Soft shutdown control circuit and method in isolation driver chip, isolation driver chip

Abstract

The embodiments of the present disclosure provide a soft-off control circuit and method in an isolated driver chip, as well as an isolated driver chip. The soft-off control circuit, upon detecting desaturation of an external power device, generates a soft-off signal through a driver to control the external power device to perform a soft-off. When the soft-off behavior is not completed, the driver side latches the received input signal and selects a first frequency signal to transmit to the logic side to shield the reset signal on the logic side. After detecting completion of the soft-off behavior, the driver side releases the input signal and selects a second frequency signal to transmit to the logic side to restore the response to the reset signal and resume normal operation. This solves the problem in the prior art of open-loop control that simply controls soft-off through a fixed time period, which may cause damage to the device by not shutting down and then turning it on again.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to the field of chip protection technology, and in particular, to a soft shutdown control circuit and method in an isolation driver chip, and an isolation driver chip. Background Art

[0002] In existing isolation driver chips, the overcurrent / desaturation condition of the driven external power device is usually the highest priority response behavior. When an overcurrent / desaturation condition occurs, the driver circuit will take soft shutdown measures, that is, the gate charge is released with a current smaller than the normal shutdown current to prevent sudden shutdown at an excessively high current level, resulting in a large di / dt voltage overshoot and damage to the power device.

[0003] The specific implementation of soft shutdown measures in the existing technology is as follows: After detecting an overcurrent or desaturation condition in a power device, the driver side of the isolated driver chip typically immediately enters a soft shutdown state, shutting off the gate of the external power device with a smaller current. Simultaneously, the driver side uses the isolation channel to send a high-frequency pulse wave to the logic side. After receiving this high-frequency pulse signal, the logic side decodes the nFLT logic to indicate overcurrent or desaturation, and generates a blanking time. During this blanking time, the chip system does not respond to the nFLT state reset signal from the logic side, nor does it transmit the received gate drive signal to the driver side.

[0004] Regarding the soft shutdown implementation method in the above-mentioned prior art, the inventors found that using only a fixed time period to control the soft shutdown behavior is open-loop and unsafe, which can cause damage to the device and even damage the entire industrial system or complete equipment where the isolation driver chip is located. For example, when the system has not completed the soft shutdown within the blanking time due to various reasons, the open-loop processing method can directly reset the nFLT state and output a signal to turn on the power device, causing potential damage risks. For example, in a more severe case, if the logic side fails to decode the nFLT logic based on the high-frequency pulse signal within a fixed time, the logic side will not show any abnormality. When the driver side has entered the soft shutdown state, it can still send a drive signal normally to turn on the external power device, further causing damage to the device, which may have serious consequences for the industrial system and the complete equipment. Summary of the Invention

[0005] The embodiments described herein provide a soft-off control circuit and method in an isolation driver chip, and an isolation driver chip, in order to solve the problem that the soft-off control implementation method in the existing isolation driver chip may cause external power devices to be damaged by turning on again without being turned off.

[0006] According to a first aspect of the present disclosure, a soft-shutdown control circuit in an isolation driver chip is provided, wherein the isolation driver chip is used to drive an external power device. When desaturation occurs in the external power device, the soft-shutdown control circuit performs soft-shutdown control on the external power device. The soft-shutdown control circuit includes: a desaturation detection module, a desaturation enable signal generation module, a driver, a soft-shutdown detection module, a latch, and a multiplexer. The desaturation detection module is configured to perform desaturation detection on the external power device after the external power device is turned on, and obtain a desaturation indication signal indicating whether desaturation occurs; the desaturation enable signal generation module is configured to generate the desaturation enable signal according to the desaturation indication signal and the output signal of the latch, and when the desaturation indication signal is at a level indicating that desaturation occurs, the control module the desaturation enable signal is at an effective level; the driver is configured to receive the output signal of the latch, and generate a soft shutdown feedback signal and a soft shutdown signal for shutting down the external power device according to the output signal and the desaturation enable signal; the soft shutdown detection module is configured to detect a soft shutdown state according to the desaturation enable signal and the soft shutdown feedback signal, obtain a soft shutdown state indication signal for indicating whether the soft shutdown is completed, and control a desaturation latch signal according to the soft shutdown state indication signal; the latch is configured to receive an input signal from the driving side of the isolation driver chip, and latch or release the input signal according to the desaturation latch signal, and output it to the driver, and latch the input signal when the desaturation latch signal is at a first level, and release the input signal when the desaturation latch signal is at a second level;

[0007] The multiplexer is configured to select, when the desaturation latch signal is at a first level, to transmit a first frequency signal to the logic side of the isolation driver chip, so that the logic side shields a reset signal of the logic side according to the first frequency signal; and to select, when the desaturation latch signal is at a second level, to transmit a second frequency signal to the logic side, so that the logic side resumes responding to the reset signal, wherein the first frequency signal is a frequency signal corresponding to the desaturation phenomenon, and the second frequency signal is a frequency signal corresponding to the normal working state of the external power device.

[0008] Optionally, the desaturation detection module includes: a first inverter and a desaturation detection circuit, wherein the input end of the first inverter is coupled to the control electrode of the first pull-up transistor in the driver, the output end of the first inverter is coupled to the enable input end of the desaturation detection circuit, and the first pull-up transistor is a built-in transistor for generating a pull-up current for normally turning on the external power device; the desaturation detection circuit is configured to detect the drain-source voltage of the external power device, and determine whether the external power device has desaturated based on the drain-source voltage and the desaturation threshold voltage, and generate the desaturation indication signal.

[0009] Optionally, the desaturation enable signal generating module includes: a second inverter and a first trigger, wherein the input end of the second inverter is coupled to the output end of the latch, and the output end of the second inverter is coupled to the reset input end of the first trigger; the set input end of the first trigger is coupled to the desaturation indication signal, and the output end of the first trigger outputs the desaturation enable signal.

