Device and method for providing an activation voltage for a safety device for a vehicle and safety device

Abstract

Device (102) for providing an activation voltage (VH), in particular a limited, switchable (high / low-impedant) ignition high-side supply voltage, for a safety device (104) for a vehicle (100), wherein the device (102) has the following features: a supply connection (110; 220, 224, 228, 230) for applying a first supply voltage potential, an activation connection (112) in the form of an output for outputting the activation voltage (VH), a control connection (114) for reading a control signal (P_SVR) and a ground connection (115) for a second supply potential; a through-switch (T_p) with a control input, wherein the through-switch (T_p) is connected between the supply terminal (110; 220, 224, 228, 230) and the activation terminal (112), and is configured to provide a conductive, in particular low-resistance, connection between the supply terminal (110; 220, 224, 228) and the activation terminal (112) when a first signal level is applied to the control input, and to block the conductive connection between the supply terminal (110; 220, 224, 228, 230) and the activation terminal (112) when a second signal level is applied to the control input. a first control switch (T_D1) with a first terminal, a second terminal and a control input, wherein the first terminal is connected to the control input of the through switch (T_p), the second terminal to the activation terminal (112) and the control input is connected to the control input of the through switch (T_p) via a first resistor (Rc); a second control switch (T_D2) with a first terminal, a second terminal and a control input, wherein the first terminal is connected via at least a second resistor (Rb2, Rb2_1) to the control input of the first control switch (T_D1), the second terminal to a second supply voltage potential (115) and the control input via at least a third resistor (Rp1, Rp2, Rp3, Rp4) to the supply terminal (110; 220, 224, 228) and via a diode (ZD2) to the second supply voltage potential (115); and a third control switch (T_D3) with a first terminal, a second terminal and a control input, wherein the first terminal is connected to the control input of the second control switch (T_D2), the second terminal to the second supply voltage potential (115) and the control input to the control terminal (114).

Description

State of the art

[0001] The invention is based on a device or a method according to the preamble of the independent claims.

[0002] Airbags in vehicles can be triggered using safety semiconductors.

[0003] From DE 10 2004 010 135 B4, a device for supplying power to at least one ignition output stage by means of an ignition current from an energy reserve for an airbag is known. In this device, a voltage regulator between the energy reserve and the ignition output stage is controlled both as a voltage regulator and as a safety semiconductor.

[0004] From DE 60 2004 006 973 T2 a driver arrangement is known in which control means are provided for controlling the supply voltage during the activation of a vehicle safety activation element.

[0005] Another control device with an ignition pill for activating an occupant protection device is known from DE 101 47 884 A1. Disclosure of the invention

[0006] Against this background, the approach presented here introduces a device and a method for providing an activation voltage for a safety device for a vehicle and a safety device according to the main claim and the dependent claims. According to the main claim, a device for providing an activation voltage, in particular a limited, switchable (high / low impedant) ignition high-side supply voltage, for a safety device for a vehicle is claimed, wherein the device has the following features: a supply connection for applying a first supply voltage potential, an activation connection in the form of an output for outputting the activation voltage, a control connection for reading a control signal and a ground connection for a second supply potential; a through-switch with a control input, wherein the through-switch is connected between the supply terminal and the activation terminal, and is configured to provide a conductive, in particular low-resistance, connection between the supply terminal and the activation terminal when a first signal level is applied to the control input, and to block the conductive connection between the supply terminal and the activation terminal when a second signal level is applied to the control input. a first control switch with a first terminal, a second terminal and a control input, wherein the first terminal is connected to the control input of the through switch, the second terminal to the activation terminal and the control input is connected to the control input of the through switch via a first resistor; a second control switch with a first terminal, a second terminal and a control input, wherein the first terminal is connected via at least a second resistor to the control input of the first control switch, the second terminal to a second supply voltage potential and the control input via at least a third resistor to the supply terminal and via a diode to the second supply voltage potential; and a third control switch with a first terminal, a second terminal and a control input, wherein the first terminal is connected to the control input of the second control switch, the second terminal is connected to the second supply voltage potential and the control input is connected to the control terminal.

[0007] The measures listed in the dependent claims enable advantageous further developments and improvements of the device specified in the independent claim.

[0008] By appropriately designing a device, for example a safety semiconductor, to provide an activation voltage, for example to activate an airbag, the power consumption of the device can be kept very low.

