Intelligent semiconductor switch
By detecting the parameters of external components connected to the configuration pins and dynamically adjusting the drive signal of the intelligent semiconductor switch, the safety and robustness issues caused by fixed wiring components are resolved, ensuring the reliable operation and functional safety of the system under fault conditions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- INFINEON TECHNOLOGIES AG
- Filing Date
- 2021-02-18
- Publication Date
- 2026-05-29
Smart Images
Figure CN113315501B_ABST
Abstract
Description
Technical Field
[0001] This specification relates to the field of smart semiconductor switches, and in particular to a smart semiconductor switch having the possibility of configuring specific parameters of a smart semiconductor switch. Background Technology
[0002] Electronic switches are widely used. For example, with the increasing electrification of automobiles, more and more electronic switches are being installed in vehicles. Improved driver assistance systems and autonomous driving require high reliability. A so-called "smart semiconductor switch" typically includes one or more power transistors that function as electronic switches, as well as sensors and control electronics within the semiconductor chip. Therefore, a smart semiconductor switch may include, for example, a current measurement circuit to measure the load current of the power transistor. The current measurement can be used, for example, to implement overcurrent protection functions (e.g., overcurrent shutdown, current limiting, etc.). A smart semiconductor switch may also include a temperature measurement circuit to implement overheat protection functions.
[0003] Furthermore, smart semiconductor switches can output measured values so that these values can be processed, for example, by a microcontroller. For this purpose, known smart semiconductor switches may have diagnostic pins at which current or voltage can be output, representing a measured value or one or more parameters of the smart semiconductor switch. These parameters may, for example, represent fault codes or current values of configurable parameters, such as temperature or current thresholds.
[0004] Smart semiconductor switches can be configurable. That is, specific parameters of the semiconductor switch (e.g., current limiting thresholds, temperature thresholds, slew rate, etc.) are not fixedly preset but can be set by the user. If the smart semiconductor switch has a digital communication interface (e.g., a Serial Peripheral Interface, SPI), these parameters can be set and read relatively easily via specific control commands transmitted from, for example, a microcontroller to the smart semiconductor switch through the communication interface. In many applications, such a digital communication interface is absent or intentionally omitted to improve the robustness of the overall system. Therefore, the smart semiconductor switch can have one or more configuration pins, where resistors can be connected, for example. Here, the resistance value of the resistor determines the specific parameter values used in the smart semiconductor switch. For example, the user can determine the temperature threshold of the smart semiconductor switch, which is critical to its safety functions, by means of an external resistor connected to the configuration pin. Parameters are reliably set by means of fixed-wiring hardware and do not depend on (if necessary, software-controlled) digital transmission.
[0005] However, components with fixed wiring can still fail for various reasons (e.g., incorrect solder joints), or their characteristics (e.g., resistance values) may change over time, which in some cases may alter safety-critical parameters of the smart semiconductor switch. Regarding applicable standards for functional safety (ISO 26262), there is a need to improve existing approaches to the functional safety and robustness of smart semiconductor switches, particularly for applications. Summary of the Invention
[0006] A circuit capable of operating as a smart semiconductor switch is described. According to one embodiment, the circuit includes a power supply pin, an output pin for connecting a load, and a configuration pin. The circuit also includes a semiconductor switch connected between the power supply pin and the output pin, and is designed to establish or block a current path between the power supply pin and the output pin based on a drive signal. Control circuitry is designed to generate a drive signal for the semiconductor switch, taking into account a first parameter, and to set the first parameter based on component parameters of an external component connected to the configuration pin. If the component parameter is less than a first threshold, the first parameter is set to a first standard value; and if the component parameter is greater than a second threshold, the first parameter is set to a second standard value.
[0007] Furthermore, a method for a smart semiconductor switch is described. According to one embodiment, the method includes setting a first parameter based on component parameters of an external component connected to a configuration pin. Here, if the component parameter is less than a first threshold, the first parameter is set to a first standard value, and if the component parameter is greater than a second threshold, the first parameter is set to a second standard value. Furthermore, the method also includes generating a drive signal for the semiconductor switch, taking the first parameter into account. Attached Figure Description
[0008] In the following description, embodiments are explained in more detail with reference to the accompanying drawings. These drawings are not necessarily to scale, and the embodiments are not limited to the aspects shown. Rather, the focus is on illustrating the principles on which the embodiments are based. Wherein:
[0009] Figure 1 An exemplary application of a smart semiconductor switch is shown, wherein the smart semiconductor switch is driven by a microcontroller.
[0010] Figure 2 An embodiment of a smart semiconductor switch is shown, wherein parameters are set according to the component parameters of an external component connected to a configuration pin.
[0011] Figure 3 and Figure 4 An example is shown showing the relationship between component parameters of an element connected to a configuration pin and parameters to be set for a smart semiconductor switch.