[0010] Optionally, the driver includes: a logic buffer unit and a transistor unit, wherein the logic buffer unit is configured to generate a drive signal for driving the transistor in the transistor unit based on the output signal of the latch and the desaturation enable signal; the transistor unit includes at least a first pull-up transistor and a first pull-down transistor, and is configured to drive the first pull-up transistor to generate a start signal for the external power tube or drive the first pull-down transistor to generate the soft shutdown signal according to the drive signal, and the transistor unit also outputs the soft shutdown feedback signal, and the first pull-down transistor is a built-in transistor for generating a pull-down current for soft-shutdown of the external power device.

[0011] Optionally, the soft shutdown detection module includes a soft shutdown detection unit and a second trigger, wherein the soft shutdown detection unit is configured to use the desaturation enable signal as the enable signal, and when the desaturation enable signal is at a valid level, compare the received soft shutdown feedback signal with a preset reference voltage, and generate the soft shutdown status indication signal according to the comparison result; the set input terminal of the second trigger is coupled to the desaturation enable signal, the reset input terminal of the second trigger is coupled to the soft shutdown status indication signal, the output terminal of the second trigger outputs the desaturation latch signal, and when the soft shutdown status indication signal is a level indicating that soft shutdown is not completed, the desaturation latch signal is controlled to be a first level, and when the soft shutdown status indication signal is a level indicating that soft shutdown is completed, the desaturation latch signal is controlled to be a second level.

[0012] Optionally, a first terminal of the latch is coupled to the input signal, a second terminal of the latch is coupled to the desaturation latch signal, and an output terminal of the latch is coupled to the driver and the desaturation enable signal generating module respectively.

[0013] Optionally, the first pull-up transistor is a P-type MOS transistor, and the first pull-down transistor is an N-type MOS transistor.

[0014] According to a second aspect of the present disclosure, an isolation driver chip is provided, comprising a logic side, an isolation channel, and a driver side, wherein the driver side comprises at least the soft shutdown control circuit in the isolation driver chip described in any one of the first aspects; the isolation channel is used to isolate the logic side from the driver side; the logic side is used to receive a first frequency signal or a second frequency signal sent by the driver side, and to shield a reset signal of the logic side according to the first frequency signal or to restore a response to the reset signal of the logic side according to the second frequency signal, and to control the state of an analog signal output port of the logic side according to the first frequency signal to remain at a high level during the reception of the first frequency signal.

[0015] According to a third aspect of the present disclosure, a soft shutdown control method in an isolated driver chip is provided, the method comprising: when an input signal received by a driver side of the isolated driver chip is at a high level, controlling an external power device to turn on through a driver on the driver side, and performing desaturation detection on the external power device to obtain a desaturation indication signal; if the desaturation indication signal is at a level indicating that desaturation has occurred, it is determined that desaturation has occurred in the external power device, and then controlling a desaturation enable signal to be at a valid level according to the desaturation indication signal, the desaturation enable signal being an enable signal for the driver and a soft shutdown detection module on the driver side; generating a soft shutdown signal for shutting off the external power device through the driver according to the desaturation enable signal, and controlling a desaturation latch signal to be at a first level; latching the input signal through a latch on the driver side according to the desaturation latch signal, and controlling a selector on the driver side to transmit a first frequency signal to a logic control module of the isolated driver chip according to the desaturation latch signal. side, so that the logic side shields the reset signal of the logic side according to the first frequency signal, the first frequency signal being a frequency signal corresponding to the desaturation phenomenon; detecting the soft shutdown state through the soft shutdown detection module according to the soft shutdown feedback signal fed back by the driver to obtain a soft shutdown state indication signal; if the soft shutdown state indication signal is at a level indicating that soft shutdown is not completed, it is determined that the external power device has not completed soft shutdown, and the desaturation latch signal is controlled to remain at a first level; when the soft shutdown state indication signal changes from a level indicating that soft shutdown is not completed to a level indicating that soft shutdown is completed, it is determined that the external power device has completed soft shutdown, and the desaturation latch signal is controlled to change to a second level; releasing the input signal through the latch according to the desaturation latch signal, and controlling the selector to transmit a second frequency signal to the logic side according to the desaturation latch signal, so that the logic side resumes responding to the reset signal, the second frequency signal being a frequency signal corresponding to the external power device in a normal working state.

[0016] Optionally, when the input signal received by the driving side changes from a high level to a low level, the desaturation enable signal is reset through the input signal of the driving side.

[0017] In the soft-shutdown control circuit and method in the isolated driver chip of the embodiment of the present disclosure, after detecting that an external power device has desaturated, a soft-shutdown signal is generated by the driver to control the external power device to perform a soft shutdown. When the soft-shutdown behavior is not completed, the soft-shutdown state is locked. That is, when the soft-shutdown behavior is not completed, the driver side will latch the received input signal and select the first frequency signal to transmit to the logic side to shield the reset signal on the logic side. After detecting that the soft-shutdown behavior is complete, the driver side releases the input signal and selects the second frequency signal to transmit to the logic side to restore the response to the reset signal and restore the normal operation of channel 1. This achieves closed-loop control after the occurrence of overcurrent / desaturation phenomena, solves the problem of the open-loop control method in the prior art that simply controls soft shutdown through a fixed time period, which may cause damage to the device due to not shutting down and then turning on again, and achieves better protection for the external power device. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly described below. It should be noted that the drawings described below only relate to some embodiments of the present disclosure and are not intended to limit the present disclosure.

[0019] Figure 1 Shows a framework diagram of an existing isolation driver chip;

[0020] Figure 2 A schematic block diagram of a soft shutdown control circuit in an isolation driver chip according to an embodiment of the present disclosure is shown;

[0021] Figure 3 A schematic circuit diagram of a soft shutdown control circuit in an isolation driver chip according to an embodiment of the present disclosure is shown;

[0022] Figure 4 A schematic block diagram of an isolation driver chip according to an embodiment of the present disclosure is shown;

[0023] Figure 5 A flow chart showing a soft shutdown control method in an isolation driver chip according to an embodiment of the present disclosure is shown;

[0024] Elements in the drawings are schematic and not drawn to scale. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative work also fall within the scope of protection of the present disclosure.

[0026] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the specification and the relevant art, and will not be interpreted in an idealized or overly formal manner unless otherwise explicitly defined herein. As used herein, a statement that two or more parts are "connected" or "coupled" together shall mean that the parts are joined together either directly or through one or more intermediate components.