[0009] A suitable device for providing an activation voltage, in particular a limited, switchable (high / low-impedant) ignition high-side supply voltage, for a safety device for a vehicle has the following features: a supply connection for the initial setup supply voltage potential, an activation connection in the form of an output for outputting the activation voltage, a control connection for reading a control signal and a ground connection for a second supply potential, also called second supply voltage potential or ground; a through-switch with a control input, wherein the through-switch is connected between the supply terminal and the activation terminal, and is configured to provide a conductive connection between the supply terminal(s) and the activation terminal when a first signal level is applied to the control input, and to block the conductive connection between the supply terminal(s) and the activation terminal when a second signal level is applied to the control input; a first control switch with a first terminal, a second terminal and a control input, wherein the first terminal is connected to the control input of the through switch, the second terminal to the activation terminal and the control input is connected to the control input of the through switch via a first resistor; a second control switch with a first terminal, a second terminal and a control input, wherein the first terminal is connected via at least a second resistor to the control input of the first control switch, the second terminal to a second supply voltage potential and the control input via at least a third resistor to the supply terminal and via a diode to the second supply voltage potential; and a third control switch with a first terminal, a second terminal and a control input, wherein the first terminal is connected to the control input of the second control switch, the second terminal is connected to the second supply voltage potential and the control input is connected to the control terminal.

[0010] The device can be implemented as a safety semiconductor that can be connected between the vehicle's power supply and the safety device. The first supply voltage potential can be a supply voltage, and the second supply voltage potential can be a ground potential. The device can be configured to provide the activation voltage when a suitable control signal is present at the control terminal. The use of control switches reduces the device's power consumption and ensures a reliable supply of the activation voltage. Furthermore, false tripping caused by an unintended supply of the activation voltage can be avoided.If two circuit elements are "connected," this can mean that they are directly connected via a through-line or via at least one other element, such as a resistor. According to one embodiment, a through-switch can be understood as a limiter.

[0011] The second control switch can be configured so that it is open when the third control switch is closed in response to the control signal received from the control terminal. Opening the second control switch closes the through-switch / limiter, thus providing the low-impedance limited activation voltage.

[0012] The device can have two secondary resistors connected in parallel. This ensures reliable operation of the device even if one of the two secondary resistors fails.

[0013] Furthermore, the device can have a series circuit consisting of a first parallel-connected resistor pair and a second parallel-connected resistor pair. This achieves redundancy, thereby increasing the reliability of the device.

[0014] The device can include a limiting switch (impedance converter, output transistor of a Zener voltage, ZD1) with a first terminal, a second terminal, and a control input. The first terminal can be connected to the supply terminal, the second terminal to the control input of the switching switch via series resistors Rg1 and Rg2, and the control input to the supply terminal via at least a fourth resistor and to the second supply voltage potential via a precision Zener diode. A suitable signal level can be applied to the control input of the switching switch via the limiting switch.

[0015] The switches can be implemented as transistors. This is a cost-effective and reliable implementation. The through-switch can be a power MOSFET. The first control switch can be a bipolar transistor. The second control switch can be an NMOS transistor.

[0016] The device can be designed in such a way that it is suitable for sleep airbag control units, i.e., even with a permanent supply at the terminals of the supply connection up to 16.5V, no current (<2µA @ 40°C) is drawn unless a collision occurs.

[0017] A safety device for a vehicle has the following features: a device for providing an activation voltage for a safety device for a vehicle; at least one vehicle battery which is switched or permanently connected to the supply terminal and the ground terminal of the device in order to provide a battery voltage as the first supply voltage potential against the ground terminal at the supply terminal; an energy reserve device connected to the device's supply terminal to provide a reserve voltage as the initial supply voltage potential to the supply terminal; and a safety device that is connected to the activation terminal of the device in order to be supplied by the activation voltage (high impedance and voltage-limited in the normal case or low impedance and voltage-limited in the case of a collision).

[0018] Therefore, the aforementioned device can be used as a safety semiconductor.

[0019] The safety device may optionally include at least one vehicle battery, which is connected as a permanent supply to the supply terminal, as well as as a switched supply to the supply terminal and the reference point (ground terminal) of the device, in order to provide a battery voltage as the first supply voltage potential against the ground terminal at the supply terminal.

[0020] The safety device in question can be a personal protective device, for example an airbag or a seatbelt tensioner.

[0021] A method for providing an activation voltage for a safety device for a vehicle using said activation voltage provision device comprises the following steps: Applying an initial supply voltage potential to the device's supply terminal; and Providing the control signal to the control port of the device.

[0022] This process can be implemented, for example, in software or hardware, or in a hybrid form of software and hardware, for example in a control unit.

