CN216751189U - Clamp protection circuit and vehicle-mounted electronic equipment - Google Patents
Clamp protection circuit and vehicle-mounted electronic equipment Download PDFInfo
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- CN216751189U CN216751189U CN202220354582.3U CN202220354582U CN216751189U CN 216751189 U CN216751189 U CN 216751189U CN 202220354582 U CN202220354582 U CN 202220354582U CN 216751189 U CN216751189 U CN 216751189U
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Abstract
The utility model relates to a clamp protection circuit for a vehicle MCU and a vehicle-mounted electronic device. The clamp protection circuit includes: an input terminal connected to a power switch; a clamp protection terminal connected to one or more pins of a vehicle MCU; a power supply terminal connected to an external clamp power supply; a first power transistor and a second power transistor configured to be selectively turned on or off based on a status signal of the power switch, respectively, to cause the clamp protection circuit to initiate different clamp protection modes. The clamp protection circuit according to the present invention has advantages in that: two different clamping modes can be realized only by combining simple power tubes, and fewer circuit components are adopted, so that the cost is lower; in addition, the clamping protection circuit can bear larger current and can be expanded into a multi-path I/O pin protection circuit.
Description
Technical Field
The utility model relates to the field of circuit protection, in particular to a clamping protection circuit and vehicle-mounted electronic equipment, and particularly relates to the clamping protection circuit for a vehicle MCU and the vehicle-mounted electronic equipment comprising the clamping protection circuit.
Background
An MCU (Microcontroller Unit: micro control Unit) is a core component of an in-vehicle electronic device, and generally includes a plurality of input/output interfaces (also referred to as "I/O pins" or "I/O interfaces") for connecting to external devices.
Under normal circumstances, the MCU must rely on power drawn from the MCU power supply to maintain its own operation. However, we have observed that even if the MCU is powered off, it is possible that the MCU may not be actually powered off, but rather that an automatic restart may occur intermittently or power consumption may continue to occur. As shown in fig. 1, when the MCU power is turned off by means of a power switch (which may be, for example, a key switch of a vehicle), since an I/O pin of the MCU is connected to an external device, power of the external device may still flow into a clamping diode inside the MCU via the I/O pin and then into the internal power of the MCU, thereby supplying energy to the MCU. In this case, the MCU is not actually turned off, but continues to generate power consumption in an abnormal operating state, for example, data is intermittently transmitted through the CAN/Ethernet/UART bus, the LED indicator lights are hidden and lighted, etc.
In this abnormal operating mode, there are many risks. For example, when the current flowing into the MCU from the I/O pin is too large, the MCU cannot be effectively turned off, which may cause the vehicle system to fail to enter a low power mode; when the current flowing from the external equipment exceeds the input limit of the I/O pin, electronic components such as a clamping diode and the like in the MCU can be directly burnt, so that the MCU fails. In addition, the data transmitted by the MCU through the bus at abnormal start-up is often erroneous, which may further affect the normal operation of the external device connected to the MCU.
In order to avoid damage to the I/O pin of the MCU and internal devices thereof caused by an input signal from an external device, in a conventional solution, a mode of diode pull-up clamping power supply is mostly used to implement clamp protection, however, this mode cannot prevent an interference signal of the external device from flowing into the MCU through the I/O pin when the device is in a sleep state, and thus cannot solve the problem of abnormal start of the MCU.
In other conventional solutions, it is contemplated to provide an electronic switch on each I/O pin to disable external current flow into the MCU when the device is asleep. However, this solution requires a separate electronic switch on each I/O pin, which, especially in the case of a multi-pin MCU, results in a bulky circuit board, excessive power consumption, and high cost.
SUMMERY OF THE UTILITY MODEL
The utility model provides a clamping protection circuit for a vehicle MCU (microprogrammed control Unit), which can execute different overvoltage clamping protection measures on an I/O (input/output) pin of the MCU with fewer circuit components and lower manufacturing cost aiming at different working states (switching on or off an external power supply) of the vehicle-mounted electronic equipment, particularly the MCU of the vehicle-mounted electronic equipment.
Specifically, according to a first aspect of the present invention, there is provided a clamp protection circuit for a vehicle MCU, the clamp protection circuit comprising:
an input terminal connected to a power switch;
the clamp protection end is connected to one or more pins of the vehicle MCU;
a power supply terminal connected to an external clamping power supply;
a first power transistor and a second power transistor, wherein the first power transistor and the second power transistor are configured to be selectively switched on or off based on a status signal of the power switch, respectively, to enable the clamp protection circuit to initiate different clamp protection modes.