[0027] In all embodiments of the present disclosure, terms such as “first” and “second” are used only to distinguish one component (or a part of a component) from another component (or another part of a component).

[0028] Figure 1 shows the framework of a conventional isolation driver chip 100, which includes a logic side 110, an isolation channel ISOLATION BARRIER, and a driver side 120. The isolation driver chip 100 has two channels: Channel 1, known as the data link, and Channel 2, known as the signal link. The data link transmits input signals (IN+, IN-) from the logic side 110 to the driver side 120. The driver side 120 generates switching signals (OUTH, OUTL) to control the on / off state of external power devices. The signal link, Channel 2, transmits analog signals from the driver side 120 (such as voltage, temperature, and other information, specifically corresponding to the AIN port signal) to the logic side 110 using a duty cycle mode (PWM gen), enabling specific signal monitoring of the driver side 120. Channel 2 is also time-division multiplexed to transmit driver side undervoltage or external power device overcurrent / desaturation status. To distinguish the three states, three signals with different frequencies are encoded into Channel 2. “0” represents undervoltage lockout (UVLO) on the driver side, “Carrier 1” represents desaturation (DESAT) on the driver side, and “Carrier 2” represents normal operation.

[0029] Figure 1In the example, when an external power device experiences overcurrent or desaturation, the corresponding implementation is as follows: When the driver side 120 detects the occurrence of DESAT (i.e., DESAT = 1), it shuts down the external power device using a soft shutdown (STO) method and generates a pulse of a fixed duration, Constant pulse. During this fixed duration, the multiplexer selects the Carrier 1 signal input to Channel 2. The logic side 110 then detects the occurrence of DESAT within a fixed duration, pulls down the nFLT (fault) port, and generates a blanking signal to shield the input of the nRST / EN port. It can be seen that regardless of whether the driver side 120 soft shutdown behavior is completed, it will resume Channel 2 after a fixed time, that is, transmit the frequency signal Carrier 2 representing normal operation. After the blanking time expires, the signal at the nRST / EN port is directly released. After receiving a valid reset signal at the nRST / EN port, the nFLT flag is cleared, and Channel 1 resumes normal operation. This can cause the external power device to not shut down and then turn on again, causing damage to the power device.

[0030] In order to solve the problem that the soft shutdown control method in the above-mentioned isolation driver chip 100 may cause external power devices to be turned on again without being turned off, thereby causing damage to the devices, a new soft shutdown control method in the isolation driver chip is proposed. The soft shutdown control method in the isolation driver chip of the embodiment of the present disclosure will lock the soft shutdown state until the soft shutdown behavior is not completed. The driver side will latch the received input signal, and the logic side will shield the reset signal of the logic side. After the soft shutdown behavior is completed, the driver side releases the input signal and the logic side releases the reset signal. In this way, closed-loop control is achieved after the overcurrent / desaturation phenomenon occurs. The soft shutdown control method in the isolation driver chip of the present disclosure is described in detail below.

[0031] Figure 2 The schematic block diagram of a soft-off control circuit 200 in an isolation driver chip according to an embodiment of the present disclosure is shown. The soft-off control circuit 200 in the embodiment of the present disclosure is a circuit applied in an isolation driver chip, wherein the isolation driver chip is connected to the isolation driver chip. Figure 1 The isolated driver chip shown is also used to drive the external power device, and when the external power device is desaturated, the soft shutdown control circuit performs soft shutdown control on the external power device (it should be noted here that the embodiment of the present disclosure is mainly aimed at the soft shutdown control after the desaturation phenomenon, so the control of undervoltage and temperature is not described). Figure 2 As shown, the soft shutdown control circuit 200 in the isolation driver chip includes: a desaturation detection module 210, a desaturation enable signal generating module 220, a driver 230, a soft shutdown detection module 240, a latch 250, and a multiplexer 260.

[0032] The desaturation detection module 210 is coupled to the driver 230 and the desaturation enable signal generation module 220, respectively. After the external power device is turned on, the module is configured to perform desaturation detection on the external power device and generate a desaturation indication signal Desat indicating whether desaturation has occurred. Desaturation can only occur when the power device is turned on, so the desaturation detection module must be configured to activate after the external power device is turned on. Figure 1 The OUTHPG signal is a gate control signal of a pull-up transistor inside the driver 230. When OUTHPG is low, OUTH can be enabled, thereby controlling the start-up of the external power device. Therefore, the startup of the desaturation detection module 210 can be controlled according to OUTHPG. The detection principle of the desaturation detection module 210 is the same as the principle of desaturation detection of existing power devices, that is, it is achieved by detecting whether the voltage (drain-source voltage of the external power device) exceeds the threshold. If it exceeds the threshold, it is determined that desaturation occurs, otherwise it does not occur. In the embodiment of the present disclosure, the desaturation indication signal Desat is used to indicate whether desaturation occurs. Specifically, if Desat=1 (high level), it indicates that desaturation occurs, and Desat=0 (low level), it indicates that desaturation does not occur. In addition, in actual applications, the desaturation detection module 210 is implemented as follows. Figure 1 The DESAT port is shown coupled to an external power device.

[0033] The desaturation enable signal generating module 220 is coupled to the desaturation detection module 210, the driver 230, the soft-shutdown detection module 240, and the latch 250, respectively. The module is configured to generate a desaturation enable signal DesatEN based on the desaturation indication signal Desat and the output signal A of the latch 250. When the desaturation indication signal Desat is at a level indicating desaturation, the module controls the desaturation enable signal DesatEN to be at an active level. The desaturation enable signal DesatEN serves as an enable signal for the driver 230 and the soft-shutdown detection module 240.