[0012] Figure 5 The encoding of information in the diagnostic current is shown.
[0013] Figure 6 A flowchart of an example method for configuring the operating parameters of a smart semiconductor switch is shown.
[0014] Figure 7 It shows that it can be used Figure 2 An example of a possible implementation of the parameter reading circuit used in a smart semiconductor switch.
[0015] Figure 8 It shows that it can be used Figure 2 An example of a possible implementation of the gate driver and current limiting circuit used in a smart semiconductor switch.
[0016] Figure 9 Showing more details Figure 7 It is part of the circuit.
[0017] Figure 10 It shows that it can be used Figure 2 An example of a possible diagnostic output circuit used in a smart semiconductor switch. Detailed Implementation
[0018] Figure 1 A simple example of the use of a smart semiconductor switch 1 in an electronic control unit (ECU) is shown. In the example shown, the ECU has a microcontroller unit (MCU) 2, which is designed to drive the smart semiconductor switch 1 to, for example, turn on and off a load. It should be understood that... Figure 1 resistor R L This refers to any electrical load. In automotive applications such as driver assistance systems, this load could be, for example, a radar system, a camera, or any other electrical subsystem.
[0019] exist Figure 1In the example, the smart semiconductor switch has a power supply pin VS, a ground pin GND, an output pin OUT, a first input pin IN, a second input pin DEN (diagnostic pin), a diagnostic output pin IS, and a configuration pin OC. It should be understood that this is not an exhaustive list. The smart semiconductor switch 1 may, for example, have multiple output channels with multiple output pins or multiple configuration pins. In some embodiments, as described above, the smart semiconductor switch may also have a digital communication interface with corresponding input / output pins. The pin configuration depends on the chip housing used, in which the semiconductor chip integrating the smart semiconductor switch is arranged. In SMD housings (SMD packages), the pins are designed as solder pins. In other types of chip housings, the pins may be designed as solder balls.
[0020] For example, the power supply voltage V provided by the car battery S The signal is fed to the power supply pin VS. A power transistor included in the smart semiconductor switch 1 couples the power supply pin VS to the output pin OUT. Therefore, when the power transistor is turned on, power is supplied to the load R. L Provide power supply voltage V S (Ignore the voltage drop at the power transistor), and the corresponding load current i OUT It can flow through the transistor and the load R L The ground pin GND is connected to ground GND2, which does not need to be the same as the ground GND1 used for microcontroller 2. The input signal V received at the input pin IN... IN Indicates whether the power transistor should be turned on or off. Input signal V IN Typically, this is a binary logic signal (with "high" and "low" levels), which is generated by microcontroller 2 in the example shown. This is achieved by input signal V... IN The voltage level is set to high or low, and the microcontroller 2 can turn the smart semiconductor switch 1 on or off.
[0021] The diagnostic function will be discussed in detail below. This is achieved by applying an appropriate logic level (diagnostic request signal V) to the diagnostic pin DEN. DEN This can cause the smart semiconductor switch 1 to output diagnostic information (e.g., current measurement, fault code, etc.) at the diagnostic output pin IS. In this example, the smart semiconductor switch outputs a diagnostic current i containing diagnostic information at pin IS. S Diagnostic current i S The resistor R is coupled between pin IS and ground GND1. S The corresponding voltage drop i is generated on S ·R SThe voltage drop can be received and digitized, for example, at the analog input of the microcontroller 2.
[0022] As described above, the smart semiconductor switch 1 may have one or more configuration pins. In this example, a configuration pin OC is provided to set the current threshold used in the smart semiconductor switch 1. This operating parameter (current threshold in this example) is determined by the component parameters (e.g., resistance value) of an external component (e.g., a resistor) connected to the configuration pin OC.
[0023] Figure 2 An embodiment of the smart semiconductor switch is shown in more detail. According to... Figure 2 Power transistor T L The load current path connects the power supply pin VS to the output pin OUT. In the example shown here, the power transistor is designed as a MOS transistor; in this case, the load current path is a drain-source current path. Power transistor T L Configured as a high-side switch, i.e., power transistor T L Arranged on load R L and power supply voltage V S Between. In this respect, it should be noted that the scheme described herein can be easily adapted to smart semiconductor switches with low-side switches. Therefore, in some embodiments, the power transistor is positioned between the output pin OUT and the ground pin GND. Both p-channel and n-channel MOS transistors can be used. Other types of transistors, such as bipolar transistors, can also be used.
