be configured to set a requested current or a maximum current according to a reference signal 193. For example, circuit 102 can be implemented using a field-effect transistor (FET). For example, this FET can correspond to the output stage of a current mirror.

[0014] In this case, the driver circuit may also include Figure 1 The first electronic switch 104 or the second electronic switch 103 shown. For example, in Figure 2 In the driver circuit, an electronic switch 103 is configured to couple terminal 122b to terminal 123 according to a second drive signal 192b. Accordingly, in Figure 2 In this configuration, the driver circuit is configured to regulate or at least limit the current I flowing through the pyrotechnic device 101. PYRO .

[0015] For example, current source 102 can be used to measure current flowing through electronic switches 104 or 103 (see...). Figure 1 The current v is such as the current of the driver circuit, wherein the driver circuit includes a closed-loop control circuit configured to regulate the measured current to the desired value by, for example, selectively coupling terminals 122a and 122b to voltage VIN or decoupling terminals 122a and 122b from voltage VIN via electronic switches 104 and 103.

[0016] Conversely, the driver circuit can use the measured current I PYRO When the value is less than the maximum requested value, terminals 122a and 122b are coupled to the voltage VIN and the measured current I. PYRO The current limiter 102 is implemented by decoupling terminals 122a and 122b from the voltage VIN when the current exceeds the maximum requested value. In various embodiments, the comparison may also include hysteresis, i.e., the driver circuit may be configured to apply a hysteresis condition to the measured current I. PYRO When the value exceeds the maximum requested value, decouple terminals 122a and 122b from the voltage VIN, and decouple the measured current I... PYRO When the value is less than the minimum requested value, terminals 122a and 122b are coupled to voltage VIN.

[0017] Accordingly, the deployment circuit 100 also includes a control circuit 114 configured to generate one or more of signals 192a, 192b, and 193 in response to an ignition or deployment request signal 191. For example, signal 191 may be generated by an external deployment control circuit.

[0018] For example, regarding Figure 1 The circuit shown, in response to the detection of a deployment request signal 191 indicating an ignition request, for example, when signal 191 is asserted, control circuit 114 asserts (high-side) drive signal 192a and (low-side) drive signal 192b.

[0019] On the contrary, regarding Figure 2 The circuit shown, in response to detecting a deployment request signal 191 indicating an ignition request, for example, when signal 191 is asserted, control circuit 114 asserts (low-side) drive signal 192b. If current source or limiter 102 is configurable, control circuit 114 can also generate signal 193 to reduce current I... PYRO Set to the requested value or limit it to the maximum value. Alternatively, control circuit 114 can be configured to measure current I. PYRO And based on the measured current, drive electronic switch 103 or 104 (e.g., by implementing current I). PYRO Closed-loop control, or by comparing it with one or more thresholds (such as maximum current and minimum current).

[0020] Specifically, according to document IT102024000002019, the deployment circuit includes a processing circuit 111 configured to receive the voltages at terminals 122a and 122b and generate a processed signal 195, wherein the voltages at terminals 122a and 122b are the voltage V across the pyrotechnic device 101. PYRO The processing circuit 111 can be any analog or digital circuit. For example, in Figure 1 The diagram shows an analog-to-digital converter (ADC) 110 coupled between the processing circuit 111 and terminals 122a and 122b of the pyrotechnic device 101.

[0021] Furthermore, comparator 112 is configured to generate deployment status signal 190a by comparing the processed signal 195 (analog or digital) with a threshold 196. For example, after determining that the processed signal 195 exceeds the (analog or digital) threshold 196, comparator 112 can assert the deployment status signal 190a, for example, by setting signal 190a high. Document IT102024000002019 proposes various processing operations that can be implemented by processing circuitry 111. For example, signal 195 can indicate the unit resistivity energy i2t supplied to pyrotechnic device 101, and can be, for example, resistance, voltage, or unit resistivity energy.

[0022] Specifically, such as Figure 1 As shown, control circuit 114 can be coupled to timer circuit 115. In response to receiving ignition request signal 191, control circuit 114 initiates the deployment of the pyrotechnic device (as per [reference]). Figure 1 or Figure 2 (As described). It resets the timer circuit 115 by sending a reset signal 187. The control circuit 114 is also configured to repeatedly compare the ongoing time 188 with a time threshold tTIMEOUT indicating the maximum time the deployment operation can take during deployment operations. Upon determining that time 188 has exceeded the time threshold tTIMEOUT, the control circuit 114 interrupts the deployment of the pyrotechnic device. Accordingly, the control circuit 114 is configured to drive the pyrotechnic device 101 to a given maximum time in response to the ignition request signal 191.

[0023] in this regard, Figure 3 The current I of the pyrotechnic device 101 during the deployment cycle starting at time t0 and ending at time t2 (i.e., the time between time t0 and t2 can correspond to time tTIMEOUT) is shown. PYRO Voltage V PYRO and resistance R PYRO As time goes by.

[0024] As previously stated, during the deployment cycle, the drive circuit supplies voltage V to the pyrotechnic device 101 via terminals 122a and 122b. PYRO and current I PYRO Specifically, due to parasitic inductance or capacitance, the voltage and current supplied to the pyrotechnic device 101 typically do not increase in a step-like manner, but rather as... Figure 3 The increase is shown in the diagram. Furthermore, in... Figure 2 In the embodiment shown, the current I PYRO It can be limited to a given maximum value.

[0025] In this respect, as previously stated, the pyrotechnic device 101 essentially represents a resistive load, thus the voltage V PYROand current I PYRO Based on Ohm's law, that is, V PYRO =I PYRO ∙R PYRO , where R PYRO Corresponding to the resistor of the pyrotechnic device 101.

[0026] Specifically, during the deployment cycle, the resistor R PYRO Initially, it remains essentially constant, as in an undeployed pyrotechnic device. During this period, the chemical reaction that would ignite the pyrotechnic device has not yet been triggered, indicating the presence of the deployed current I. PYRO The structure and composition of the pyrotechnic device initiator remain unchanged as it flows through it.

[0027] Subsequently, at time t1, the pyrotechnic device 101 ignites. Specifically, ignition causes resistance R to... PYRO The sudden increase. Accordingly, the deployment circuit 100 of document IT102024000002019 is configured to increase the resistor R. PYRO This increased detection confirms the successful deployment of the pyrotechnic device and asserts a good ignition signal 190a.

[0028] Specifically, document IT102024000002019 discloses the resistor R. PYRO You can use a dedicated current measurement IMEAS or the current I used during deployment. PYRO To measure.

[0029] For example, when using the measuring current IMEAS, the deployment circuit 100 can be configured to provide a (small) measuring current IMEAS via terminals 122a and 122b and evaluate the value of signal 194. In fact, when the pyrotechnic device 101 is in an undeployed condition, the resistance R... PYRO It should have a first value R PYRO1 Specifically, this first value R PYRO1 It should be within a given predetermined range. For example, in various known solutions, similar measurements are used to periodically determine whether the pyrotechnic device 101 is correctly coupled to terminals 122a and 122b. Specifically, in the absence of an ignition request, the deployment circuit 100 can be configured to periodically: apply a measuring current IMEAS to terminals 122a and 122b via a drive circuit; and monitor the voltage V via a processing circuit 112. PYRO And determine the indicating resistor R PYRO The signal 195; and whether the signal 195 is between the lower threshold and the upper threshold is determined by comparator 112.