[0034] The driver 230 is also coupled to the soft shutdown detection module 240 and is configured to receive the output signal A of the latch 250 and generate a soft shutdown signal OUTL for shutting down the external power device and a soft shutdown feedback signal softFB according to the output signal A and the desaturation enable signal DesatEN. Specifically, when the desaturation enable signal DesatEN is valid (high), soft shutdown (STO) is performed, that is, the soft shutdown signal OUTL is generated by the pull-down transistor corresponding to the soft shutdown built into the driver 230. The OUTL signal is Figure 1OUTL port in the latch 250 is coupled. In actual applications, the driver can also generate a normal shutdown signal. In the normal shutdown case, the normal shutdown signal is also represented by OUTL. Since they are both shutdown signals, the difference is that the values ​​of the corresponding OUTL signals are different for different types of shutdown signals. When the desaturation enable signal DesatEN is invalid (low level), the driver 230 generates signals (OUTH, OUTL) for controlling the switching of the external power device based on the output signal A of the latch 250. In addition, the driver 230 in the embodiment of the present disclosure can also generate a feedback signal that can be used to reflect the execution status of the soft shutdown, namely the soft shutdown feedback signal softFB, which is sent to the soft shutdown detection module 240.

[0035] The soft-shutdown detection module 240 is further coupled to the multiplexer 260 and configured to detect the soft-shutdown state based on the desaturation enable signal DesatEN and the soft-shutdown feedback signal softFB, and to generate a soft-shutdown state indication signal softDone indicating whether soft-shutdown is complete. Specifically, when softDone = 1 (high level), soft-shutdown is complete; when softDone = 0 (low level), soft-shutdown is incomplete. After obtaining the soft-shutdown state indication signal softDone, the desaturation latch signal Desatlatch is controlled based on the soft-shutdown state indication signal softDone. Specifically, when the soft-shutdown state indication signal softDone is at a level (low level) indicating that soft-shutdown is incomplete, i.e., soft-shutdown is incomplete, the desaturation latch signal Desatlatch is controlled to a first level. When the soft-shutdown state indication signal softDone is at a level (high level) indicating that soft-shutdown is complete, i.e., soft-shutdown is complete, the desaturation latch signal Desatlatch is controlled to a second level. Specifically, the first level may be a high level, and the second level may be a low level.

[0036] The latch 250 is configured to receive the input signal IN1 of the driving side of the isolation driver chip, and latch or release the input signal IN1 according to the desaturation latch signal Desatlatch, and output it to the driver 230, and latch the input signal IN1 when the desaturation latch signal Desatlatch is at the first level, and release the input signal IN1 when the desaturation latch signal Desatlatch is at the second level. It can be seen that the latch 250 in the embodiment of the present disclosure is to latch the input signal IN1 received by the driving side during the soft shutdown period. Even if the driving side receives a signal to turn on the external power device during the period when the soft shutdown is not completed, it will not be transmitted to the driver 230, thereby avoiding the situation where the external power device is reopened during the soft shutdown period. In addition, it should be noted that in actual applications, the signal IN1 received by the latch 250 is not the signal directly received by the driving side. The signal directly received by the driving side needs to be demodulated by the receiver (digitalisolar receiver) to obtain IN1. IN1 corresponds to Figure 1 RX1_OUT in the figure. A first terminal of latch 250 is coupled to input signal IN1, a second terminal of latch 250 is coupled to desaturation latch signal Desatlatch, and output terminals of latch 250 are respectively coupled to driver 230 and desaturation enable signal generating module 220. Latch 250 can be specifically an RS latch, a D latch, a JK latch, etc., and the specific form and type are not limited, as long as it can achieve the function of latching input signal IN1 when desaturation latch signal Desatlatch is at a high level and releasing input signal IN1 when desaturation latch signal Desatlatch is at a low level.

[0037] The multiplexer 260 includes at least two data input terminals for receiving a first frequency signal carrier 1 and a second frequency signal carrier 2. The output F is carrier 1 or carrier 2. The multiplexer 260 is configured to select the first frequency signal carrier 1 to be transmitted to the logic side of the isolation driver chip when the desaturation latch signal Desatlatch is at a first level, so that the logic side shields the reset signal of the logic side according to the first frequency signal carrier 1; and to select the second frequency signal carrier 2 to be transmitted to the logic side when the desaturation latch signal Desatlatch is at a second level, so that the logic side recovers its response to the reset signal. The first frequency signal carrier 1 is a frequency signal corresponding to the desaturation phenomenon, typically a high-frequency signal. The second frequency signal carrier 2 is a frequency signal corresponding to the normal working state of the external power device, typically a low-frequency signal. In this embodiment, the desaturation latch signal Desatlatch is used as the control signal of the multiplexer 260 (i.e., coupled to the sel terminal). Compared with the prior art, the desaturation latch signal Desatlatch is always kept at the first level during the entire soft-off period. That is, the time of selecting the first frequency signal carrier 1 is determined by the soft-off state, rather than by the constant pulse time. Therefore, it can be effectively ensured that the reset signal of the logic side (corresponding to the reset signal) is shielded during the soft-off period. Figure 1 This avoids the situation in the prior art where soft shutdown is not completed and the nRST / EN port signal is responded to to restore channel 1 to normal operation.

[0038] From the above description, it can be seen that in the soft-off control circuit 200 in the isolated driver chip of the present embodiment, after detecting desaturation of the external power device, the driver generates a soft-off signal to control the external power device to perform soft shutdown. When the soft-off behavior is not completed, the soft-off state is locked regardless of whether the blanking time has expired. That is, when the soft-off behavior is not completed, the driver side will continue to latch the received input signal and select the first frequency signal to transmit to the logic side to shield the reset signal on the logic side. After detecting that the soft-off behavior is complete, the driver side releases the input signal and selects the second frequency signal to transmit to the logic side to resume response to the reset signal and restore normal operation of channel 1. This achieves closed-loop control after overcurrent / desaturation occurs, solving the problem of external power devices not being turned off and then turned on again, which may cause device damage, caused by the open-loop control method in the prior art that simply controls soft shutdown through a fixed time period. This provides better protection for the external power devices.