[0024] Figure 2 The image shown is used to measure the load current i. OUT The current measurement circuit is based on a known sensing FET scheme. Therefore, the measuring transistor T... S (Sensing transistor) and power transistor T L Coupling causes the power transistor T L The measuring transistor and the measuring transistor operate at essentially the same operating point. In this case, the current flowing through the measuring transistor T... S current i CS With the current flowing through power transistor T L current i OUT Roughly proportional, thus the current i CS It can be used as current i OUT The measured value. The scaling factor k = i CS / i OUT Basically composed of transistor T S and T L The effective area ratio is determined by the current i. CS Cause resistor R CSVoltage drop V across the terminals CS The resistor R CS It can be connected to transistor T S Between the source and ground. Therefore, the voltage V CS It is also basically related to the output current i OUT It is proportional and can be used as a current measurement value. It should be understood that... Figure 2 The current measurement circuit shown is only a simplified example, and the actual implementation can be significantly more complex depending on the application. However, current measurement circuits based on the sensing FET principle are known in themselves and will not be described further here. Other types of current measurement can also be used, such as those with power transistors T. L A simple current-measuring resistor coupled together.
[0025] Power transistor T L Typically driven by a driver circuit 11, which is referred to as a gate driver in the case of a MOS transistor. In the example shown, the gate driver 11 receives a logic signal V1, which indicates whether the power transistor T should be turned on or off. L Gate driver 11 generates an appropriate gate voltage V based on the logic signal V1. G Or an appropriate gate current to turn the power transistor T on or off. L The structure and operating principle of the gate driver circuit are known, and therefore will not be discussed in detail here. The gate driver circuit 11 can also be coupled to an overcurrent protection circuit 12, which is designed, for example, to limit the drive of the gate electrode to such that the resulting load current i OUT Limited to the maximum value i OUT,max This maximum value depends, for example, on the current threshold TH. OC Even though the gate driver 11 and overcurrent protection circuit 12 are shown as separate modules in the example shown, the overcurrent protection circuit 12 can still be included in the gate driver 11. When the current measurement value V CS Indicator load current i OUT The maximum value i has been reached. OUT,max At that time, the current limiting function is active.
[0026] In another embodiment, overcurrent shutdown is provided instead of current limiting. For this purpose, the overcurrent protection circuit 12 checks the load current i. OUT Has the predefined threshold i been reached or exceeded? TRIP (Commonly referred to as "trip current"). Then, the overcurrent protection circuit 12 can transmit a signal (overcurrent signal OC). EN Notify the gate driver that the threshold TH has been reached or exceeded. OCThe gate driver then turns off transistor T. L Alternative ground, overcurrent signal OC EN This can cause the driver logic 10 to blank the logic signal V1 (and, for example, set the logic signal V1 low) to turn off the transistor T. L .exist Figure 2 The diagram also shows a temperature sensor 17, which is designed to measure the chip temperature. Based on the measured chip temperature, the driver logic can trigger a semiconductor switch T. L Overheat shutdown. In some embodiments, multiple temperature sensors are provided to measure the temperature difference at the chip. Excessive temperature differences may also necessitate shutting down the semiconductor switch T. L By using the load transistor T L When switched on, the voltage drop across the transistor's load current path (i.e., the drain-source voltage V) will be reduced. DS ) and the corresponding threshold V DSmax Overcurrent shutdown can also be achieved through comparison. If the current exceeds this threshold (V)... DS ≥V DSmax Then transistor T L Turned off (overcurrent turn-off). In this regard, the threshold for overcurrent turn-off can also be transistor T. L Maximum drain-source voltage V when switched on DSmax .
[0027] The aforementioned driver logic 10 is a logic circuit that receives an input signal V. IN and V DEN And according to the input signal V IN and V DEN The logic circuit 10 can perform certain control functions in response to the input signal V. IN A high-level signal generates a corresponding high-level control signal V1 to turn on the power transistor T. L However, if necessary, such as due to an identified overcurrent condition or overheating, logic circuit 10 can prevent the turn-on transistor T from being triggered or triggering the turn-off transistor T. L .
[0028] Parameters can be configurable to adapt the smart semiconductor circuit to the desired application; parameters such as current limiting and overcurrent shutdown (e.g., due to condition V) are used. DS ≥V DSmax Thresholds for overheat shutdown, etc. Figure 2 In the example shown, the threshold TH used for current limiting OC It is configurable. It should be understood that other parameters, such as the temperature threshold, can also be configured in the same way. As mentioned above, the threshold TH...OC This is determined by the component parameters of the part connected to the configuration pin OC. In the example shown, the component parameter is resistor R. OC The resistance value. In Figure 2 In the example shown, resistor R OC The first terminal is connected to the configuration pin OC, and the resistor R OC The second terminal of resistor R is grounded. It should be understood that resistor R... OC It can also be connected to the configuration pin OC and the applied power supply voltage V. S Between the circuit nodes. Alternatively, resistor R can also be used. OC Connect between the configuration pin OC and any (constant) reference voltage.