[0023] In this context, a device can be understood as an electrical device that processes sensor signals and outputs control and / or data signals accordingly. The device may have an interface, which can be implemented in hardware and / or software. In the case of a hardware-based interface, the interfaces can, for example, be part of a so-called system ASIC, which incorporates various functions of the device. However, it is also possible that the interfaces are separate integrated circuits or consist at least partially of discrete components. In the case of a software-based interface, the interfaces can be software modules, which, for example, are located on a microcontroller alongside other software modules.

[0024] Examples of the approach presented here are shown in the drawings and explained in more detail in the following description. It shows: Fig. 1 a schematic representation of a vehicle with a device for providing an activation voltage for a safety device according to an exemplary embodiment; Fig. 2 a flowchart of a procedure according to an exemplary embodiment; and Fig. 3 a circuit diagram of a device for providing an activation voltage according to an exemplary embodiment.

[0025] In the following description of favorable embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the various figures and acting similarly, without repeating these elements.

[0026] Fig. Figure 1 shows a schematic representation of a vehicle 100 with a device 102 for providing an activation voltage for a safety device 104 according to an exemplary embodiment.

[0027] The safety device 104 includes, for example, a circuit “FLIC / S-ASIC” and an ignition device with which, for example, an airbag can be triggered, which can also be part of the safety device 104.

[0028] According to this embodiment, the device 102 is designed as a safety semiconductor device (SH) and has a supply terminal 110 for applying one or more first supply voltage potentials, an activation terminal 112 for outputting the activation voltage, and a control terminal 114 for reading a control signal. Furthermore, the device 102 includes a terminal for a second supply voltage potential, here a ground terminal 115, also called a reference point or ground reference point.

[0029] The supply terminal 110 comprises, for example, three contacts through which the device is supplied with three different reverse-polarity protected voltage potentials in the form of a battery voltage KL30 (permanent), a battery voltage KL15 / KL15R (switchable), and an energy reserve voltage VER < 40V (in active operation) from the energy reserve unit 116 for activation purposes. To provide the voltage limit of the activation voltage VH, the non-reverse-polarity protected energy reserve voltage VER of the energy reserve unit 116 is used via an exemplary fourth contact (230) in the supply terminal (110).

[0030] The control signal, also known as P_SH or P_SVR, can be read via control terminal 114. Device 102 is configured to switch the activation voltage, also known as VH, depending on the signal state of the control signal, into a low-impedance, voltage-limited state with respect to the supply voltages (220, 224, 228), into a blocking state with respect to the supply voltages (220, 224, 228), and into a high-impedance, voltage-limited state with respect to the supply voltage VER (230). Furthermore, device 102 is configured to limit the voltage VH.

[0031] According to one embodiment, the function of device 102 is such that it blocks (high impedance ≈ 1.21 kΩ and limits the voltage). In the "blocked" state (= T_P blocked) of device 102, the activation voltage VH = VH_HZ ≈ VH_lim * (Rb2_1 II Rb2) / (Rb2_1 II Rb2 + Rg1 + Rg2) + 0.1 V, provided IVH = 0 when the control signal is in the high Z or low state, and conducts (low impedance ≈ 5 Ω...50 mΩ and limits the voltage) when the control signal is in the high state. In the conducting state of device 102, the activation voltage VH = VH_LZ <= VH_lim - VH_th.

[0032] According to one embodiment, the device 102 is a safety semiconductor for ignition from a battery and an energy reserve 116 without current consumption in the so-called sleep state.

[0033] Device 102 is described below using an airbag system as an example, which can be connected to a permanent power supply (KL30). The system is started up or put into sleep mode via bus communication, for example CAN / FlexRay communication, and / or a wake-up line.

[0034] The requirement is to maintain a low system supply current in sleep mode. Device 102, in the form of a safety semiconductor, is shown as an example of an independent component connected in series with the ignition circuit's high- and low-side output stages. Device 102 can disconnect both battery leads connected to the supply terminal 110 and an energy reserve lead to the energy reserve unit 116, and in the event of a collision, selectively release the energy supply from the energy reserve unit 116 and / or the battery.

[0035] In addition, the output voltage provided at the activation terminal 112 is regulated and / or limited in order to optimally distribute the power loss during ignition to the ignition circuit components.

[0036] Advantageously, the device 102 can use the continuous supply (KL30) without exceeding the limits for the system supply current in sleep mode (= Sleep-Current).