[0039] Further, such as Figure 3 As shown, the desaturation detection module 210 includes a first inverter NOT1 and a desaturation detection circuit 211. The input of the first inverter NOT1 is coupled to the control electrode OUTHPG of a first pull-up transistor in the driver 230, and the output of the first inverter NOT1 is coupled to the enable input of the desaturation detection circuit 211. The first pull-up transistor is a built-in transistor for generating a pull-up current to normally enable an external power device. Specifically, the first pull-up transistor is a P-type MOS transistor. When the first pull-up transistor is turned on, the control electrode OUTHPG of the first pull-up transistor is at a low level. After passing through the first inverter NOT1, a high level signal is generated, thereby initiating detection by the desaturation detection circuit 211. Figure 3 The desaturation detection circuit 211 is configured to detect the drain-source voltage VDS of the external power device, determine whether desaturation has occurred in the external power device based on the drain-source voltage VDS and the desaturation threshold voltage, and generate a desaturation indication signal Desat. Specifically, when the drain-source voltage VDS exceeds the desaturation threshold voltage, the desaturation indication signal Desat is at a level indicating the occurrence of desaturation (e.g., a high level), indicating that desaturation has occurred. When the drain-source voltage VDS does not exceed the desaturation threshold voltage, the desaturation indication signal Desat is at a level indicating the absence of desaturation (e.g., a low level), indicating that desaturation has not occurred. The desaturation detection circuit 211 in this embodiment shares the same principle and structure as the desaturation detection circuit in existing isolated drivers (e.g., the UCC21750-Q1 isolated driver 230).

[0040] Further, such as Figure 3 As shown, the desaturation enable signal generating module 220 includes: a second inverter NOT2 and a first flip-flop T1, wherein the input terminal of the second inverter NOT2 is coupled to the output terminal A of the latch 250, and the output terminal of the second inverter NOT2 is coupled to the reset input terminal R of the first flip-flop T1; the set input terminal S of the first flip-flop T1 is coupled to the desaturation indication signal Desat, and the output terminal Q of the first flip-flop T1 outputs the desaturation enable signal DesatEN.

[0041] Further, such as Figure 3As shown, the driver 230 includes: a logic buffer unit 231 and a transistor unit 232, wherein the logic buffer unit 231 is configured to generate a driving signal (including OUTHPG and SOFTNG) for driving the transistor in the transistor unit 232 according to the output signal A of the latch 250 and the desaturation enable signal DesatEN; the transistor unit 232 includes a first pull-up transistor and a first pull-down transistor, and is configured to drive the first pull-up transistor to generate an external power tube start signal OUTH or drive the first pull-down transistor to generate a soft shutdown signal OUTL according to the driving signal (OUTHPG (driving the first pull-up transistor), SOFTNG (driving the first pull-down transistor)). The transistor unit 232 also outputs a soft shutdown feedback signal softFB, and the first pull-down transistor is a built-in transistor for generating a pull-down current for soft-shutdown of an external power device. The logic buffer unit 231 can generate a driving current for all transistors in the driving transistor unit 232. The current is usually a small current. After the transistors in the transistor unit 232 are driven by the small current, a large current is generated to drive external power devices (such as insulated gate bipolar transistors, IGBTs). Driver 230 operates as follows: If signal A output by latch 250 is high and desaturation enable signal DesatEN is inactive (e.g., low), driver 230 generates a low current signal (corresponding to signal OUTHPG) to drive the first pull-up transistor. This signal generates a higher pull-up current to enable the external power device. When desaturation enable signal DesatEN becomes active (e.g., high), driver 230 generates a low current signal (corresponding to signal SOFTNG) to drive the first pull-down transistor. This signal generates a higher pull-down current to disable the external power device via soft shutdown. After soft shutdown is executed, driver 230 also outputs a voltage feedback signal, softFB, to provide feedback on the soft shutdown execution. Specifically, this feedback signal is the voltage of a node in transistor unit 232. The specific node is not critical, as long as it can reflect the soft shutdown execution. In addition, the embodiments of the present disclosure are mainly aimed at soft shutdown control after desaturation, so only the devices and control methods involved in soft shutdown are described. In actual applications, the driver 230 will also include circuit structures and devices corresponding to control methods such as normal shutdown and Miller shutdown, just like the existing ones. In addition, it should be noted that all pull-up transistors (including the first pull-up transistor) in the transistor unit 232 can be P-type MOS tubes, and all pull-down transistors (including the first pull-down transistor) can be N-type MOS tubes.

[0042] Further, such as Figure 3As shown, the soft shutdown detection module 240 includes a soft shutdown detection unit 241 and a second trigger T2, wherein the soft shutdown detection unit 241 is configured to take the desaturation enable signal DesatEN as an enable signal, and when the desaturation enable signal DesatEN is at an effective level, compare the received soft shutdown feedback signal softFB with a preset reference voltage, and generate a soft shutdown state indication signal softDone according to the comparison result; further, when the voltage of the soft shutdown feedback signal softFB is greater than the preset reference voltage, it indicates that the soft shutdown is completed, that is, the soft shutdown state indication signal softDone is a level indicating that soft shutdown is complete (e.g., a high level). When the voltage of the soft-shutdown feedback signal softFB is not greater than a preset reference voltage, it indicates that soft shutdown is not complete, i.e., the soft-shutdown status indication signal softDone is a level indicating that soft shutdown is not complete (e.g., a low level). The set input S of the second flip-flop T2 is coupled to the desaturation enable signal DesatEN, the reset input R of the second flip-flop T2 is coupled to the soft-shutdown status indication signal softDone, and the output Q of the second flip-flop T2 outputs the desaturation latch signal Desatlatch. Furthermore, when the desaturation enable signal DesatEN is at an active level (e.g., a high level) but the soft-shutdown status indication signal softDone is at a level indicating that soft shutdown is not complete (e.g., a low level), the desaturation latch signal Desatlatch is at a first level until the soft-shutdown status indication signal softDone is at a level indicating that soft shutdown is complete (e.g., a high level), at which point the desaturation latch signal Desatlatch changes to a second level. Furthermore, the soft-off detection unit 241 may be implemented by a comparator circuit, which compares the soft-off feedback signal softFB with a preset reference voltage and outputs a comparison result.