[0029] The parameter readout circuit 13 is designed to be based on the resistance value R. OC To generate representations of the desired operating parameters (e.g., threshold TH). OC The parameter readout circuit 13 can be designed to output a test current i at the configuration pin OC for this purpose. PAR And adjust the test current i PAR This results in a voltage V0 = R OC ·i PAR This corresponds to a predefined constant value (e.g., V0 = 0.5V). Therefore, the test current i PAR Clearly express the resistance value R OC (i PAR =V0 / R OC ), and the parameters sought (e.g., threshold TH) OC ) can be based on the test current i PAR To set. It should be understood that in other examples, the current i PAR It can also be adjusted to be constant, and the resulting voltage V0 represents the resistance value R. OC .according to Figure 2 Threshold TH OC It is provided to the overcurrent protection circuit 12, and is used by the overcurrent protection circuit 12 to control the output current i OUT Current limitation. That is, the threshold TH. OC The maximum output current i was determined. OUT,max .
[0030] exist Figure 2 The diagram also shows a diagnostic output circuit 14 (sensing output circuit), which is designed, for example, to output a diagnostic current i S Diagnostic information is output in the form of [format]. Based on the state of intelligent semiconductor switch 1, the diagnostic current i is [value]. SIt can have different meanings. If the power transistor T L Connect (i.e., input signal V) IN (with a high level) and diagnostic request signal V DEN If a high level is displayed, the diagnostic current i S Indicates the current measurement signal i CS If power transistor T L Disconnect (i.e., input signal V) IN (With a low level or an error) and diagnostic request signal V DEN A high level indicates a status information, such as a fault code, in the diagnostic current. Therefore, the diagnostic output circuit 14 can have multiple controllable current sources, which can be activated and deactivated by driver logic 10 to output the desired current i at the diagnostic output pin IS. S .
[0031] Figure 3 An example is shown in the component connected to the configuration pin (in Figure 2 In the example, the resistor is R. OC The component parameters and the parameters to be set for the intelligent semiconductor switch TH OC The relationship between these factors can be used to set the maximum output current i. OUT,max , for use in i OUT,max,1 and i OUT,max,2 The current limit between them. In the embodiment described herein, resistor R OC The corresponding resistance value varies between 5kΩ and 100kΩ. Here, 100kΩ corresponds to the maximum output current i. OUT,max,1 And 5kΩ corresponds to the maximum output current i OUT,max,2 .
[0032] Figure 3 The characteristic curve shown can continue on both sides. That is, for the example shown, a resistance greater than 100kΩ will result in a current limit of less than i. OUT,max,1 The maximum current, and a resistance less than 5kΩ will cause the current to be limited to greater than i. OUT,max,2 The maximum current. Both can lead to dangerous situations, as the current limit will become ineffective (maximum current too high) or the load will no longer be able to operate properly (maximum current too low). This is especially true when resistor R... OC This situation can occur when a fault arises and creates a short circuit or an open circuit. An open circuit can be caused, for example, by a poorly soldered joint.
[0033] As mentioned above, for the functional safety of the system, it is important that a single fault, such as a faulty (or incorrectly connected) resistor R, is prevented. OCThis will not render the entire system unusable. Therefore, even in the event of a fault, the entire system should remain operational (fail-safe function). Regarding parameter configuration using externally connected components (resistors), Figure 4 The characteristic curves in the diagram illustrate the solution to the aforementioned problem. According to this embodiment, the intelligent semiconductor circuit 1 (e.g., parameter readout circuit 13, see...) Figure 2 It is designed such that if the component parameter is less than a first threshold (e.g., R), OC <R OCmin R OCmin ≈5kΩ), then the parameter to be set (for example, representing the maximum current i) will be... OUT,max Threshold TH OC ) is set to the first standard value, and if the component parameter is greater than the second threshold (e.g., R) OC >R OCmax R OCmax If the resistance is approximately 100kΩ, then the parameter to be set will be set to the second standard value. Figure 4 In the example shown, the first standard value and the second standard value are the same, and are determined by i OUT,max,default This indicates that the first and second standard values can differ, but in i... OUT,max,1 and i OUT,max,2 Within the range.
[0034] Using according to Figure 4 The characteristic curve can ensure that relevant parameters (i.e., such as the current threshold i) are accurate. OUT,max ) Remain within the "normal" range, which is the range even for resistor R OC The load can continue to operate even in the event of a fault (e.g., short circuit or open circuit) (with limitations if necessary). Furthermore, the intelligent semiconductor circuit 1 (e.g., parameter reading circuit 13, see...) Figure 2 It can be designed to detect element parameters (e.g., resistance R). OC The value is less than the first threshold or greater than the second threshold, and is subject to a request (see [link]). Figure 2 Diagnostic request signal V DEN At the diagnostic output pin IS, the corresponding diagnostic current i S The information is output in the form of [format].