[0037] For example, the supply current of the device 102 can be less than 2µA, ensuring robustness against moisture or the safe blocking and / or releasing of the energy supply from KL30 or energy reserve 116.

[0038] Device 102 makes it possible to meet the requirements for airbag systems with a sleep function in further supply scenarios. In particular, it enables the sleep current of <=100µA for the entire system to be maintained, even if the KL30 (permanent positive) and not exclusively the KL15 (ignition) are used as the input signal for device 102.

[0039] Furthermore, the system offers high robustness against leaks, such as moisture, without increasing power consumption during sleep mode. Similarly, measures can be implemented to further minimize the impact of assembly errors in production, eliminating the need for additional testing. This can be achieved through the targeted use of redundancy and diversity.

[0040] A through-switch in the form of a power MOSFET transistor can be used as an essential part of the design of device 102. The voltage supplies intended for ignition, here voltages KL15, KL30, and the voltage of the energy reserve 116, are supplied to device 102 with reverse polarity protection. Device 102 is enabled or disabled by means of a driver stage. The blocking will take effect when a relevant input voltage is present at device 102, even before the internal supply voltages can be established during the start of the airbag system.

[0041] According to one embodiment, the device 102 can be reliably controlled via a standard I / O port of a microprocessor with I / O voltages of 5V or 3.3V. In the RESET state, the device 102 will also reliably lock.

[0042] If the device 102 is implemented as a Power N-MOS transistor, the output voltage in the event of activation (crash) can be limited by suitable gate voltage specification, thus distributing the power loss between the device and the airbag high-side output stage.

[0043] Fig. Figure 2 shows a flowchart of a procedure for providing an activation voltage for a safety device in a vehicle. A device such as the one shown in the following can be used for this purpose: Fig. 1 and Fig. As described in section 3. In step 201, a first supply voltage potential is applied to the supply terminal of the device. In step 203, a control signal is provided to the control terminal of the device. The control signal activates the device so that it provides the activation voltage using the first supply voltage potential.

[0044] Fig. Figure 3 shows a circuit diagram of a device 102 for providing an activation voltage VH according to an exemplary embodiment. This can be an exemplary embodiment based on Fig. The device described in section 1 is involved.

[0045] A first contact 220 of the first supply terminal 110 of the device 102 is connected via a diode to a first vehicle battery 222 to provide a voltage KL30. A second contact 224 of the first supply terminal 110 is connected via a diode to a second vehicle battery 226 to provide a switched voltage KL15.

[0046] Typically, this involves only one vehicle battery with generator buffering. This battery is permanently connected to terminal 220 of supply terminal block 110 via a reverse polarity protection diode. The same vehicle voltage (vehicle battery with generator buffering) is also connected via a switched circuit, likewise via reverse polarity protection (diode), to the second terminal 224 of supply terminal block 110. The switch is closed either when the ignition is on (labeled KL15) or when the radio / accessory is on (labeled KL15R).

[0047] A third contact 228 of the first supply terminal 110 is connected via a reverse polarity protection diode to an energy reserve device 116 to provide a reverse polarity protected energy reserve voltage. A fourth contact 230 of the first supply terminal 110 is also connected to the energy reserve device 116 without reverse polarity protection.

[0048] The device 102, designed as a safety semiconductor SH, includes a device 240 for providing a stabilized VH limiting voltage VH_lim, which is connected on the input side to the fourth contact 230.

[0049] Furthermore, the device 102 has a through switch T_p, a first control switch T_D1, a second control switch T_D2 and a third control switch T_D3.

[0050] The through-switch T_p is connected between contacts 220, 224, 228 of the supply terminal 110 and the activation terminal 112. The through-switch T_p has a control input. When a first signal level is present at the control input, the through-switch T_p is closed, and when a second signal level is present at the control input, the through-switch T_p is open.

[0051] The first terminal of the first control switch T_D1 is connected to the control input of the through switch T_p, and the second terminal of the through switch T_p is connected to the activation terminal 112. The control input of the first control switch T_D1 is connected to the control input of the through switch T_p via a resistor Rc.

[0052] For example, the first terminal of the second control switch T_D2 is connected to the control input of the first control switch T_D1 via two resistors Rb2 and Rb2_1, and the second terminal of the second control switch T_D2 is connected to ground 115. The control input of the second control switch T_D2 is connected to contacts 220, 224, and 228 of supply terminal 110 via four resistors Rp1, Rp2, Rp3, and Rp4. Resistors Rp1 and Rp3 are connected in parallel, as are resistors Rp2 and Rp4. The first terminals of resistors Rp1 and Rp3 are connected to contacts 220, 224, and 228, the second terminals of resistors Rp1 and Rp3 are connected to the first terminals of resistors Rp2 and Rp4, and the second terminals of resistors Rp2 and Rp4 are connected to the control input of the second control switch T_D2. The control input of the second control switch T_D2 is further connected to ground 115 via a diode ZD2.