[0043] The following combination Figure 3The working principle of the soft-off control circuit 200 in the isolated driver chip in the embodiment of the present disclosure is explained more clearly: the initial state of Desatlatch is 0 (low level), the latch 250 does not latch IN1, and IN1 can normally control the driver 230 to generate OUTHPG when IN1 is high level, as in the prior art, and further control the first pull-up transistor in the transistor unit 232 to turn on and output OUTH to turn on the external power device. At the same time, OUTHPG (low level at this time) passes through the first inverter NOT1 (high level) as an enable signal of the desaturation detection circuit 211, and starts to detect the desaturation phenomenon of the external power tube device. When desaturation occurs, Desat=1 (high level). At this time, the output A of the latch 250 is also 1. After passing through the second inverter NOT2, the reset input R of the first flip-flop T1 is 0, so DesatEN is set to 1. DesatEN enables the soft shutdown detection unit 241, causing it to start monitoring whether the soft shutdown is completed through the softFB signal fed back by the driver 230. When it is not completed, softDone is 0, so the reset input R of the second flip-flop T2 is also 0. The set input S of the second flip-flop T2 is coupled to DesatEN and is therefore 1. Therefore, the Desatlatch output by the second flip-flop T2 is set to 1; when Desatlatch is 1, the latch 250 starts to shield the IN1 signal and controls the multiplexer 260 to select the carrier1 output to the logic side (through Figure 1 The logic side will reset the terminal ( Figure 1 Until the soft shutdown is completed, softDone is 1, Desatlatch is reset to 0, IN1 is released, and multiplexer 260 selects carrier2 to output to the logic side, which resets the reset terminal ( Figure 1 The nRST / EN port in the isolation driver chip is released, and the isolation driver chip resumes normal operation until IN1 is 0, the reset input terminal R of T1 is 1, and the DesatEN signal is also reset (0).

[0044] From the above working principle, it can be seen that the soft shutdown control scheme in the embodiment of the present disclosure latches IN1 after desaturation occurs, and responds to IN1 after detecting that the soft shutdown has been completed, effectively avoiding the restart behavior when the soft shutdown is not completed.

[0045] The embodiment of the present disclosure also provides an isolation driver chip 300, such as Figure 4 As shown, the isolation driver chip 300 includes a logic side 310, an isolation channel ISOLATION BARRIER, and a driver side 320.

[0046] Among them, the driving side 320 at least includes the soft shutdown control circuit 200 in the isolation driver chip in the aforementioned embodiment. The structure and principle of each module in the soft shutdown control circuit 200 can refer to the description in the aforementioned embodiment and will not be repeated here. The driving side 320 also includes a circuit for controlling the normal switching and Miller shutdown of the external power device, as well as a circuit for undervoltage monitoring and protection of the driving side 320, and monitoring the temperature of the external power device. There are also transmitters and receivers for modulation and demodulation. The difference between the driving side 320 in the embodiment of the present disclosure and the driving side 120 in the isolation driver chip in the prior art lies in the improvement of the soft shutdown control circuit. In order to avoid unnecessary details that obscure the focus of the present disclosure, other parts are not shown.

[0047] The isolation channel ISOLATION BARRIER is used to isolate the logic side 310 from the driving side 320 . The isolation channel ISOLATION BARRIER has the same structure as the existing isolation channel ISOLATION BARRIER and can be implemented by capacitors.

[0048] The logic side 310 is used to receive the first frequency signal carrier1 or the second frequency signal carrier2 sent by the driving side 320, and shield or restore the reset signal (signal corresponding to the nRST / EN port) of the response logic side 310 according to the first frequency signal carrier1 or the second frequency signal carrier2, and control the state of the analog signal output port (APWM port) of the logic side 310 according to the first frequency signal carrier1 to maintain a high level during the period of receiving the first frequency signal carrier1. Specifically, Figure 4 As shown, the logic side 310 receives the first frequency signal carrier1 and the second frequency signal carrier2 modulated by the transmitter of the driving side 320 through the receiver of the logic side 310 for demodulation. After demodulation, they are filtered (carrier1 filter / carrier2 filter) and decoded (Fault decoder / Apwm decoder) and finally output to the corresponding port (nFLT / APWM). Moreover, after filtering, carrier1 will control the Apwm decoder to affect the output of APWM so that it remains at a high level during the transmission of carrier1. In addition, FLT_logic is related to nFLT, and the signal of FLT_logic can act on the Input logic to shield or respond to the nRST / EN port. Compare Figure 1 and Figure 4 In the logic side, it can be seen that the logic side 310 of the embodiment of the present disclosure is different from that in the prior art ( Figure 1The difference between the two is that, in the prior art, a fixed time pulse Constant pulse is generated after desaturation occurs, and the driver side 110 transmits carrier 1 only within the fixed time period. However, if the soft shutdown is not completed or the fault is not decoded within the fixed time period, the transmission of carrier 2 will be resumed. However, in this embodiment, carrier 1 is continuously sent during the execution of soft shutdown, and the logic side 310 can continuously receive carrier 1 during the execution of soft shutdown, so as to avoid resuming the transmission of carrier 2 without completing soft shutdown. In addition, in order to further improve safety, the APWM port is also controlled to be always high level (1) during this period according to carrier 1, because when the external controller receives that the APWM port output of the isolation driver 230 chip is always "1", but the power flag RDY is "1" (power is normal) and the nFLT port is also "1" (the fault decoder does not decode the fault (specifically the desaturation fault in this embodiment)), the controller can still determine that an abnormal situation has occurred based on the APWM port output being always "1", and promptly shut down the external power device and issue an abnormal alarm.

[0049] From the above description, it can be seen that the isolated driver chip 300 of the disclosed embodiment can latch IN1 after desaturation occurs, and then respond to IN1 after detecting that soft shutdown has completed. This effectively prevents restarting if soft shutdown is not completed. Furthermore, when a fault cannot be interpreted, the APWM port output can be used to determine an abnormality, further improving the safety of the external power transistor.