[0030] For example, in this case, after determining that signal 195 is not within the threshold, deployment circuit 100 can signal the malfunction of pyrotechnic device 101.

[0031] Accordingly, once the deployment cycle is complete, the deployment circuit 100 can be configured to measure the resistance R via the current measuring IMEAS. PYRO It then determines whether signal 195 exceeds threshold 196. Specifically, in this case, when signal 195 exceeds threshold 196, the pyrotechnic device 101 has been correctly deployed.

[0032] However, the (higher) deployment current I during the deployment cycle PYRO It can also be used to determine the resistance R. PYRO The increase. In fact, as Figure 3 As shown, when the pyrotechnic device 101 is deployed, the voltage V PYRO The voltage increases significantly at time t2. In this regard, document IT102024000002019 discloses a method for analyzing only the voltage V. PYRO For example, using the detection voltage V PYRO Increase or analysis of voltage V PYRO and current I PYRO Both, for example, use the sensing resistor R PYRO The addition of [a certain element] is used to detect various deployed solutions.

[0033] The inventors have observed that the solution disclosed in document IT102024000002019 may incorrectly detect the deployment of pyrotechnic device 101 in a given situation. Summary of the Invention

[0034] In view of the above, the purpose of the various embodiments is to provide an improved solution that provides more reliable detection of the deployment of pyrotechnic devices.

[0035] According to one or more embodiments, this objective can be achieved by means of a deployment circuit for a pyrotechnic device having the unique elements specifically set forth in the appended claims. Furthermore, the embodiments relate to related integrated circuits, vehicles, and methods.

[0036] The scope of protection is defined by the appended claims, which form part of the technical teachings described herein.

[0037] As mentioned above, various embodiments of this disclosure relate to deployment circuitry for pyrotechnic devices. In various embodiments, the deployment circuitry, for example, integrated into an integrated circuit, includes positive and negative terminals configured to receive a supply voltage, and first and second terminals configured to be coupled to the pyrotechnic device.

[0038] In various embodiments, the driver circuit is configured to selectively energize the pyrotechnic device. For this purpose, the driver circuit may include at least one electronic switch and at least one current limiter, wherein the at least one electronic switch is configured to selectively couple a first terminal and a second terminal to a positive terminal and a negative terminal in response to an assertion of a deployment control signal, and the at least one current limiter is configured to limit the current supplied via the first terminal and the second terminal to a maximum value. For example, in various embodiments, the at least one electronic switch includes an electronic switch coupled between the second terminal and the negative terminal, and the at least one current limiter includes a current limiter coupled between the positive terminal and the first terminal.

[0039] In various embodiments, the control circuitry is configured to control the driver circuitry based on an ignition request signal. Specifically, in various embodiments, in response to determining that the ignition request signal has been deasserted, the control circuitry obtains a first value indicating the resistance between the first and second terminals. Next, the control circuitry determines whether the first value falls between a first threshold and a second threshold, wherein the second threshold is greater than the first threshold. In response to determining that the first value is not between the first and second thresholds, the control circuitry signals an error. In various embodiments, the control circuitry is configured to periodically repeat these operations. In various embodiments, the first threshold corresponds to the minimum resistance value of a correctly coupled, undeployed pyrotechnic device, and the second threshold corresponds to the maximum resistance value of a correctly coupled, undeployed pyrotechnic device.

[0040] In various embodiments, in response to the determination that an ignition request signal has been asserted, the control circuit initiates a deployment cycle by setting the maximum value to a first maximum value and asserting a deployment control signal. Subsequently, the control circuit stops the deployment cycle after a given time period by deasserting the deployment control signal.

[0041] Specifically, in various embodiments, the control circuit is configured to monitor a value indicating the time during which the current supplied via the first and second terminals is greater than a current threshold during the deployment cycle. Furthermore, once the deployment cycle has stopped, the control circuit obtains a second value indicating the resistance between the first and second terminals.

[0042] Specifically, in various embodiments, the control circuitry determines whether the monitored value indicates that the time has exceeded a time threshold, and whether a second value exceeds a third threshold, wherein the third threshold is greater than the second threshold. For example, the third threshold may correspond to the minimum resistance value of a properly coupled, deployed pyrotechnic device.

[0043] Specifically, in various embodiments, in response to determining that the monitored value indicates that the time exceeds a time threshold and the second value exceeds a third threshold, the control circuit signals to notify the correct deployment of the pyrotechnic device.

[0044] Conversely, when the monitored value indicates that the time is not greater than a time threshold or the second value is not greater than a third threshold, the control circuit can perform different operations.

[0045] For example, in various embodiments, the control circuit initiates a new deployment cycle when it determines that the monitored value indication time exceeds a time threshold and the second value is not greater than a third threshold. Alternatively, the control circuit can also determine whether the second value is greater than a first threshold. In this case, the control circuit can initiate a new deployment cycle in response to determining that the monitored value indication time is greater than the time threshold, the second value is greater than the first threshold, and the second value is not greater than the third threshold. Conversely, if the monitored value indication time exceeds the time threshold and the second value is not greater than the first threshold, the control circuit can signal an error.

[0046] Conversely, in various embodiments, in response to determining that the monitored value indicates a time not greater than a time threshold and a second value greater than a third threshold, the control circuit can signal an error or begin a new deployment cycle.

[0047] In various embodiments, the control circuit may use an electronic switch for deploying the pyrotechnic device to measure resistance. Conversely, in other embodiments, the deployment circuit includes a first current limiter coupled between a positive terminal and a first terminal, wherein the first current limiter is configured to limit the current flowing through the first current limiter to a maximum value. Furthermore, the deployment circuit includes a second current limiter and an electronic switch, wherein the electronic switch is configured to selectively couple the second current limiter between a second terminal and a negative terminal according to a measurement control signal, wherein the second current limiter is configured to limit the current flowing through the second current limiter to a second maximum value, wherein the second maximum value is less than the first maximum value. Accordingly, in this case, the control circuit can obtain a value indicating the resistance between the first and second terminals by setting the maximum value of the first current limiter to the second maximum value, asserting the measurement control signal, and obtaining a value indicating the voltage at the first and second terminals. For example, the value indicating the resistance between the first and second terminals may correspond to a value indicating the voltage at the first and second terminals, a value indicating the voltage at the first and second terminals divided by a predetermined value, or a value indicating the voltage at the first and second terminals divided by a value indicating the current supplied via the first and second terminals.

[0048] In various embodiments, the deployment circuitry includes a current measurement circuit configured to obtain a value indicating the current flowing through an electronic switch coupled between a second terminal and a negative terminal. For example, in various embodiments, the electronic switch coupled between the second terminal and the negative terminal is an n-channel FET. In this case, the current measurement circuitry may include an additional n-channel FET and a regulator circuitry having a gate terminal coupled to the n-channel FET and a gate terminal receiving a deployment control signal. The regulator circuitry is configured to vary the current flowing through the additional n-channel FET until the drain-source voltage of the additional n-channel FET corresponds to the drain-source voltage of the n-channel FET. In fact, in this way, the current measurement circuitry can be configured to obtain a value indicating the current flowing through the electronic switch by monitoring the current flowing through the additional n-channel FET.