[0053] The first terminal of the third control switch T_D3 is connected to the control input of the second control switch T_D2, and the second terminal of the third control switch T_D3 is connected to ground 115. The control input of the third control switch T_D3 is connected to control terminal 114. For illustrative purposes, a resistor Rb is connected between control terminal 114 and the control input of the third control switch T_D3. Additionally, control terminal 114 is connected to ground 115 via a resistor Rbe1.

[0054] The activation terminal 112 is connected to ground 115 via capacitors Cout, Cout_1 and a diode Dout.

[0055] Device 240 includes a limiting switch (impedance converter) T_kop. A first terminal (collector, drain) of the limiting switch T_kop is connected to the beginning of the series circuit of resistors Rv1 and Rv2, and additionally to contact 230 of the supply terminal 110. A second terminal (emitter, source) of the limiting switch T_kop is connected via a diode D1 to an output of device 240, at which device 240 provides the voltage VH_lim. A control input (base, gate) of the limiting switch (base) T_kop is connected to the cathode of Zener diode ZD1, which is also connected to one end of the series circuit consisting of Rv1 and Rv2. By selecting the appropriate Zener voltage for diode ZD1, the voltage VH_lim can be adjusted to be optimally suited for the safety device 104. The anode of Zener diode ZD1 is connected to ground 115.

[0056] As an example, the output of device 240, which provides the voltage VH_lim, is connected to the control input (gate) of the through-switch T_p via a series circuit of two resistors RG1, RG2. The control input of the through-switch T_p is also connected to ground 115 via two capacitors Cg1, Cg2 connected in parallel.

[0057] In an airbag application, a reverse polarity protected high-current connection to the energy reserve voltage VER of the energy reserve capacity C_ER is provided, which is brought to the voltage suitable for the operating phases by a charging / discharging device 116.

[0058] Depending on the application requirements, additional high-current connections to vehicle voltages KL15 and KL30 are provided. The high-current inputs are connected in device 102 via a "wired OR" to the input voltage SH_IN of device 102, also referred to as the first supply potential. This wired OR connection ensures that, in the event of ignition, the energy reserve voltage VER, if present, is supported by the battery voltages KL15 and KL30. This allows ignition circuit activation even with insufficient energy reserve or in the event of an ER capacitor failure.

[0059] The non-reverse-polarity protected energy reserve voltage VER is used as the drive voltage for device 102. This serves a safety purpose by ensuring that, at the moment the vehicle voltage KL15 is switched on as the input voltage for device 102, there is no drive voltage yet present for the power MOSFET T_p of device 102. This drive voltage is only established after complete verification, for example by a system controller, through the slow build-up of the energy reserve voltage VER by means of the microcontroller-controlled charger / discharger for the energy reserve device 116. The same applies when, in sleep systems, the vehicle voltage KL30 remains as the input voltage for device 102 in parked vehicles.In this case, after the expiry of the autarky period and a subsequent active discharge by the discharge device 116 with final passive discharge of the energy reserve in an airbag system, there is no longer a control voltage for the power MOS transistor T_p of the device 102.

[0060] For controlling device 102, an input in the form of control input 114 is provided, which can be connected, for example, to an I / O port of the airbag microcontroller. Control can be achieved via 3.3V I / O or 5V I / O. This control serves to actively disable device 102 or to activate, a so-called conducting control, the power MOSFET transistor T_p for testing purposes or in the event of a collision.

[0061] According to the in Fig. In the embodiment shown in Figure 3, the power MOS transistor T_p, also referred to as T_power_nmos, is controlled by the bipolar transistor T_D1. If an airbag control unit is in sleep mode, in the worst case, the voltage KL30 may be present at the input of device 102, protected against reverse polarity. Otherwise, no other voltages are present, as the vehicle is unused. In such a case, the energy reserve is depleted within a few hundred milliseconds after the vehicle is switched off (due to energy consumption for the system's self-sufficiency period and further active and passive discharge (device 116)).

[0062] In this sleep mode, high demands are placed on the power consumption of the KL30-powered control units, in this case, device 102. To meet these requirements, an additional signal transistor, T_D2, is integrated into the circuit of device 102 as an NMOS transistor. This transistor, T_D2, has the lowest possible gate threshold voltage so that even the smallest available KL30 voltage can be used to ensure reliable shutdown of the power MOSFET output stage, T_p.