[0035] Figure 5 Diagnostic current i is shown S The information in the code is encoded according to the diagnostic current based on the request (diagnostic request signal V). DEN (When at a high level) is output at pin IS. Figure 5This is just an illustrative example with four different current levels. Depending on the application, more or fewer current levels can be used for information encoding. Figure 5 The example in the example involves a situation where a low level (power transistor T) is applied at the input pin IN. L (Disconnected), and a high level is applied at the input pin DEN (diagnostic request). In this case, the diagnostic current i S have Figure 5 One of the four values shown. In the example shown, the lowest current value indicates a general error, which could be triggered, for example, by overheating. (From bottom to top) The second current level indicates the resistor R. OC (see Figure 2 The current is too low and a short circuit may exist. The third current value indicates the following fault condition, in which the voltage V at the output pin OUT is... OUT Too high, that is, when the difference V S -V OUT Less than threshold V DS,min At that time, the highest fourth current value indicates the resistor R. OC (see Figure 2 The size is too large and there may be open circuits. Microcontroller (see...) Figure 1 It can assess diagnostic current and, for example, notify the higher-level control unit and / or initiate certain emergency measures (e.g., bring the autonomous vehicle to a reliable stop and park).
[0036] exist Figure 6 The flowchart illustrates, and is summarized below, an example of a method implemented in a smart semiconductor switch for configuring operating parameters (e.g., current threshold) of the smart semiconductor switch. Figure 6 First, determine the external component R that is connected to the configuration pin. OC The values of the component parameters (e.g., the test current i mentioned above) PAR See Figure 2 (See also) Figure 6 (Step S1). As described above, for example, the test current i can be... PAR The resistor R fed into the configuration pin OC is connected to the resistor R. OC In, and the test current i PAR The adjustment is made so that the voltage V0 at the configuration pin OC presents a predefined value. In this case, the test current i PAR It can be considered as a resistor R OC The measured value.
[0037] Then, check the component parameter R. OC Is it less than the first threshold R? OCmin (see Figure 6 (Step S2). If the component parameter ROC Less than the first threshold R OCmin (in resistor R) OC If a short circuit is detected, the operating parameter to be configured will be set to the first standard value (see [reference]). Figure 6 Step S4, standard value i OUT,max,default If the component parameter R OC Not less than the first threshold R OCmin Then check the component parameter R. OC Is it greater than the second threshold R? OCmax (see Figure 6 (Step S3). If the component parameter R OC Greater than the second threshold R OCmax (in resistor R) OC If an open circuit is detected, the operating parameter to be configured will be set to the second standard value (see [reference]). Figure 6 Step S5, standard value i OUT,max,default If the component parameter R OC Not greater than the second threshold R OCmax The measured component parameters determine the desired operating parameters (see...). Figure 6 (Step S6). In other words, the sought operating parameters (e.g., current threshold i) OUT,max ) is a component parameter (resistance R) OC The function is called ). An example of this function is in Figure 4 As shown in the diagram. Then, drive signals for the power transistors (e.g., gate voltage V) are generated. G ), which takes into account the configured operating parameters (see Figure 6 (Step S7). Under current constraints, a gate voltage is generated, causing the load current i OUT Unable to increase to the maximum value i determined by the running parameters OUT,max The above. As mentioned above, this maximum value is one of two standard values, or (within predetermined limits) depends on the resistance value of the external resistor (e.g., for R). OCmin <R OC <R OCmax i OUT,max ~1 / R OC ).
[0038] Furthermore, as described above, the method may include the step of outputting a diagnostic signal (e.g., a diagnostic current i) based on this step. S The diagnostic signal is based on the diagnostic request signal (see Diagnostic Request Signal). Figure 2 The signal V at the input pin DEN DEN Indicates component parameters (e.g., resistance R) OC Is it less than the first threshold R? OCmin Or greater than the second threshold ROCmax (see Figure 5 ).
[0039] In the embodiments described herein, the maximum current i used in the current limit is illustrated as an example of a configurable parameter. OUT,max Additionally or alternatively, other parameters can be configured in the same manner, such as overheat threshold, maximum temperature difference at the semiconductor chip (temperature difference), threshold for overcurrent shutdown (trip current), threshold for the estimated cable temperature of the cable connected to the output pin, etc.