[0049] In various embodiments, the control circuit may monitor time via a counter. For example, when the current supplied via the first and second terminals during a deployment cycle is greater than a current threshold, the control circuit may increment the counter value. Accordingly, in this case, the control circuit can determine whether the monitored value indicates that the time is greater than a time threshold by determining whether the counter value is greater than a counting threshold. Attached Figure Description

[0050] Embodiments of this disclosure will now be described with reference to the accompanying drawings, which are provided by way of non-limiting example only, and in which:

[0051] The features and advantages of the present invention will become clear from the following detailed description of practical embodiments thereof, which are illustrated by way of non-limiting example in the accompanying drawings, in which:

[0052] Figure 1 A first example of a deployment circuit for a pyrotechnic device is shown;

[0053] Figure 2 A second example of a deployment circuit for a pyrotechnic device is shown;

[0054] Figure 3 It shows Figure 1 and Figure 2 Exemplary waveforms of the deployment circuit during the deployment cycle;

[0055] Figure 4 A deployment circuit according to this disclosure is shown;

[0056] Figure 5 It shows the use of Figure 4 Examples of driver circuits, voltage measurement circuits, and current measurement circuits for the deployment circuit;

[0057] Figure 6 It shows Figure 4 An example of the operation of the control circuit of the deployment circuit;

[0058] Figure 7 It shows Figure 5 Exemplary waveforms of the deployment circuit during the deployment cycle; and

[0059] Figure 8 It shows the use of Figure 4 Another embodiment of the current measurement circuit of the deployment circuit. Detailed Implementation

[0060] In the following description, various specific details are set forth to enable a thorough understanding of the embodiments. Embodiments may be provided without one or more of these specific details, or may be provided with other methods, components, materials, etc. In other instances, known structures, materials, or operations are not shown or described in detail so as not to obscure various aspects of the embodiments.

[0061] References to "embodiment" or "an embodiment" within the framework of this description are intended to indicate that a particular configuration, structure, or feature described in connection with that embodiment is included in at least one embodiment. Therefore, phrases such as "in an embodiment" or "in one embodiment" appearing in various places throughout this description do not necessarily refer to the same embodiment. Furthermore, specific configurations, structures, or features may be combined in any suitable manner in one or more embodiments.

[0062] The references used herein are provided for convenience only and therefore do not define the scope or range of protection of the embodiments.

[0063] The following description Figures 4 to 8 In the middle, it has been referenced Figures 1 to 3 The described parts, elements, or components are designated by the same reference numerals used previously in these figures. Descriptions of these elements have already been made and will not be repeated below to avoid burdening this detailed description.

[0064] As mentioned above, various embodiments of this disclosure provide solutions for deploying pyrotechnic devices.

[0065] Specifically, the inventors have observed that the solution disclosed in document IT102024000002019 can detect that the pyrotechnic device 101 has been deployed. However, the deployment circuit may malfunction when the connection to the pyrotechnic device is damaged during the deployment cycle.

[0066] For example, in the event of an accident, the cable coupling the pyrotechnic device 101 to the deployment circuit may be damaged. For instance, this could mean that the cable coupling the pyrotechnic device 101 to the deployment circuit is broken, thus creating an open circuit between terminals 122a and 122b. However, the cable coupling the pyrotechnic device 101 to the deployment circuit could also create a short circuit between terminals 122a and 122b.

[0067] For example, in the former case, the circuit in document IT102024000002019 can signal incorrect deployment because of the resistance value R. PYRO And similarly, voltage V PYRO The value increases above the threshold of 196 during the deployment cycle. Conversely, the latter case will not be detected because the resistance value R... PYRO And similarly, voltage V PYRO If the threshold is kept below 196, a new deployment cycle will be triggered.

[0068] The following section describes a solution for the proper detection of the deployment of pyrotechnic devices 101, such as burst tubes, pyrotechnic fuses, or pyrotechnic actuators.

[0069] Figure 4 An embodiment of the deployment circuit 20 according to this disclosure is shown. Specifically, the deployment circuit 20 includes a first terminal 122a and a second terminal 122b configured to be coupled to a pyrotechnic device 101. The deployment circuit 20 also includes a driver circuit 200 configured to supply electrical power to terminals 122a and 122b. For this purpose, the driver circuit 200 may include a configuration for receiving a supply voltage V. IN The first (positive) terminal 121 and the second (negative) terminal 123. For example, terminal 123 can represent ground.

[0070] For example, such as regarding Figure 1 As disclosed, in various embodiments, the driver circuit 200 can be configured to couple terminals 122a and 122b to the supply voltage V. IN This allows current I to be supplied via terminals 122a and 122b. PYRO In various embodiments, the driver circuit 200 may further include components configured to drive current I PYRO A current limiter that restricts current to its maximum value.

[0071] In the considered embodiments, deployment circuit 20 further includes control circuit 202 configured to control the operation of driver circuit 200 via one or more control signals CTRL. For example, to initiate a deployment cycle, control circuit 202 may set control signal CTRL to indicate that energy should be supplied to pyrotechnic device 101. Accordingly, in various embodiments, control circuit 202 also receives an ignition request signal REQ indicating a request for deployment of pyrotechnic device 101.

[0072] like Figure 4 As shown in various embodiments, deployment circuit 20 also includes a current sensor 206 configured to generate an indication of a current I supplied via terminals 122a and 122b. PYRO (For example, a signal MI proportional to it). In various embodiments, the deployment circuit 20 also includes a voltage sensor 204 configured to generate a voltage V at indicating terminals 122a and 122b. PYRO (For example, the signal MV that is proportional to it).

[0073] Figure 5 An embodiment of the driver circuit 200 is shown. Specifically, in the considered embodiment, the driver circuit 200 is configured to selectively enable current flowing through the pyrotechnic device 101.

[0074] Specifically, in the considered embodiment, the driver circuit 200 includes one or more electronic switches configured to selectively couple terminals 122a and 122b to the voltage V (received at terminals 121 and 123) in response to an assertion of the determination signal DEP_CMD. IN For example, in the considered embodiment, the driver circuit 200 includes one or more electronic switches having a current path coupled in series with terminals 122a and 122b between terminals 121 and 123.

[0075] For example, in the considered embodiment, the current path of electronic switch 2002a is (e.g., directly) coupled between terminals 122b and 123, wherein electronic switch 2002a closes in response to an assertion of the determination signal DEP_CMD. For example, in the considered embodiment, electronic switch 2002a is a field-effect transistor, such as an n-channel FET with its drain terminal coupled to terminal 122b, its source terminal coupled to terminal 123, and its gate terminal receiving the signal DEP_CMD. Additionally or alternatively, driver circuitry 200 may include an electronic switch having a current path coupled between terminals 121 and 122a, wherein the electronic switch closes when the signal DEP_CMD is asserted.

[0076] In various embodiments, the driver circuit 200 also includes one or more current limiters coupled in series with terminals 122a and 122b. For example, in the considered embodiment, current limiter 2000a is coupled between terminals 121 and 122a. Additionally or alternatively, the current limiter may be coupled between terminals 122b and 123.

[0077] In various embodiments, the maximum value of one or more current limiters, such as current limiter 2000a, may be settable via the signal IMAX. For example, the current limiter may be implemented with the output branch of a current mirror, wherein the current in the input branch of the current mirror is settable, for example, via a current digital-to-analog converter (IDAC), or via a plurality of selectively enabled current limiters.