[0063] Transistor T_D2 is driven via redundant resistors Rp1, Rp2, Rp3, and Rp4. This four-resistor configuration ensures that even if one resistor fails (e.g., due to an open circuit or short circuit), no impermissible condition can occur. Furthermore, the resistors Rp1, Rp2, Rp3, and Rp4 can be dimensioned according to very robust design rules (e.g., less than 100 kΩ and moisture resistance) without violating the sleep current requirements of modern safety semiconductor circuits.

[0064] To ensure that impermissible voltages do not damage transistor T_D2 during jump-start conditions, a gate clamp diode ZD2 with, for example, an 18V clamp voltage is provided. This is necessary because standard signal MOSFETs must not be subjected to gate voltages exceeding 20V. A corresponding clamp structure is usually integrated into the MOSFET, but should also be provided externally as a redundant component, in this case, diode ZD2. In sleep mode, this has no effect on the sleep current of device 102, since the vehicle voltage (KL30) is supplied by the vehicle battery 222, not by the alternator, when the vehicle is parked (no operation). This voltage is typically not higher than 13.8V in the case of a lead-acid battery, meaning no clamp current is drawn into diode ZD2.

[0065] In operational mode (airbag in operation), with an energy reserve voltage of 33V and an effective pull-up resistor Rp1 II Rp3=42.85k and Rp2 II Rp4 = 43.25k = total 86.1k with passive or active locking by P_SVR=high Z / low, a static current draw of IRp<=[33V(VER)-18V (ZD2) / / 86.1k=0.174mA from the energy reserve 116 can be expected.

[0066] The transistor T_D2, which is driven by the pull-up resistors Rp1, Rp2, Rp3, Rp4, enables an emitter-base current in the PNP bipolar gate-source transistor T_D1 via the resistors Rb2, Rb2_1.

[0067] The transistor T_D1, via the conductive emitter-collector path, ensures that the power NMOS transistor T_p is switched off.

[0068] Two base resistors Rb2, Rb2_1 are used to ensure that, in the event of an interruption of one resistor Rb2, Rb2_1, transistor T_D1 can still be reliably driven and the Power_NMOS transistor T_p can still be actively locked.

[0069] Resistors Rb2 and Rb2_1 can also be made differently to allow them to be assembled from two different tapes during manufacturing. This increases robustness against manufacturing errors (incorrect tape, etc.) without having a safety-relevant or systematic impact. This method has been applied in this safety-critical circuit wherever necessary (Rp1 ≠ RP3 ≠ RP2 ≠ RP4; Rg1 ≠ Rg2; Rv1 ≠ Rv2; Rb2 ≠ Rb2_1).

[0070] In the event of a collision or test of the device 102, the resistor Rc ensures rapid control by clearing the emitter-base path of transistor T_D1.

[0071] The voltage VER supplied directly to device 102 from the energy reserve device 116 is clamped to a desired limiting value via resistors Rv1, Rv2 and the Zener diode ZD1. For example, to 27V. This voltage is then supplied to device 102 via the output coupling transistor Tkop and diode D1 as a limiting reference for the output voltage provided at the activation terminal 112 in the event of a collision or during testing, with no feedback effect, or at least essentially no feedback effect, and with reverse polarity protection. By appropriately selecting the clamping voltage of the Zener diode ZD1, any desired voltage VH_lim can be achieved during activation.

[0072] A high-level control signal P_SVR, read at control pin 114, activates the bipolar transistor T_D3 and switches off the NMOS_FET T_D2 as well as the PNP transistor T_D1. This allows the limited voltage VH_lim to be available to the power_NMOS T_p via resistors Rg1 and Rg2.

[0073] Resistors Rg1 and Rg2 serve to limit the current of the voltage VH_lim in the blocked state of device 102 in the event of a short circuit at device 102 to ground 115 or in the subsequent circuit 104. Redundancy ensures this function even in the event of a short circuit in either resistor Rg1 or Rg2.

[0074] Capacitances Cg1 and Cg2 prevent gate voltage fluctuations in the event of fluctuations in the voltage VER of the energy reserve 116, for example caused by high dynamic current draws during ignition circuit activation.