Optionally, the first power tube and the second power tube respectively comprise three terminals,
wherein a first terminal of the first power tube is connected to the input terminal, a second terminal of the first power tube is connected to the power supply terminal, and a third terminal of the first power tube is connected to the clamp protection terminal,
wherein a first terminal of the second power tube is connected to the input terminal, a second terminal of the second power tube is grounded, and a third terminal of the second power tube is connected to the clamp protection terminal.
Optionally, the clamp protection circuit further includes a diode, an anode of the diode is connected to the clamp protection terminal, and a cathode of the diode is connected to the third terminals of the first power tube and the second power tube.
Optionally, the clamp protection circuit further comprises a first resistor connected between the first terminal of the first power transistor and the second terminal of the first power transistor.
Optionally, the clamp protection circuit further comprises a second resistor connected between the second terminal of the second power transistor and the third terminal of the second power transistor.
Optionally, the first power transistor is a P-channel MOSFET.
Optionally, the first terminal of the first power transistor is a gate of the P-channel MOSFET, the second terminal of the first power transistor is a source of the P-channel MOSFET, and the third terminal of the first power transistor is a drain of the P-channel MOSFET.
Optionally, the second power transistor is an N-channel MOSFET.
Optionally, the first terminal of the second power transistor is a gate of the N-channel MOSFET, the second terminal of the second power transistor is a source of the N-channel MOSFET, and the third terminal of the second power transistor is a drain of the N-channel MOSFET.
According to a second aspect of the present invention, there is provided an in-vehicle electronic apparatus including: an MCU comprising one or more pins; a signal detection circuit configured to detect a switch control signal for a power switch and output a state signal of the power switch based on the switch control signal; and a clamp protection circuit as described above.
The clamp protection circuit according to the present invention has advantages in that:
two different clamping modes can be formed for the high and low voltages of the power switch by using only a simple power tube combination (and optionally a combination of a power tube, a diode and a resistor), and compared with the traditional solution, the adopted circuit components are fewer and the cost is lower;
because the clamping current loop is formed by using the MOSFET, the clamping protection circuit can bear larger current and can be expanded into a multi-path (can be easily expanded into nearly one hundred paths) I/O pin protection circuit, and the clamping protection circuit is particularly suitable for a multi-pin ARM core MCU which is commonly used in the market;
when the device is in a sleep state, the clamp protection circuit can be made to draw little current from the MCU internal power supply by setting the reference voltage of the clamp power supply equal to the high level voltage of the signal detection circuit of the power switch, with no power consumption requirement on the MCU internal power supply.
Drawings
Fig. 1 shows a circuit schematic diagram of an MCU in abnormal operation with the MCU power off.
Fig. 2 shows a schematic diagram of a clamp protection circuit for a vehicle MCU according to an exemplary embodiment of the present invention.
Fig. 3 shows a schematic diagram of the application of the clamp protection circuit according to the present invention to a plurality of I/O pins of a vehicle MCU.
Detailed Description
A clamp protection circuit according to the present invention will be described below by way of embodiments with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention to those skilled in the art. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details. Rather, it is contemplated that the utility model may be practiced with any combination of the following features and elements, whether or not they relate to different embodiments. Thus, the following aspects, features, embodiments and advantages are merely illustrative and should not be considered elements or limitations of the claims except where explicitly recited in a claim(s).
Fig. 2 shows a schematic diagram of a clamp protection circuit for a vehicle MCU according to an exemplary embodiment of the present invention. The clamp protection circuit is provided in an in-vehicle electronic apparatus including an MCU having one or more pins (I/O interfaces), the MCU being connected to a power supply via a power switch, the in-vehicle electronic apparatus being operable to detect a switch control signal for the power switch by means of a signal detection circuit and to thereby provide a status signal of the power switch.
Specifically, the clamp protection circuit is arranged between a signal detection circuit of the vehicle-mounted electronic equipment and the MCU, and is configured to start different clamp protection modes based on a state signal of the power switch provided by the signal detection circuit so as to provide different overvoltage protection functions for pins of the MCU.