[0050] The present disclosure also provides a soft shutdown control method in an isolation driver chip applied to the soft shutdown control circuit in the isolation driver chip in the aforementioned embodiment, such as Figure 5The flowchart of the soft shutdown control method is shown, and the method includes S401-S408: S401. When the input signal received by the driving side of the isolation driver chip is high, the external power device is controlled to be turned on through the driver on the driving side, and desaturation detection is performed on the external power device to obtain a desaturation indication signal; S402. If the desaturation indication signal is at a level indicating that desaturation has occurred, it is determined that desaturation has occurred in the external power device, and then the desaturation enable signal is controlled to be a valid level according to the desaturation indication signal; wherein the desaturation enable signal is an enable signal for the driver and the soft shutdown detection module on the driver side; S403. According to the desaturation enable signal, a soft shutdown signal for shutting off the external power device is generated by the driver, and a desaturation latch signal is controlled to be a first level; S404. According to the desaturation latch signal, the input signal is latched by the latch on the driver side, and according to the desaturation latch signal, the selector on the driver side is controlled to transmit the first frequency signal to the logic side of the isolation driver chip; so that the logic side shields the reset signal of the logic side according to the first frequency signal, The first frequency signal is a frequency signal corresponding to the desaturation phenomenon; S405. Based on the soft-shutdown feedback signal fed back by the driver, a soft-shutdown detection module detects the soft-shutdown state to obtain a soft-shutdown state indication signal; S406. If the soft-shutdown state indication signal is at a level indicating that soft-shutdown is not completed, it is determined that the external power device has not completed soft-shutdown, and the desaturation latch signal is controlled to remain at the first level; when the desaturation latch signal remains at the first level, the input signal is still latched, and the first frequency signal is transmitted to the logic side of the isolation driver chip; S407. When the soft-shutdown state indication signal changes from a level indicating that soft-shutdown is not completed to a level indicating that soft-shutdown is completed, it is determined that the external power device has completed soft-shutdown, and the desaturation latch signal is controlled to change to a second level; S408. Based on the desaturation latch signal, the input signal is released through the latch, and the selector is controlled to transmit the second frequency signal to the logic side according to the desaturation latch signal, so that the logic side resumes responding to the reset signal, wherein the second frequency signal is a frequency signal corresponding to the external power device in normal working state.

[0051] Furthermore, after the input signal is released, when the input signal received by the driving side changes from a high level to a low level, the desaturation enable signal is reset through the input signal of the driving side.

[0052] Furthermore, after the logic side receives the first frequency signal, in addition to shielding the reset signal of the logic side according to the first frequency signal, it also includes controlling the state of the analog signal output APWM port of the logic side according to the first frequency signal to remain at a high level during the period of receiving the first frequency signal, so that when the fault cannot be translated, it is determined that there is an abnormal situation based on the APWM port output, thereby further improving the safety of the external power tube.

[0053] The specific implementation of each step in the embodiment of the present disclosure can refer to the corresponding description in the aforementioned embodiment, which will not be repeated here. In addition, the numbering of the steps in the embodiment of the present disclosure does not limit the actual execution order, and other execution orders can also be used, which can be adaptively adjusted according to actual needs.

[0054] From the above description, we can see that the soft-shutdown control method in the isolated driver chip of the disclosed embodiment can latch IN1 after desaturation occurs, and only respond to IN1 after detecting that soft shutdown has completed. This effectively avoids restarting if soft shutdown is not completed. Furthermore, when a fault cannot be interpreted, the APWM port output can be used to determine an abnormality, further improving the safety of the external power transistor.

[0055] In the above embodiments of the present disclosure, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0056] In summary, the soft-shutdown control method in the isolated driver chip in the embodiment of the present disclosure will lock the soft-shutdown state when the soft-shutdown behavior is not completed. After the soft-shutdown behavior is completed, the driver side releases the input signal and the logic side releases the reset signal. This realizes closed-loop control after overcurrent / desaturation occurs; in addition, it also improves the safety of the external power tube.

[0057] Unless the context clearly indicates otherwise, as used herein and in the appended claims, the singular includes the plural, and vice versa. Thus, when referring to the singular, the plural of the corresponding term is generally included. Similarly, the words "include" and "comprising" are to be interpreted as inclusive rather than exclusive. Likewise, the terms "include" and "or" should be interpreted as inclusive unless such interpretation is expressly prohibited herein. Where the term "example" is used herein, particularly when it follows a group of terms, "example" is merely exemplary and illustrative and should not be considered exclusive or comprehensive.

[0058] Further aspects and scope of adaptability become apparent from the description provided herein. It should be understood that various aspects of the present disclosure can be implemented individually or in combination with one or more other aspects. It should also be understood that the description and specific embodiments herein are intended to be illustrative only and are not intended to limit the scope of the present disclosure.

[0059] Several embodiments of the present disclosure have been described in detail above, but it is obvious that those skilled in the art can make various modifications and variations to the embodiments of the present disclosure without departing from the spirit and scope of the present disclosure. The scope of protection of the present disclosure is defined by the appended claims.

Claims

1. A soft shutdown control circuit in an isolation driver chip, wherein the isolation driver chip is used to drive an external power device. When the external power device is desaturated, the soft shutdown control circuit performs soft shutdown control on the external power device, characterized in that: The soft shutdown control circuit includes: a desaturation detection module, a desaturation enable signal generation module, a driver, a soft shutdown detection module, a latch, and a multiplexer. The desaturation detection module is configured to perform desaturation detection on the external power device after the external power device is turned on, and obtain a desaturation indication signal for indicating whether desaturation occurs; The desaturation enable signal generating module is configured to generate the desaturation enable signal according to the desaturation indication signal and the output signal of the latch, and control the desaturation enable signal to be at a valid level when the desaturation indication signal is at a level indicating that desaturation has occurred; The driver is configured to receive the output signal of the latch and generate a soft shutdown feedback signal and a soft shutdown signal for shutting down the external power device according to the output signal and the desaturation enable signal; The soft shutdown detection module is configured to detect a soft shutdown state according to the desaturation enable signal and the soft shutdown feedback signal, obtain a soft shutdown state indication signal indicating whether the soft shutdown is completed, and control a desaturation latch signal according to the soft shutdown state indication signal; The latch is configured to receive an input signal from the driving side of the isolation driver chip, latch or release the input signal according to the desaturation latch signal, and output the signal to the driver, and latch the input signal when the desaturation latch signal is at a first level, and release the input signal when the desaturation latch signal is at a second level; The multiplexer is configured to select, when the desaturation latch signal is at a first level, to transmit a first frequency signal to the logic side of the isolation driver chip, so that the logic side shields a reset signal of the logic side according to the first frequency signal; and to select, when the desaturation latch signal is at a second level, to transmit a second frequency signal to the logic side, so that the logic side resumes responding to the reset signal, wherein the first frequency signal is a frequency signal corresponding to the desaturation phenomenon, and the second frequency signal is a frequency signal corresponding to the normal working state of the external power device.