[0075] At the activation terminal 112, which serves as the output of device 102, a current-limited voltage is present when the device is off. This voltage is formed by the voltage VH_lim and the voltage divider ratio [Rb2*Rb2_1 / Rb2+Rb2_1] / {[Rb2*Rb2_1 / Rb2+Rb2_1]+Rg1+rg2} of the resistors Rg1, Rg2, Rb2, Rb2_1. This can be verified for testing purposes by measuring the voltage VH, for example, in a connected system ASIC / FLIC. When device 102 is activated, for example, in the event of a collision, the activation voltage VH < VH_lim-VGth(IVH) is present at the activation terminal 112. This can also be verified for testing purposes by measuring the voltage VH.

[0076] The output capacitances Cout and Cout_1 at the activation terminal 112 serve, firstly, for energy-limited high-current testing, for example, of downstream FLIC high-side power amplifiers, and secondly, for suppressing transients coupled into the voltage VH. The diode Dout serves to freewheel inductive current spikes, such as layout inductances. In one embodiment, the diode Dout is implemented as a Schottky diode.

[0077] The device 102 is characterized by very low leakage currents in sleep mode. Furthermore, according to one embodiment, attention is paid to the use of specific diverse and redundant components, such as resistors, to increase the reliability and fault tolerance of the device 102.

[0078] According to one embodiment, the device 102 is designed such that the device 102 is suitable for sleep airbag control units, i.e., even with a permanent supply to terminals 220, 224 of the supply connection 110 up to 16.5V, no current (<2µA @ 40°C) is drawn unless a collision occurs.

[0079] In device 102, according to an embodiment, the through-switch (T_p) is designed to provide a defined high-resistance connection between the elements (110; 230; T_kop, D1, Rg2, Rg1 and T_D1 and VH) for testing purposes.

[0080] According to one embodiment, the device 102 comprises an output protection diode (cathode) at output VH, anode at ground connection 115 for freewheeling inductive transients caused by switching operations in the safety device 104 or by inductive pulse injection into ignition circuits from the safety device 104 in the event of a crash.

[0081] According to one embodiment, the device 102 is locked in its function by monitoring the VH voltage, i.e., VH level high impedant (P_SVR=0 or high Z) can be checked as follows: VH_HZ ≈ VH_lim* (Rb2_1 II Rb2) / (Rb2_1 II Rb2+Rg1+Rg2)+0.1V - IVH_HZ*(Rb2_1 II Rb2)*(Rg1+Rg2) / (Rb2_1 II Rb2+Rg1+Rg2), e.g. VH_lim*8.57k / 9.78k+0.1-IVH_HZ*1.06k IVH_HZ supply current of the safety device in normal case (no collision) or IVH_HZ_TEST (no collision but test current consumption at VH of the safety device 104.

[0082] According to one embodiment, the device 102 can be tested for conductivity (i.e., VH level low impedant (P_SVR=0 or high Z)) by monitoring the VH voltage: VH_LZ ≈ VH_lim-VGSth_T_P - 0 * IVH_LZ_TEST without measurable dependence on a test current consumption at VH.

[0083] Typically, the voltages 222 and 226 are generated from a vehicle battery buffered by a generator. Terminal 15 / 15R is connected via a switch. In one such embodiment, a corresponding switch is arranged in a line connecting element 226 to terminal 224, for example, between element 226 and the line in Fig. 3 diodes shown.

[0084] If an embodiment includes an “and / or” connection between a first feature and a second feature, this is to be read as meaning that the embodiment according to one embodiment has both the first feature and the second feature, and according to another embodiment either only the first feature or only the second feature.