[0040] Figure 7 It shows Figure 2 An example of a possible implementation of the parameter reading circuit 13 of the smart semiconductor switch shown. Figure 7 The configuration pin OC and the ground pin GND are shown. (As already referenced...) Figure 2 As explained, the grounding pin and the grounding potential V GND Connect, and resistor R OC It is externally connected to the configuration pin OC. The parameter readout circuit 13 is designed to read the voltage V0 at the configuration pin OC (and therefore the resistor R). OC The voltage drop across the terminals is set to a constant predefined reference value V. REF (For example, V) REF =0.5V). Therefore, the current i output at the configuration pin OC is... PAR With resistance R OC Inversely proportional, that is, i PAR =V REF / R OC .
[0041] Current i is provided by transistor T1 PAR The transistor T1 is coupled to the configuration pin OC such that the load current path of transistor T1 is connected to resistor R. OC Series connection. In the example shown, the control electrode (gate electrode in the case of a MOS transistor) of transistor T1 is driven by operational amplifier OA1, such that the voltage V0 at the configuration pin OC is equal to the reference voltage V. REF For this purpose, voltage V0 is fed back to the inverting input of operational amplifier OA1, while the reference voltage V... REF The differential voltage V at the input of operational amplifier OA1 is applied to the non-inverting input. Operational amplifier OA1 drives transistor T1, causing the differential voltage V at the input of operational amplifier OA1 to... REF -V1 is approximately zero volts, which makes V1 ≈ V REF Zener diode D Z It is optional and prevents overvoltage at the OC pin. In this regard, it should be reiterated that the resistance value R... OCThis represents the parameter to be configured, and therefore i PAR It also indicates the parameters to be configured.
[0042] Current i PAR =V REF / R OC The current is fed to current comparator 131, which is designed to: convert current i PAR With lower threshold i LO and upper threshold i HI Compare (where i) LO HI The binary (logic signal) LO indicates whether condition i is met. PAR LO And the binary signal HI indicates whether condition i is met. PAR >i HI Limiting circuit 132 prevents the current limiting value i from being used for current limiting. OUT,max Too small or too large. Under normal circumstances, i OUT,max =i PAR However, if—for example, due to resistor R— OC Short circuit - current i PAR Too large (i.e., i) PAR >i HI If the limiting circuit 132 outputs a standard value i, then... OUT,max =i OUT,max,2 As the limit value i OUT,max If—for example—due to an open circuit at the configuration pin OC (i.e., R) OC (Too high) - Current i PAR Too small (i.e., i) PAR LO If the limiting circuit 132 outputs a standard value i, then... OUT,max =i OUT,max,1 As the limit value i OUT,max In the following text, reference will be made to... Figure 9 An exemplary implementation of the current comparator 131 and the limiting circuit 132 will be discussed in more detail. In this example, the external resistor R... OC It is connected between the configuration pin OC and ground GND. It should be understood that, in another embodiment, resistor R... OC It can also be connected to the configuration pin OC and the power supply voltage node (on which a voltage V is applied). S Between ), in this case, only slight modifications are needed to the parameter readout circuit 13 (e.g., replacing the n-channel transistor T1 with a complementary transistor, etc.).
[0043] Figure 8 It shows Figure 2 An example of a possible implementation of the gate driver 11 and current limiting circuit 12. The current limiting circuit 12 is designed such that, according to the limit value i OUT,max To limit the output current i of the smart semiconductor switch OUT . Figure 8 This illustrates a power transistor T that couples the power supply pin VS and the output pin OUT. L and already referenced Figure 2 The current measurement transistor T under discussion S The gate driver 11 mainly includes a level shifter 112 and an output stage 111. The level shifter 112 "shifts" the logic signal V1 into the floating power domain of the gate driver 11. The output stage 111 outputs the power transistor T based on the level-shifted logic signal. L Provide the corresponding gate signal V G In the example shown, the gate driver 11 also includes a charge pump that draws power from a supply voltage V. S A higher power supply voltage V is generated in the process. CP Utilizing this higher power supply voltage V CP The output stage 111 and the level shifter 112 are powered. The structure and operating principle of the gate driver 11 are known, so they will not be discussed in detail here.
[0044] In this example, the overcurrent protection circuit 12 essentially functions as a current limiter. The overcurrent protection circuit 12 includes an operational amplifier OA. LIM When by transistor T L Provided output current i OUT To achieve the result of current i OUT,max When the value is represented, the operational amplifier OA LIM Coupled to the output of gate driver 11 and converting the gate voltage V G "Clamping". The structure and working principle of current limiting are known, so they will not be discussed in detail here. In this example, operational amplifier OA LIM "See" voltage V at its input terminal CS =R CS ·i CS and voltage R CS ·i OUT,max The voltage R is generated by means of a resistor connected to the output branch of the current mirror 120. CS ·i OUT,max The current mirror 120 can mirror the current i OUT,max (From limiting circuit 132, see reference) Figure 7 The current mirror 120 is also used to convert voltage R CS ·iOUT,max Shift to the power supply domain of gate driver 11 (power supply voltage V) CP Reference is transistor T L (source voltage).