[0078] Accordingly, in the considered embodiment, control circuit 202 can assert the signal DEP_CMD to request current to be supplied via terminals 122a and 122b, wherein current I PYRO The maximum value can be set via the IMAX signal.

[0079] Specifically, in various embodiments, the current limiter 2000a is configured to use (at least) two maximum values ​​I. DEP and I MEAS For example, in this case, the signal IMAX could be a binary signal that selects one of two maximum values. Specifically, in various embodiments, the maximum value I is used when the pyrotechnic device 101 should be deployed. DEP The maximum value I MEAS Used to measure the resistance between terminals 122a and 122b. Accordingly, in various embodiments, the current I can be measured via signal IMAX. PYRO The maximum value is set to value I. DEP Or I MEAS It also asserts the signal DEP_CMD to generate current flow.

[0080] Figure 5 Alternative embodiments are also shown, wherein the driver circuit 200 includes an additional current limiter 2000b and an additional electronic switch 2002b, which are coupled in series between terminals 122b and 123. Specifically, in the considered embodiment, the current limiter 2000b uses I... MEAS The maximum value is determined, and the electronic switch 2002b closes in response to the assertion of the determination signal MEAS_CMD.

[0081] Accordingly, in the considered embodiment, the signal DEP_CMD can be used to request the execution of a deployment cycle. Specifically, in response to the signal DEP_CMD, the current limiter 2000a can use a maximum value I. DEPAnd electronic switch 2002a can be closed. For example, for this purpose, signal DEP_CMD can enable the first current limiter within current limiter 2002a, where the first current limiter uses the maximum value I. DEP .

[0082] Conversely, the MEAS_CMD signal can be used to request a measurement cycle. Specifically, in response to the MEAS_CMD signal, the current limiter 2000a can use the maximum value I. MEAS And electronic switch 2002b can be closed. For example, for this purpose, signal MEAS_CMD can enable a second current limiter within current limiter 2002a, wherein the second current limiter uses a maximum value I. MEAS Accordingly, in the considered embodiment, the current I PYRO Both the upper branch (between terminals 121 and 122a) and the lower branch (between terminals 122b and 123) are limited to a maximum value of I. MEAS Specifically, the additional current limiter 2000b and the additional electronic switch 2002b have the advantage of being able to detect various types of connection errors by monitoring the voltage at terminals 122a and 122b.

[0083] Figure 5 An embodiment of voltage measurement circuit 204 is also shown; however, other solutions may also be used to measure the voltage V at terminals 122a and 122b. PYRO For example, in Figure 5 In the measurement circuit 204, there is an analog-to-digital converter (ADC) 2040 (e.g., differential) configured to generate a digital sample MV by sampling the voltages at terminals 122a and 122b. However, the ADC 2040 can also sample the voltages at terminals 122a and 122b and calculate the difference. Therefore, other ADC circuits can also be used to generate the voltage V at terminals 122a and 122b. PYRO The sample MV.

[0084] Figure 5 An embodiment of the current measurement circuit 206 is also shown; however, other solutions may also be used to measure the current I supplied via terminals 122a and 122b. PYRO Specifically, when using a current limiter 2000a coupled between terminals 121 and 122a, the current sensor 206 should measure the current flowing between terminals 122b and 123. For example, this allows determination of whether one of terminals 122a and 122b is short-circuited to ground. Additionally or alternatively, the current sensor 206 can be configured to measure the current flowing between terminals 121 and 122a.

[0085] For example, in various embodiments, current sensor 206 is configured to apply a current proportional to the current flowing through electronic switch 2002a to resistor 2060, such as a resistor. Accordingly, in the considered embodiments, the voltage at resistor 2060 is proportional to the current flowing through electronic switch 2002a. Accordingly, in the considered embodiments, current sensor 206 may include (e.g., differential) analog-to-digital converter 2062 configured to generate a digital sample MI by sampling the voltage at resistor 2060. However, analog-to-digital converter 2062 may also sample the voltage at the terminals of resistor 2060 and calculate the difference. Therefore, other analog-to-digital conversion circuitry can be used to generate the sample MI of the voltage at resistor 2060.

[0086] In its simplest form, resistor 2060 can be coupled in series with electronic switch 2002a. However, this could also affect the current flow through pyrotechnic device 101. Accordingly, in various embodiments, current sensor 206 includes an additional n-channel FET 2064 and a regulator circuit configured to vary the current flowing through FET 2064 until the voltage between the drain and source terminals of FET 2064 corresponds to the voltage between the drain and source terminals of FET 2002a. In fact, in this case, the current I flowing through FET 2064 is based on the ratio N between FET 2002a and 2064. MON With the current I flowing through FET2002a PYRO Proportional. For example, in various embodiments, transistor 2002a has a ratio of N=1000 to transistor 2064, that is, I MON =I PYRO / 1000.

[0087] For example, in the considered embodiment, the regulator circuit is implemented using a FET 2068, which essentially acts as a variable current source, and an operational amplifier 2066. The operational amplifier 2066 has a first input terminal coupled to the drain terminal of the FET 2002a and a second input terminal coupled to the drain terminal of the FET 2064, wherein the output of the operational amplifier 2066 drives the gate of the FET 2068. For example, when the FET 2068 is an n-channel FET, the first input terminal of the operational amplifier 2066 can correspond to the positive / non-inverting input terminal, and the second input terminal of the operational amplifier 2066 can correspond to the negative / inverting input terminal. Conversely, for the p-channel FET 2068, the connections are reversed.

[0088] Accordingly, in the considered embodiment, FET 2068 is properly biased and resistor 2060 is coupled in series with FETs 2068 and 2064 (the current path). For example, in the considered embodiment, the drain terminal of the n-channel FET 2068 is coupled to the bias voltage via resistor 2060, for example, the drain terminal of the n-channel FET 2068 is coupled to terminal 121 via resistor 2060. Conversely, the source terminal of the n-channel FET 2068 is coupled to the drain terminal of FET 2064.

[0089] In various embodiments, resistor 2060 and voltage ADC 2062 can also be replaced by a current analog-to-digital converter. For example, the drain terminal of n-channel FET 2068 can be coupled to the input of the current analog-to-digital converter, so that the current analog-to-digital converter can input current I. MON Sampling is performed to provide the signal MI.

[0090] In various embodiments, voltage analog-to-digital converters 2040 and 2062 may also be implemented using the same analog-to-digital converter, for example, with an input multiplexer. Additionally or alternatively, analog-to-digital converters 2040 and 2062 may be integrated into control circuitry 202. For example, in this case, control circuitry 202 may be implemented using a microcontroller that includes one or more analog-to-digital converters. In this case, a current analog-to-digital converter may be used to set the maximum value IMAX, which can be implemented using the current analog-to-digital converter of the microcontroller. Similarly, a current analog-to-digital converter may be used to control the current I... MON Sampling can be performed using a microcontroller's current-to-analog converter. In various embodiments, the operation of the control circuit 202 can also be implemented via analog processing circuitry; that is, the digital-to-analog converter and the analog-to-digital converter are purely optional.