As shown in fig. 2, the Clamp protection circuit according to the present embodiment includes an input terminal a, a Clamp protection terminal B, and a power supply terminal VCC _ Clamp, where the input terminal a is connected to the signal detection circuit for receiving a status signal of the power switch; the clamping protection end B is connected to one or more pins of the vehicle MCU and is used for providing clamping protection for the vehicle MCU; the power supply terminal VCC _ Clamp is connected to an external Clamp power supply for providing a reference potential for Clamp protection operation of the circuit.
The clamp protection circuit is mainly composed of a first power tube Q1 and a second power tube Q2, which can be selectively switched on or off respectively based on a state signal of a power switch provided by a signal detection circuit, so that the clamp protection circuit starts different clamp protection modes.
In an exemplary embodiment, the first power transistor Q1 is formed as a P-channel MOSFET and the second power transistor Q2 is formed as an N-channel MOSFET.
Referring to fig. 2, the gate of the first power transistor Q1 is connected to the input terminal a of the Clamp protection circuit, the source of the first power transistor Q1 is connected to the power supply terminal VCC _ Clamp of the Clamp protection circuit, and the drain of the first power transistor Q1 is connected to the Clamp protection terminal B of the Clamp protection circuit.
The gate of the second power transistor Q2 is connected to the input terminal a of the clamp protection circuit, the source of the second power transistor Q2 is grounded, and the drain of the second power transistor Q2 is connected to the clamp protection terminal B of the clamp protection circuit.
Optionally, the clamp protection circuit may further include a diode D1, an anode of the diode D1 is connected to the clamp protection terminal B, and a cathode of the diode D1 is connected to the drains of the first power transistor Q1 and the second power transistor Q2.
The clamp protection circuit may further include a first resistor R1 connected between the gate and source of the first power transistor Q1.
Optionally, the clamp protection circuit may further include a second resistor R2 connected between the source and the drain of the second power transistor Q2.
The operation of the clamp protection circuit in different switching states of the power switch is described in detail below with reference to fig. 2.
When the signal detection circuit outputs a low level based ON the switch control signal, the power switch is turned ON (the switching state is "ON"), the MCU normally operates, and the input terminal a of the clamp protection circuit receives a low level signal, so Q2 is turned off and Q1 is turned ON. At this time, the voltage Vb at the Clamp protection terminal B is the sum of the reference voltage VCC _ Clamp provided by the Clamp power supply and the on-state voltage Vd1 of the diode D1, that is, Vb equals to VCC _ Clamp + Vd 1.
The reference voltage VCC _ Clamp provided by the Clamp power supply can be determined according to the maximum allowable input voltage of the corresponding I/O pin of the MCU. Specifically, in practical application, for example, for an I/O pin of 3.3V, VCC _ Clamp + Vd1 can be set to be less than or equal to 3.3V; for the pin of 5V I/O, VCC _ Clamp + Vd1 can be set to be less than or equal to 5V.
Based on the above circuit configuration, if an external device inputs a high voltage interference signal to the I/O pin, the over-voltage clamp protection of the clamp protection terminal B may be activated.
When the signal detection circuit outputs a high level based on the switch control signal, the power switch is turned OFF (the switching state is "OFF"), the MCU is powered OFF, and the input terminal a of the clamp protection circuit receives the high level signal, so that Q1 is turned OFF and Q2 is turned on. At this time, the voltage Vb at the clamp protection terminal B is the on voltage Vd1 of the diode D1, that is, Vb equals Vd 1.
Specifically, in practical application, assuming that the on voltage of the diode D1 is 0.2V, the clamp protection terminal voltage Vb is pulled down to 0.2V, so as to prevent the current of the external device from flowing into the internal power supply of the MCU through the I/O pin of the MCU, thereby avoiding abnormal start-up of the MCU.
According to an alternative embodiment, since the clamp protection circuit according to the present invention uses the MOSFET as a clamp current loop, it can bear a larger current, and thus can be extended to a multi-channel (nearly one hundred channels) I/O interface protection circuit. As shown in FIG. 3, the expanding circuit can implement clamping protection measures on a plurality of I/O pins of the MCU at the same time with lower cost and higher safety factor, and is particularly suitable for an ARM core MCU with multiple pins. Fig. 3 schematically shows a 4-way I/O port protection circuit, but the present invention is not limited thereto, but can be extended as much as a hundred-way I/O port protection circuit as described above.