[0045] Figure 9 Showing more details Figure 7 Part of the circuit, namely, current comparator 131 and limit circuit 132. According to Figure 9 The current comparator 131 includes a current mirror 1310, which has a transistor T in the input branch. A And transistor T in the three output branches B T C and T D In this example, the current mirror 1310 is designed so that all three outputs provide the same current i. PAR The first and second output terminals of the current mirror are each coupled to a current source (source current i). HI or i LO If the output current i of the corresponding output branch of the current mirror 1310 PAR Less than the corresponding source current i HI or i LO If the voltage at the corresponding output terminal of the current mirror is high, then the voltage at the corresponding output terminal of the current mirror 1310 will be high. Conversely, if the output current i of the corresponding output branch of the current mirror 1310 is high... PAR Greater than the corresponding source current i HI or i LO If the voltage at the corresponding output terminal of the current mirror is low, then the voltage at that terminal is low. Buffers 1313 (inverting) and 1314 (non-inverting) are connected to the corresponding output terminals. Therefore, the output signals HI and LO of buffers 1313 and 1314 indicate whether condition i is met. PAR >i HI and i PAR LO The third output branch also provides current i. PAR The current i PAR It is fed to the limiting circuit 132 via another current mirror 1315. The various implementation possibilities of the current comparator are known by themselves, and therefore will not be described in detail here. Figure 9 This contains only illustrative examples, where other implementations are also possible.
[0046] The limiting circuit 132 is designed such that if two conditions i PAR >i HI and i PAR LO None of them satisfy (i.e., current i) PAR In the value i LO and i HI Between), the output (multiple mirror images) current i PAR As the limit value i OUT,max If condition i is satisfied PAR LO Then the output current i OUT,max,1 As the limit value i OUT,max If condition i is satisfied PAR >i HI Then the output current i OUT,max,2 As the limit value i OUT,max A standard value i can be provided through a current source. OUT,max,1 and i OUT,max,2 In this example, the configured value i is achieved by using a switch driven according to the output signals HI and LO of buffers 1313 and 1314. PAR Compared with the standard value i OUT,max,1 and i OUT,max,2 Switching between them. As mentioned above, the standard value i OUT,max,1 and i OUT,max,2 The same can be used. In this case, the implementation of the limiting circuit 132 is simplified. As a result, the limiting circuit 132 ensures that the limit value i is the same. OUT,max Always in i HI and i LO Between, and—if this is not the case—the standard value is instead used for subsequent current limits.
[0047] Figure 10 It shows Figure 2 An example of a possible implementation of the diagnostic output circuit 14. In the example shown, the diagnostic output circuit 14 has a multiplexer MUX and multiple current sources that provide current levels i S (FAULT), i S (R OC <R OCmin ), i S (R OC >R OCmax ) and i S (V S -V OUT <V DSmin Additionally, the current i provided by the current measurement circuit CS... CS (If necessary, via one or more current mirrors) can be fed to the input of the multiplexer MUX. Driver logic 10 (see...) Figure 2 The system is designed to either not output a specific current or output a specific current at the diagnostic pin IS, depending on the state of the smart semiconductor switch. In this example, the select signal CTL fed to the multiplexer is generated by driver logic 10 and can be particularly dependent on the input signal V.IN and V DEN And logic signals HI and LO (see Figure 7 ).
[0048] It should be understood that the examples shown in the accompanying drawings are merely exemplary implementations of the illustrated functions. Those skilled in the art can readily design other implementations that substantially perform the same functions. For example, parameter reading circuit 13 (see...) Figure 2 and Figure 7 The desired component parameters can also be recorded digitally. For this purpose, a digital-to-analog converter (DAC) with a current output can be coupled to a configuration pin OC, allowing the DAC's output current to flow through an external resistor R. OC Then, the digital-to-analog converter can be digitally controlled so that the voltage at the configuration pin OC presents the desired value V. REF Therefore, the input register of the digital-to-analog converter contains a digital value representing the current flowing through resistor R. OC The current, and therefore also the resistance value. The diagnostic output circuit 14 can also alternatively be implemented using a digital-to-analog converter with a current output terminal, wherein the logic circuit 10 digitally determines the current i to be output. S As mentioned above, many different current measurement possibilities are also known (see [link to documentation]). Figure 2 Current measurement circuit (CS).