[0091] Those skilled in the art will recognize that, when the optional current limiter 2000b and the optional electronic switch 2002b are also used, Figure 5 The current measurement circuit 206 shown monitors the current I only during the deployment cycle when the signal DEP_CMD is asserted. PYRO However, if needed, different or multiple current measurement circuits 206 can be used to monitor the current I during both the deployment and measurement cycles. PYRO .

[0092] Figure 6 An embodiment of the operation of the control circuit 202 according to this disclosure is shown. Figure 6The operations shown can be implemented in any suitable manner, including hardware implementation, software implementation, or a combination thereof. For example, in various embodiments, control circuitry 202 is implemented using a microcontroller including a microprocessor. In this case, the operations can be implemented via software instructions that cause the microprocessor to perform the operations when executed by the software instructions. Alternatively, the operations can be implemented via a finite state machine (FSM) implemented with hardware sequential logic circuitry. Alternatively, the operations can also be implemented at least partially via analog circuitry. Therefore, in general, any suitable analog or digital circuitry can be used to implement the operations of control circuitry 202.

[0093] Specifically, after starting step 1000, control circuit 202 proceeds to step 1002, where control circuit 202 determines the resistance R between indicator terminals 122a and 122b. PYRO The value of MR.

[0094] For example, when omitted Figure 5 When the current limiter 2000b and electronic switch 2002b are in use, the control circuit 202 can set the maximum current I of the current limiter (e.g., current limiter 2000) via the signal IMAX. MEAS The measurement cycle is started by asserting the signal DEP_CMD, where the value I... MEAS Preferably, it corresponds to a small measuring current. Conversely, when using current limiter 2000b and electronic switch 2002b, control circuit 202 can assert the signal MEAS_CMD and set the maximum current I for current limiter 2000a via signal IMAX (or directly via signal MEAS_CMD). MEAS .

[0095] For example, in various embodiments, the current I is selected in the range between 5 and 100 mA. MEAS For example, between 20 and 60 mA, such as approximately 40 mA. In various embodiments, the value I... MEAS It can be configurable, for example, programmable. For example, the programmable values ​​disclosed herein can be received via the communication interface of the control circuit 202 or stored in the non-volatile memory of the control circuit 202.

[0096] Next, in various embodiments, the control circuit 202 obtains signals MV and MI, and sets the value MR (indicating resistor R) as... PYRO The ratio MV / MI is calculated, i.e., MR = MV / MI. In various embodiments, instead of explicit measurement, it should be compared with the maximum value I. MEAS The corresponding current I PYRO The control circuit 202 can assume that the value MI is similar to a predetermined value (and the value I). MEASCorresponding to, that is, the control circuit 202 can assign the value MR (indicating resistor R) to the value of the resistor R. PYRO The ratio MV / MI is calculated as MR = MV / MI, where MI is a predetermined value. In various embodiments, the control circuit 202 may assume that the value MI is related to the predetermined value (and the value I). MEAS (Corresponding) Corresponding, and simply use the value MV for the value MR, that is, MR=MV.

[0097] Finally, in the considered embodiment, the control circuit 202 stops the measurement cycle, for example, by deasserting the signal DEP_CMD or MEAS_CMD.

[0098] Specifically, if the undeployed pyrotechnic device 101 is coupled between terminals 122a and 122b, then the resistance R between terminals 122a and 122b is... PYRO It should be within the expected range. Accordingly, in various embodiments, the control circuit 202 sets the value MR (indicator resistor R) at step 1004. PYRO The resistance is compared with a first and a second threshold, where the second threshold is greater than the first threshold. For example, a typical undeployed pyrotechnic device 101 should have a resistance value between 1 and 3 Ω. However, the connecting cable used to couple the pyrotechnic device 101 may also have additional resistance, for example, in the range between 0.1 and 1.1 Ω. Accordingly, in various embodiments, the first threshold may indicate the minimum resistance of a properly coupled undeployed pyrotechnic device 101, for example, a resistance of 1 Ω, and the second threshold may indicate the maximum resistance of a properly coupled undeployed pyrotechnic device 101, for example, a resistance of 3 Ω. In various embodiments, the first or second threshold may be settable, for example, programmable.

[0099] Accordingly, in various embodiments, in response to the determination that the value MR is less than a first threshold or greater than a second threshold (the output "N" of verification step 1004), the control circuit 202 proceeds to step 1016, where it signals an error, and the operation terminates at stop step 1020. For example, in various embodiments, the control circuit 202 sets a status signal to indicate an error in the pyrotechnic device 101.

[0100] In various embodiments, the control circuit 202 can also signal various types of errors. For example, in response to a determination value MR being less than a first threshold, the control circuit 202 can signal a first error type, such as indicating a short circuit error. Conversely, in response to a determination value MR being greater than a second threshold, the control circuit 202 can signal a second error type, such as indicating an open circuit error.

[0101] In various embodiments, the control circuit 202 may also determine the value MI (indicator current I) at step 1014. PYRODoes it have the expected value (compared to value I)? MEAS (Corresponding). For example, in this case, control circuit 202 may also proceed to error step 1016 in response to determining that the signal MI does not have the expected value. In various embodiments, control circuit 202 may be configured to determine the value I based on... MEAS For example, the expected value can be determined by the current value of IMAX. Alternatively, the expected value can be settable, for example, programmable.

[0102] Additionally or alternatively, in various embodiments, the control circuit 202 may also monitor, at step 1002, a first current flowing between terminals 121 and 122a via a first current sensor and a second current flowing between terminals 122b and 123 via a second current sensor. In this case, the control circuit 202 may also determine at step 1004 whether the first current corresponds (approximately) to the second current. For example, in this case, the control circuit 202 may also proceed to error step 1016 in response to determining that the first current does not (approximately) correspond to the second current (this, for example, indicates a leakage condition).

[0103] Additionally or alternatively, in various embodiments, the control circuit 202 may compare the voltage at terminal 122a or the voltage at terminal 122b with a corresponding expected value range. For example, in this way, the control circuit 202 may detect that terminal 122a or terminal 122b is coupled to a power supply voltage V. IN It's still the ground.

[0104] Therefore, in various embodiments, steps 1002 and 1004 are used to determine whether the undeployed pyrotechnic device 101 is correctly coupled to terminals 122a and 122b.

[0105] In various embodiments, the control circuit 202 is configured to periodically repeat steps 1002 and 1004. For example, in Figure 6 In response to the determination that the value MR is greater than the first threshold and less than the second threshold (verifying the output "Y" of step 1004), the control circuit 202 returns to step 1002. When also using the current I... PYRO During the additional verification operation, the control circuit 202 may return to step 1002 only if the value MI has the expected value or the first current (approximately) corresponds to the second current.

[0106] Figure 6Additional outputs of verification step 1004 are shown. Specifically, in various embodiments, control circuitry 202 verifies whether the ignition request signal REQ is asserted at this step. However, this verification can be implemented via additional verification steps, or it can be implemented asynchronously with respect to the periodic verifications at steps 1002 and 1004, for example, via an interrupt of the microprocessor of control circuitry 202 or via separate hardware circuitry. In various embodiments, the periodic verifications at steps 1002 and 1004 are repeated as long as the ignition request signal REQ remains deasserted.