2. The soft shutdown control circuit in the isolation driver chip according to claim 1, characterized in that: The desaturation detection module includes: a first inverter, a desaturation detection circuit, The input terminal of the first inverter is coupled to the control terminal of the first pull-up transistor in the driver, the output terminal of the first inverter is coupled to the enable input terminal of the desaturation detection circuit, and the first pull-up transistor is a built-in transistor for generating a pull-up current for normally turning on the external power device; The desaturation detection circuit is configured to detect the drain-source voltage of the external power device, determine whether the external power device has desaturated according to the drain-source voltage and a desaturation threshold voltage, and generate the desaturation indication signal.

3. The soft shutdown control circuit in the isolation driver chip according to claim 1, characterized in that: The desaturation enable signal generating module includes: a second inverter, a first trigger, The input terminal of the second inverter is coupled to the output terminal of the latch, and the output terminal of the second inverter is coupled to the reset input terminal of the first trigger; A set input terminal of the first flip-flop is coupled to the desaturation indication signal, and an output terminal of the first flip-flop outputs the desaturation enable signal.

4. The soft shutdown control circuit in the isolation driver chip according to claim 2, characterized in that: The driver includes: a logic buffer unit, a transistor unit, The logic buffer unit is configured to generate a driving signal for driving the transistor in the transistor unit according to the output signal of the latch and the desaturation enable signal; The transistor unit includes at least a first pull-up transistor and a first pull-down transistor, and is configured to drive the first pull-up transistor to generate a start signal for the external power device or drive the first pull-down transistor to generate the soft shutdown signal according to the drive signal. The transistor unit also outputs the soft shutdown feedback signal. The first pull-down transistor is a built-in transistor for generating a pull-down current for softly shutting down the external power device.

5. The soft shutdown control circuit in the isolation driver chip according to claim 4, characterized in that: The soft shutdown detection module includes a soft shutdown detection unit and a second trigger. The soft shutdown detection unit is configured to use the desaturation enable signal as an enable signal, and when the desaturation enable signal is at a valid level, compare the received soft shutdown feedback signal with a preset reference voltage, and generate the soft shutdown state indication signal according to the comparison result; The set input terminal of the second flip-flop is coupled to the desaturation enable signal, the reset input terminal of the second flip-flop is coupled to the soft-shutdown state indication signal, and the output terminal of the second flip-flop outputs the desaturation latch signal. When the soft-shutdown state indication signal is at a level indicating that soft shutdown is not completed, the desaturation latch signal is controlled to be a first level; when the soft-shutdown state indication signal is at a level indicating that soft shutdown is completed, the desaturation latch signal is controlled to be a second level.

6. The soft shutdown control circuit in the isolation driver chip according to claim 1, characterized in that: A first terminal of the latch is coupled to the input signal, a second terminal of the latch is coupled to the desaturation latch signal, and an output terminal of the latch is coupled to the driver and the desaturation enable signal generating module respectively.

7. The soft shutdown control circuit in the isolation driver chip according to claim 4, characterized in that: The first pull-up transistor is a P-type MOS transistor, and the first pull-down transistor is an N-type MOS transistor.

8. An isolation driver chip, comprising a logic side, an isolation channel, and a driver side, characterized in that: The driving side comprises at least the soft shutdown control circuit in the isolation driving chip according to any one of claims 1 to 7; The isolation channel is used to isolate the logic side from the drive side; The logic side is used to receive the first frequency signal or the second frequency signal sent by the driving side, and to shield the reset signal of the logic side according to the first frequency signal or to restore the response to the reset signal of the logic side according to the second frequency signal, and to control the state of the analog signal output port of the logic side according to the first frequency signal to remain at a high level during the reception of the first frequency signal.

9. A soft shutdown control method in an isolation driver chip, characterized in that: The method comprises: When the input signal received by the driving side of the isolation driver chip is at a high level, the driver on the driving side controls the external power device to turn on, and performs desaturation detection on the external power device to obtain a desaturation indication signal; If the desaturation indication signal is at a level indicating desaturation, it is determined that desaturation has occurred in the external power device, and a desaturation enable signal is controlled to be at a valid level according to the desaturation indication signal, wherein the desaturation enable signal is an enable signal for the driver and the soft shutdown detection module on the driving side; generating, by the driver, a soft-off signal for shutting down the external power device according to the desaturation enable signal, and controlling the desaturation latch signal to be at a first level; latching the input signal through the latch on the driver side according to the desaturation latch signal, and controlling the selector on the driver side to transmit a first frequency signal to the logic side of the isolation driver chip according to the desaturation latch signal, so that the logic side shields the reset signal of the logic side according to the first frequency signal, wherein the first frequency signal is a frequency signal corresponding to the desaturation phenomenon; Detecting a soft shutdown state through the soft shutdown detection module according to the soft shutdown feedback signal fed back by the driver to obtain a soft shutdown state indication signal; If the soft-shutdown state indication signal is at a level indicating that the soft-shutdown is not completed, it is determined that the external power device has not completed the soft-shutdown, and the desaturation latch signal is controlled to remain at the first level; When the soft-shutdown state indication signal changes from a level indicating that soft-shutdown is not completed to a level indicating that soft-shutdown is completed, it is determined that the external power device has completed soft-shutdown, and the desaturation latch signal is controlled to change to a second level; The input signal is released through the latch according to the desaturation latch signal, and the selector is controlled according to the desaturation latch signal to transmit a second frequency signal to the logic side so that the logic side recovers its response to the reset signal, wherein the second frequency signal is a frequency signal corresponding to the external power device in a normal working state.

10. The soft shutdown control method in the isolation driver chip according to claim 9, characterized in that: When the input signal received by the driving side changes from a high level to a low level, the desaturation enable signal is reset through the input signal of the driving side.

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