Claims

[1] Device (102) for providing an activation voltage (VH), in particular a limited, switchable (high / low-impedant) ignition high-side supply voltage, for a safety device (104) for a vehicle (100), wherein the device (102) has the following features: a supply connection (110; 220, 224, 228, 230) for applying a first supply voltage potential, an activation connection (112) in the form of an output for outputting the activation voltage (VH), a control connection (114) for reading a control signal (P_SVR) and a ground connection (115) for a second supply potential; a through-switch (T_p) with a control input, wherein the through-switch (T_p) is connected between the supply terminal (110; 220, 224, 228, 230) and the activation terminal (112), and is configured to provide a conductive, in particular low-resistance, connection between the supply terminal (110; 220, 224, 228) and the activation terminal (112) when a first signal level is applied to the control input, and to block the conductive connection between the supply terminal (110; 220, 224, 228, 230) and the activation terminal (112) when a second signal level is applied to the control input. a first control switch (T_D1) with a first terminal, a second terminal and a control input, wherein the first terminal is connected to the control input of the through switch (T_p), the second terminal to the activation terminal (112) and the control input is connected to the control input of the through switch (T_p) via a first resistor (Rc); a second control switch (T_D2) with a first terminal, a second terminal and a control input, wherein the first terminal is connected via at least a second resistor (Rb2, Rb2_1) to the control input of the first control switch (T_D1), the second terminal to a second supply voltage potential (115) and the control input via at least a third resistor (Rp1, Rp2, Rp3, Rp4) to the supply terminal (110; 220, 224, 228) and via a diode (ZD2) to the second supply voltage potential (115); and a third control switch (T_D3) with a first terminal, a second terminal and a control input, wherein the first terminal is connected to the control input of the second control switch (T_D2), the second terminal to the second supply voltage potential (115) and the control input to the control terminal (114). [2] Device (102) according to claim 1, wherein the second control switch (T_D2) is open and non-conductive when the third control switch (T_D3) is closed in response to the control signal (P_SVR) (high) received from the control terminal (114). [3] Device (102) according to one of the preceding claims, comprising two parallel connected second resistors (Rb2, Rb2_1). [4] Device (102) according to one of the preceding claims, comprising a series circuit consisting of a first parallel-connected resistor pair (Rp1, Rp3) and a second parallel-connected resistor pair (Rp2, Rp4). [5] Device (102) according to one of the preceding claims, comprising a limiting switch (T_kop) having a first terminal, a second terminal and a control input, wherein the first terminal is connected to the supply terminal (110; 230), the second terminal to the control input of the through-switch (T_p) and the control input is connected via at least a fourth resistor (Rv1, Rv2) to the supply terminal (110; 230) and via a diode (ZD1) to the second supply voltage potential (115). [6] Device (102) according to one of the preceding claims, wherein the switches (T_p, T_D1, T_D2, T_D3) are implemented as transistors. [7] Device (102) according to one of the preceding claims, wherein the through-switch (T_p) is designed as a power MOS transistor and / or the first control switch (T_D1) is designed as a bipolar transistor and / or the second control switch (T_D2) is designed as an NMOS transistor. [8] Device (102) according to one of the preceding claims, which is designed such that the device (102) is suitable for sleep airbag control units [9] Device (102) according to one of the preceding claims, wherein the through-switch (T_p) is configured to provide a defined high-resistance connection between the elements (110; 230; T_kop, D1, Rg2, Rg1 and T_D1 and VH) for testing purposes. [10] Device (102) according to one of the preceding claims, with an output protection diode having the cathode at the activation terminal (112) and the anode at the ground terminal (115) for freewheeling inductive transients caused by switching operations in the safety device (104) and / or by inductive pulse injection into ignition circuits from the safety device (104) in the event of a crash. [11] Safety device for a vehicle (100), wherein the safety device has the following features: a device (102) according to one of the preceding claims; at least one vehicle battery (222, 226) which is switched or permanently connected to the supply terminal (110; 220, 224) and the ground terminal (115) of the device (102) in order to provide a battery voltage as the first supply voltage potential against the ground terminal (115) at the supply terminal (110; 220, 224); an energy reserve device (116) which is connected to the supply terminal (110; 228, 230) and the ground terminal 115 of the device (102) in order to provide a reserve voltage as the second supply voltage potential relative to (115) at the supply terminal (110; 228, 230); and a safety device (104) which is connected to the activation terminal (112) of the device (102) in order to be supplied with ignition current in the event of a collision by a low-impedance switched limited ignition high-side supply voltage (VH). [12] Safety device according to claim 11, wherein the safety device (104) is a personal protection device. [13] Safety device according to claim 11 or 12 with at least one vehicle battery (222, 226) which is connected as a permanent supply to the supply terminal (110; 220), as well as as a switched supply to the supply terminal (110; 224) and the ground terminal (115) of the device (102) in order to provide a battery voltage as the first supply voltage potential against the ground terminal 115 at the supply terminal (110; 220, 224). [14] Method for providing an activation voltage (VH) for a safety device (104) for a vehicle (100) using a device (102) according to one of the preceding claims, wherein the method comprises the following steps: Applying (201) the supply voltages with a fixed ground reference point to the supply terminal (110; 220, 224, 228, 230) of the device (102) with the permanent ground terminal (115); and Providing (201) the control signal (P_SVR) to the control terminal (114) of the device (102). [15] Method according to claim 14, wherein in the step of applying (201) supply voltages with a fixed ground reference point are applied to the supply terminal (110; 220, 224, 228, 230) of the device (102) with the permanent ground terminal 115.

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