[0107] Specifically, in response to the determination that the ignition request signal REQ is asserted (e.g., verifying the output "DEP" of step 1004), control circuit 202 proceeds to step 1006. Specifically, at step 1006, control circuit 202 begins a deployment cycle. For example, in various embodiments, control circuit 202 sets the maximum current I for the current limiter (e.g., current limiter 2000a) via the signal IMAX (or directly via the signal DEP_CMD). DEP It asserts the signal DEP_CMD to begin the deployment cycle, where the value I DEP Preferably, it corresponds to the maximum deployment current. For example, in various embodiments, the maximum current I is selected in the range between 1 and 4A. DEP For example, between 1 and 3.5A, such as approximately 1.2A, 1.5A, 1.75A, 2.0A, or 3.5A.

[0108] Next, the control circuit 202 monitors the value MI at step 1008 until it reaches a given time period t. DC And once the time period t DC Once completed, control circuit 202 stops the deployment cycle at step 1010, for example, by deasserting the signal DEP_CMD.

[0109] Specifically, such as Figure 7 As shown, once the signal DEP_CMD is asserted, the current I supplied to the pyrotechnic device 101 is... PYRO It should be increased to the maximum value I. DEP Furthermore, once the pyrotechnic device 101 reaches time t... DEPLOY Subsequent deployment, current I PYRO It decreases again because the resistance R PYRO It has been increased.

[0110] Therefore, in various embodiments, the control circuit 202 determines the current I. PYRO Greater than a given threshold I TH Time period t DEPLOY Is it longer than the time threshold t? TH In various embodiments, in order to determine the current I...DEP Whether to supply power to the pyrotechnic device 101 can be determined by the current I. DEP Choose a threshold I within the range of 70% to 95%. TH .

[0111] Accordingly, in various embodiments, the control circuit 202 periodically modulates the signal MI with a corresponding threshold MI. TH (Indicator threshold I) TH A comparison is made. In response to determining that the signal MI is greater than the threshold MI... TH The control circuit 202 increments the count value CNT. Conversely, in response to the determination signal MI being less than the threshold MI... TH The control circuit 202 prevents the increase of the count value CNT. Accordingly, in the considered embodiment, when the current I... PYRO With the maximum value I DEP The corresponding value of MI is selected within the range of 70% to 95% of the signal MI. TH In various embodiments, the control circuit 202 is configured to operate according to the value I. DEP (For example, the current value of IMAX) to determine the threshold MI TH Alternatively, the threshold MI TH It can be configurable, for example, programmable.

[0112] Figure 8 An alternative embodiment is shown, in which the comparison is performed directly in the current measurement circuit 206. Specifically, in the considered embodiment, transistors 2064 and 2068 are coupled between node A and terminal 123. Furthermore, current source 2070 is coupled to the supply voltage (e.g., voltage V). IN (or additional power supply voltage V) ANA Between node A and node A.

[0113] Specifically, in Figure 5 In the embodiment shown, the current I MON With current I PYRO Proportional, that is, I MON =I PYRO / N, where N corresponds to a ratio between transistors 2002a and 2064, for example, N=1000. Conversely, in Figure 8 In the embodiment shown, the current source 2070 is configured to provide I MON,TH =M⋅(I PYRO The maximum current of / N), where M represents the current I. DEP The percentage of the threshold, for example, choosing M in the range between 0.7 and 0.95.

[0114] Accordingly, in the considered embodiment, when the current absorbed by transistor 2068 is less than IMON,TH At that time, that is, because the current I PYRO Less than threshold I TH The voltage at node A is high. Conversely, when the current absorbed by transistor 2068 is greater than I... MON,TH At that time, that is, because the current I PYRO Greater than threshold I TH The voltage at node A is low. Accordingly, in this way, the voltage at node A directly indicates the current I. PYRO Greater than or less than threshold I TH The fact is that, for example, in various embodiments, the current measurement circuit 206 includes a logic inverter 2072 configured to generate a signal CI based on the voltage at node A. Accordingly, in this case, in response to the determination signal CI being asserted, the control circuit 202 can increment the count value CNT. Conversely, in response to the determination signal CI being deasserted, the control circuit 202 can prevent the increment of the count value CNT. In various embodiments, the current comparison operation can also be implemented using other types of analog comparison circuits.

[0115] Accordingly, the count value CNT indicates the current I within it. PYRO Greater than current I TH The control circuit 202 can be configured to respond to the time limit once the count value CNT exceeds the count threshold CNT. TH Regarding the assertion signal IDEP_OK, the count threshold CNT TH With the requested minimum time t TH Correspondingly. In various embodiments, verification of the count value CNT can be performed during the deployment cycle, for example, during step 1008, or after the deployment cycle, for example, at step 1010. In various embodiments, the time threshold t TH Or count threshold CNT TH It can be configurable, for example, programmable.

[0116] In various embodiments, the count value CNT can be provided by a digital counter or an analog ramp generator. Accordingly, the comparison of the count values ​​can also be implemented via digital or analog comparators, respectively.

[0117] Once the control circuit 202 has stopped the deployment cycle at step 1010, the control circuit 202 proceeds to step 1012, where the control circuit 202 again obtains the resistance R between the indicator terminals 122a and 122b. PYRO The value MR. For a description of this step, refer to step 1002. For example, as previously described, control circuit 202 can set the maximum current I of the current limiter (e.g., current limiter 2000) via the signal IMAX. MEASThe measurement cycle is initiated by an assertion signal MEAS_CMD (or alternatively, DEP_CMD). Next, the control circuit 202 obtains the values ​​MV and, optionally MI, and determines the corresponding value MR, for example, MR = MV / MI or MR = MV, where MV corresponds to the measured value and MI corresponds to the measured value or a predetermined value.

[0118] Finally, control circuit 202 stops the measurement cycle by deasserting the signal MEAS_CMD (or alternatively, the signal DEP_CMD). In various embodiments, the calculation of the value MR at steps 1002 and 1012 can also be performed once the measurement cycle has ended.

[0119] Specifically, if the deployed pyrotechnic device 101 is correctly coupled between terminals 122a and 122b, then the resistance R between terminals 122a and 122b is... PYRO It should be within the expected range. For example, a properly coupled deployed pyrotechnic device 101 can have a resistance R of at least 100Ω. PYRO .

[0120] Accordingly, in various embodiments, control circuitry 202 compares the value MR with a third threshold that indicates the minimum resistance (e.g., a resistance of 100 Ω) of the properly coupled deployed pyrotechnic device 101. In various embodiments, the third threshold may be settable, for example, programmable.

[0121] Accordingly, in various embodiments, the control circuit can verify at step 1014 whether:

[0122] - Deployment current I DEP Terminals 122a and 122b have been supplied with a minimum time t. TH For example, because the IDEP_OK signal is asserted, and

[0123] - at (time t) DC At the end of the deployment cycle, resistor R PYRO It has increased to above the third threshold, indicating the deployment of pyrotechnic devices.

[0124] Specifically, in response to determining the deployment current I DEP Minimum time t has been provided TH And the resistance R PYROOnce the threshold value has increased above the third threshold (verification step 1014 output "Y"), control circuit 202 can assume that pyrotechnic device 101 has been deployed and operation terminates at stop step 1020. In various embodiments, control circuit 202 can signal the correct deployment of pyrotechnic device 101 before proceeding to the stop step. For example, in various embodiments, control circuit 202 sets a status signal to indicate the correct deployment of the pyrotechnic device.