Claims
1. A circuit having the following features: Power supply pin (VS) and pin for connecting load (R) L The output pin (OUT) and configuration pin (OC); A semiconductor switch (T1) is connected between the power supply pin (VS) and the output pin (OUT), and is designed to respond to a drive signal (V). G Establish or block a current path between the power supply pin (VS) and the output pin (OUT); The control circuit (CTL) is designed to: take into account the first parameter (i) OUT,max In the case of ), the drive signal (V) for the semiconductor switch (T1) is generated. G ), and according to the component parameters (R) of the external component connected to the configuration pin (OC). OC ) to set the first parameter (i OUT,max ), where if the component parameter (R) OC ) less than the first threshold (R) OCmin ), then the first parameter (i OUT,max ) is set to the first standard value (i OCmax ), and if the component parameters (R) OC ) greater than the second threshold (R) OCmax ), then the first parameter (i OUT,max ) is set to the second standard value (i OCmin ); The diagnostic pin (IS), wherein the control circuit (CTL) is also designed to output a diagnostic signal (i S The diagnostic signal is based on the diagnostic request signal (V). DEN ) indicates the component parameters (R) OC Is it less than the first threshold (R)? OCmin ) or greater than the second threshold (R) OCmax ).
2. The circuit according to claim 1, Where the first parameter (i) OUT,max ) is the maximum output current, and the component parameter (R) is mentioned above. OC ) is the resistance value of the external resistor connected to the configuration pin (OC).
3. The circuit according to claim 1 or 2, wherein the control circuit (CTL) further comprises: The parameter reading circuit (13) is designed to: acquire the parameter (R) representing the component parameter. OC The numerical value of the component parameter (R) or the value representing the component parameter (R) can be obtained. OC The current (i) PAR ).
4. The circuit according to claim 1, Where the first parameter (i) OUT,max ) is the overheat threshold, temperature difference, and threshold used for overcurrent shutdown (i TRIP V DSmax ), or the estimated cable temperature threshold for the cable used to connect to the output pin (OUT).
5. The circuit according to claim 1 or 2, further comprising: Used to receive input signals (V) IN The first input pin (IN) of ) The control circuit (CTL) is also designed to: based on the input signal (V) IN ) to generate the drive signal (V) for the semiconductor switch (T1). G ), so that according to the input signal (V) IN (T1) is used to turn the semiconductor switch (T1) on or off.
6. The circuit according to claim 5, wherein the diagnostic signal (i S It also depends on the input signal (V) IN ).
7. The circuit according to claim 5, The diagnostic signal (i) S ) is the diagnostic current, if the input signal (V) IN If the semiconductor switch (T1) is disconnected, the current value of the diagnostic current indicates the component parameter (R). OC Is it less than the first threshold (R)? OCmin ) or greater than the second threshold (R) OCmax ).
8. The circuit according to claim 5, The diagnostic signal (i) S ) is the diagnostic current, if the input signal (V) IN If the semiconductor switch (T1) is turned on, the current value of the diagnostic current represents the load current (i) of the semiconductor switch (T1). L ).
9. The circuit of claim 2, wherein the control circuit (CTL) has a current limiting circuit coupled to the semiconductor switch (T1), the current limiting circuit being designed to limit the load current (i) of the semiconductor switch (T1) to... L The current is limited to the maximum output current.
10. A method for using a semiconductor switch, comprising: Based on the component parameters (R) of the external component connected to the configuration pin (OC). OC To set the first parameter (i) OUT,max ), where if the component parameter (R) OC ) less than the first threshold (R) OCmin ), then the first parameter (i OUT,max ) is set to the first standard value (i OCmax ), and if the component parameters (R) OC ) greater than the second threshold (R) OCmax ), then the first parameter (i OUT,max ) is set to the second standard value (i OCmin ), Considering the first parameter (i) OUT,max In the case of ), a drive signal (V) is generated for the semiconductor switch (T1). G ), Detect the component parameters (R) OC Is it less than the first threshold (R)? OCmin ) or greater than the second threshold (R) OCmax ),as well as Output diagnostic signal (i S The diagnostic signal is based on the diagnostic request signal (V). DEN ) indicates the component parameters (R) OC Is it less than the first threshold (R)? OCmin ) or greater than the second threshold (R) OCmax ).
11. The method according to claim 10, Where the first parameter (i) OUT,max ) represents the maximum load current of the semiconductor switch (T1), wherein the component parameter (R) OC ) is the resistance value of the resistor connected to the configuration pin (OC).
12. The method of claim 11, further comprising: The current (i) PAR ) fed into the resistor (R) OC In ), the resistor (R) is made so that OC The voltage (V0) at point ) represents the target value (V REF ), If the fed current is within a predefined range, then the first parameter (i) OUT,max ) by the fed current (i PAR )Sure.
13. The method according to claim 12, Where the fed current (i PAR If the first parameter (i) is within the predefined range, then OUT,max ) corresponds to the first standard value (i OUT,max,1 ), and if the fed current (i PAR If the first parameter (i) is above the predefined range, then OUT,max ) corresponds to the second standard value (i OUT,max,2 ).