[0125] Conversely, if at least one of the verifications fails, i.e., in response to determining the deployment current I... DEP Minimum time t not provided TH or resistor R PYRO If the count does not increase above the third threshold, then control circuit 202 can perform different operations. For example, in the simplest case (verifying the output "N" in step 1014), control circuit 202 can return to step 1006 to start a new deployment cycle and eventually reset the count value CNT.

[0126] However, when the connection to the pyrotechnic device 101 is interrupted during the deployment cycle, thereby creating an open circuit between terminals 122a and 122b, the current I... PYRO Decrease and resistance R PYRO An increase indicates an error. Accordingly, in various embodiments, in response to determining the deployment current I... DEP Minimum time t not provided TH And the resistance R PYRO If the threshold has been exceeded, the control circuit 202 may proceed to error step 1016. For example, in this case, the control circuit 202 may generate an error signal that can be used to activate another deployment circuit of the same pyrotechnic device 101 or another pyrotechnic device. Additionally or alternatively, in various embodiments, the control circuit 202 sets a status signal to indicate an error during the deployment of the pyrotechnic device. For example, in this case, the control circuit 202 may set a status signal to indicate an open-circuit condition during the deployment of the pyrotechnic device.

[0127] Accordingly, in various embodiments, the control circuit 202 may (only) respond to determining the deployment current I DEP Minimum time t has been provided TH And the resistance R PYRO If the threshold is not increased above the third threshold, return to step 1006.

[0128] In various embodiments, similar to step 1004, control circuit 202 may perform additional verification operations. For example, in various embodiments, control circuit 202 verifies whether the value MR is greater than a first threshold indicating the minimum value of the undeployed pyrotechnic device 101. For example, in this case, in response to determining that the value MR is less than the first threshold, which may indicate a short circuit between terminals 122a and 122b, control circuit 202 may proceed to error step 1016. For example, in this case, control circuit 202 may set a status signal to indicate a short circuit condition during the deployment of the pyrotechnic device.

[0129] Additionally or alternatively, in various embodiments, the control circuit 202 may also monitor, at step 1012, a first current flowing between terminals 121 and 122a via a first current sensor, and a second current flowing between terminals 122b and 123 via a second current sensor. In this case, the control circuit 202 may also determine at step 1014 whether the first current corresponds (approximately) to the second current. For example, in this case, the control circuit 202 may also proceed to error step 1016 in response to determining that the first current does not (approximately) correspond to the second current, thereby detecting a possible leakage current at terminals 121 and 123. For example, in this case, the control circuit 202 may set a status signal to indicate a leakage error during the deployment of the pyrotechnic device.

[0130] Additionally or alternatively, in various embodiments, the control circuit 202 may compare the voltage at terminal 122a or the voltage at terminal 122b with a corresponding expected value range. For example, in this way, the control circuit 202 may detect that terminal 122a or terminal 122b is coupled to the supply voltage V. IN Alternatively, in this case, the control circuit 202 may also proceed to error step 1016 in response to determining that the voltage at terminal 122a or the voltage at terminal 122b is not within the corresponding expected value range.

[0131] Accordingly, in various embodiments, the value MR obtained at step 1002 should be between a first and a second threshold (e.g., between 1 and 3 Ω), while the value MR obtained at step 1012 should be greater than a third threshold (e.g., greater than 100 Ω). In various embodiments, when using ADC 2040, control circuitry 202 can therefore be configured to change the corresponding input range of the ADC. Similarly, when using ADC 2062 (or a similar current ADC), control circuitry 202 can change the corresponding input range of the ADC because the deployed current I... DEP It should be significantly greater than the measured current I. MEAS .

[0132] Therefore, the control circuit 202 disclosed herein can monitor time t DEPLOY (Step 1008) and the resistance R after the deployment cycle PYRO (1010) Reliably detect the correct deployment of the pyrotechnic device. Specifically, in various embodiments, when time t DEPLOY Greater than the time threshold t TH And the resistance R PYRO When the resistance is greater than the minimum resistance of the deployed pyrotechnic device, the control circuit 202 detects correct deployment at step 1014.

[0133] Furthermore, when step 1014 signals that the pyrotechnic device 101 may not have been deployed during the deployment cycle (step 1008), the control circuit 202 can implement an automatic retry mechanism. In various embodiments, the control circuit 202 can also be configured to monitor the number of retries. As previously described, the control circuit 200 can also implement additional controls to detect errors during the deployment cycle.

[0134] The aforementioned deployment circuit 20 can be used in various types of pyrotechnic devices, for example, within pyrotechnic fuses or pyrotechnic tubes. In fact, one or more of the parameters of the control circuit 202 (e.g., the first, second, and third threshold values ​​of MR, the measured current I) MEAS and deployment current I DEP The value of IMAX, the current threshold I TH or MI TH or time threshold t TH Or count threshold CNT TH It can be configurable for a particular pyrotechnic device 101, for example, programmable.

[0135] Furthermore, in high-end systems, once the given maximum number of retries has been performed (or an error condition is detected at verification step 1014), the control circuit 202 can assert the signal. For example, this signal can be used to drive redundant driver circuitry. Figure 5 In the middle, or redundantly deployed circuit 20.

[0136] Of course, without departing from the principles of the invention, the details of the construction and embodiments may be varied extensively with respect to what is described and illustrated herein purely as an example, without departing from the scope of the invention as defined by the appended claims.

[0137] While this description has been described in detail, it should be understood that various changes, substitutions, and alterations may be made without departing from the spirit and scope of this disclosure as defined by the appended claims. Identical elements are designated by the same reference numerals in the various figures. Furthermore, the scope of this disclosure is not intended to be limited to the specific embodiments described herein, as those skilled in the art will readily recognize from this disclosure that existing or later-developed processes, machines, manufactures, compositions of matter, components, methods, or steps can perform substantially the same functions or achieve substantially the same results as the corresponding embodiments described herein. Accordingly, the appended claims are intended to include such processes, machines, manufactures, compositions of matter, components, methods, or steps within their scope.

[0138] Accordingly, the specification and drawings should be regarded as merely an illustration of this disclosure as defined by the appended claims, and are intended to cover any and all modifications, alterations, combinations or equivalents falling within the scope of this disclosure.

Claims

1. A deployment circuit for a pyrotechnic device, the deployment circuit comprising: A pair of terminals, the pair of terminals being able to be coupled to the pyrotechnic device; A driver circuit configured to selectively energize the pyrotechnic device; as well as Control circuit, the control circuit being configured to: The driver circuit is driven according to the ignition request signal. The deployment cycle begins by asserting a deployment control signal in response to the assertion of the ignition request signal, wherein the deployment current flowing to the pyrotechnic device via the pair of terminals is limited to a first maximum value. Monitor the duration of time corresponding to the deployment current exceeding the current threshold. The deployment cycle is stopped after a predetermined time period by deasserting the deployment control signal. The first resistance value of the pyrotechnic device is determined via the pair of terminals, and A successful deployment signal is generated in response to the time duration being greater than a time threshold and the first resistance value being greater than a first resistance threshold.

2. The deployment circuit according to claim 1, wherein, The deployment circuit includes a positive terminal and a negative terminal, wherein the driver circuit includes: An electronic switch configured to selectively couple the positive terminal to a first terminal of the pair of terminals and the negative terminal to a second terminal of the pair of terminals in response to an assertion of the deployment control signal; and A current limiter configured to limit the current supplied via the first terminal and the second terminal to the first maximum value.

3. The deployment circuit according to claim 1, wherein, In response to the ignition request signal being de-asserted, the control circuit is configured to: The second resistance value of the pyrotechnic device is determined via the pair of terminals; Determine whether the second resistance value is between a second resistance threshold and a third resistance threshold that is greater than the second threshold, wherein the first resistance threshold is greater than the third resistance threshold; as well as An error signal is generated in response to the second resistance value not being between the second resistance threshold and the third resistance threshold.

4. The deployment circuit according to claim 3, wherein, The control circuit is configured to initiate a second deployment cycle in response to the time duration being greater than the time threshold and the first resistance value being greater than the second resistance threshold but less than the first resistance threshold.

5. The deployment circuit according to claim 3, wherein, The control circuit is configured to generate a second error signal in response to the time duration being greater than the time threshold and the first resistance value being less than the second resistance threshold.

6. The deployment circuit according to claim 3, wherein, The control circuit is configured to generate a third error signal in response to the time duration being less than or equal to the time threshold and the first resistance value being greater than the first threshold.

7. The deployment circuit according to claim 1, wherein, The control circuit is configured to initiate a second deployment cycle in response to the time duration being greater than the time threshold and the first resistance value being less than the first resistance threshold.

8. A deployment circuit for a pyrotechnic device, the deployment circuit comprising: A pair of terminals, the pair of terminals being able to be coupled to the pyrotechnic device; Positive and negative terminals, which are configured to receive a power supply voltage; A driver circuit configured to selectively energize the pyrotechnic device, the driver circuit comprising: A first current limiter, coupled between the positive terminal and a first terminal of the pair of terminals, is configured to limit the current flowing to the pyrotechnic device via the pair of terminals to a first maximum value. A second current limiter is configured to limit the current flowing to the pyrotechnic device via the pair of terminals to a second maximum value, which is less than the first maximum value. A first electronic switch, configured to selectively couple a second current limiter between a second terminal and a negative terminal of the pair of terminals according to a measurement control signal, and A second electronic switch, configured to selectively couple a second terminal of the pair of terminals to the negative terminal according to a deployment control signal; and Control circuit, the control circuit being configured to: The driver circuit is driven according to the ignition request signal. The resistance value of the pyrotechnic device is determined via the pair of terminals using the following operation: Configure the first current limiter to limit the current to the second maximum value. Assert the measurement control signal, and Obtain the voltage value indicating the voltage at the pair of terminals. The resistance value corresponds to the voltage value, the voltage value divided by a predetermined current value, or the voltage value divided by a measured current value indicating the current supplied through the pair of terminals.

9. The deployment circuit of claim 8 further includes a current measurement circuit configured to obtain a value indicating the current flowing through the second electronic switch.

10. The deployment circuit according to claim 9, wherein, The second electronic switch includes a first n-channel field-effect transistor (FET), and the current measurement circuit includes: A second n-channel FET, the second n-channel FET having a gate terminal coupled to the gate terminal of a first n-channel FET; and A regulator circuit is configured to vary the current flowing through the second n-channel FET until the drain-source voltage of the second n-channel FET corresponds to the drain-source voltage of the first n-channel FET. The current measurement circuit is configured to obtain a value indicating the current flowing through the second electronic switch by monitoring the current flowing through the second n-channel FET.

11. The deployment circuit according to claim 8, wherein, The control circuit is configured as follows: The deployment cycle is initiated by asserting the deployment control signal in response to the assertion of the ignition request signal, wherein the deployment current flowing to the pyrotechnic device via the pair of terminals is limited to the first maximum value. By incrementing a count value in response to the deployment current exceeding a current threshold during the deployment cycle, the duration of time corresponding to the deployment current exceeding the current threshold is monitored. The deployment cycle is stopped after a predetermined time period by deasserting the deployment control signal. After the deployment cycle is stopped, the post-deployment resistance value of the pyrotechnic device is determined via the pair of terminals. Determine whether the count value is greater than a counting threshold, the counting threshold corresponding to the minimum time duration; as well as A successful deployment signal is generated in response to the count value being greater than the count threshold and the post-deployment resistance value being greater than the deployment resistance threshold.

12. The deployment circuit of claim 11, further comprising a current measuring circuit configured to obtain a value indicating the current flowing through the second electronic switch, the current measuring circuit comprising: A current source configured to provide a threshold current corresponding to the current threshold; as well as A comparison circuit configured to generate a comparison signal indicating whether the deployment current exceeds the current threshold. The control circuit is configured to increment the count value in response to the comparison signal.

13. The deployment circuit according to claim 8, wherein, The control circuit is configured to periodically: when the ignition request signal is de-asserted. The resistance value of the pyrotechnic device is determined via the pair of terminals; Determine whether the resistance value is between the third resistance threshold and the fourth resistance threshold; and An error signal is generated in response to the resistance value not being between the third resistance threshold and the fourth resistance threshold.

14. The deployment circuit according to claim 13, wherein, The third resistance threshold corresponds to the minimum resistance value of a correctly coupled, undeployed pyrotechnic device, and the fourth resistance threshold corresponds to the maximum resistance value of a correctly coupled, undeployed pyrotechnic device.

15. A method of operating a deployment circuit for a pyrotechnic device, the method comprising: Couple a pair of terminals of the deployment circuit to the pyrotechnic device; Drive the driver circuit according to the ignition request signal; The deployment cycle is initiated by asserting a deployment control signal in response to the assertion of the ignition request signal, wherein the deployment current flowing to the pyrotechnic device via the pair of terminals is limited to a first maximum value. Monitor the duration of time corresponding to when the deployed current exceeds the current threshold; The deployment cycle is stopped after a predetermined time period by deasserting the deployment control signal. A first resistance value of the pyrotechnic device is determined via the pair of terminals; as well as A successful deployment signal is generated in response to the time duration being greater than a time threshold and the first resistance value being greater than a first resistance threshold.

16. The method of claim 15, wherein, The driver circuit includes an electronic switch and a current limiter, and the method further includes: In response to the assertion of the deployment control signal, the positive terminal is selectively coupled to the first terminal of the pair of terminals and the negative terminal is coupled to the second terminal of the pair of terminals via the electronic switch; and The current supplied via the first terminal and the second terminal is limited to the first maximum value by the current limiter.

17. The method of claim 15, further comprising, in response to the ignition request signal being de-asserted: The second resistance value of the pyrotechnic device is determined via the pair of terminals; Determine whether the second resistance value is between a second resistance threshold and a third resistance threshold greater than the second threshold, wherein the first resistance threshold is greater than the third resistance threshold; and An error signal is generated in response to the second resistance value not being between the second resistance threshold and the third resistance threshold.

18. The method of claim 17, further comprising initiating a second deployment cycle in response to the time duration being greater than the time threshold and the first resistance value being greater than the second resistance threshold but less than the first resistance threshold.

19. The method of claim 17, further comprising generating a second error signal in response to the time duration being greater than the time threshold and the first resistance value being less than the second resistance threshold.

20. The method of claim 17, further comprising generating a third error signal in response to the time duration being less than or equal to the time threshold and the first resistance value being greater than the first threshold.

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