The clamp protection circuit according to the present invention as described with reference to fig. 2 and 3 is capable of performing overvoltage clamp protection on an I/O pin of an MCU when an on-vehicle electronic device, particularly, an MCU thereof is in an operating state (an external power is turned on), thereby preventing damage of the MCU due to a large voltage interference signal on the I/O pin flowing into the inside of the MCU; in addition, when the device is in a dormant state (external power supply is cut off), the clamping protection circuit can also perform ground protection on the I/O pin of the MCU, so that high levels output by other external devices in the vehicle electrical system are prevented from flowing into the MCU through the I/O pin of the MCU, and abnormal starting of the MCU is prevented from being caused.
The clamp protection circuit according to the present invention has the advantage that two different clamp modes can be formed for high and low voltages of the power switch by using only a simple power transistor combination (and optionally a combination of a power transistor, a diode and a resistor), and compared with a traditional solution, the adopted circuit components are fewer and the cost is lower.
In addition, because the MOSFET is used as a clamping current loop, the current born by the clamping protection circuit is larger, so that the clamping protection circuit can be expanded into a multi-path (can be easily expanded into nearly one hundred paths) I/O pin protection circuit, and the clamping protection circuit is particularly suitable for a multi-pin ARM core MCU which is commonly used in the market.
In particular, when the device is in a sleep state (Q2 on, Q1 off), by setting the reference voltage VCC _ Clamp of the Clamp power supply equal to the high level voltage of the signal detection circuit of the power switch, the Clamp protection circuit can be made to draw little current from the MCU internal power supply, requiring no power consumption from the MCU internal power supply.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. It should be understood that the features disclosed in the above embodiments may be used alone or in combination, except where specifically noted. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the utility model. Therefore, it is intended that the utility model disclosed herein not be limited to the particular embodiments disclosed, but that it will include modifications within the spirit and scope of the present invention as defined by the appended claims.
Claims (10)
1. A clamp protection circuit for a vehicle MCU, the clamp protection circuit comprising:
an input (A) connected to a power switch;
a clamp protection terminal (B) connected to one or more pins of a vehicle MCU;
a power supply terminal (VCC _ Clamp) connected to an external Clamp power supply; and
a first power transistor (Q1) and a second power transistor (Q2), wherein the first power transistor (Q1) and the second power transistor (Q2) are configured to be selectively switched on or off based on a status signal of the power switch, respectively, to enable the clamp protection circuit to enable different clamp protection modes.
2. The clamp protection circuit of claim 1, wherein the first power transistor and the second power transistor each comprise three terminals,
wherein a first terminal of the first power tube is connected to the input terminal (A), a second terminal of the first power tube is connected to the power supply terminal (VCC _ Clamp), a third terminal of the first power tube is connected to the Clamp protection terminal (B),
wherein a first terminal of the second power tube is connected to the input end (A), a second terminal of the second power tube is grounded, and a third terminal of the second power tube is connected to the clamp protection end (B).
3. The clamp protection circuit of claim 2, further comprising a diode (D1), an anode of the diode being connected to the clamp protection terminal (B), and a cathode of the diode being connected to the third terminals of the first and second power transistors.
4. The clamp protection circuit of claim 2 or 3, further comprising a first resistor (R1) connected between the first terminal of the first power transistor and the second terminal of the first power transistor.
5. The clamp protection circuit of claim 2 or 3, further comprising a second resistor (R2) connected between the second terminal of the second power transistor and the third terminal of the second power transistor.
6. The clamp protection circuit of claim 2 or 3, wherein the first power transistor is a P-channel MOSFET.
7. The clamp protection circuit of claim 6, wherein the first terminal of the first power transistor is a gate of the P-channel MOSFET, the second terminal of the first power transistor is a source of the P-channel MOSFET, and the third terminal of the first power transistor is a drain of the P-channel MOSFET.
8. The clamp protection circuit of claim 2 or 3, wherein the second power transistor is an N-channel MOSFET.
9. The clamp protection circuit of claim 8, wherein the first terminal of the second power transistor is a gate of the N-channel MOSFET, the second terminal of the second power transistor is a source of the N-channel MOSFET, and the third terminal of the second power transistor is a drain of the N-channel MOSFET.
10. An in-vehicle electronic apparatus, characterized by comprising:
an MCU comprising one or more pins;
a signal detection circuit configured to detect a switch control signal for a power switch and output a state signal of the power switch based on the switch control signal; and
the clamp protection circuit of any one of claims 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202220354582.3U CN216751189U (en) | 2022-02-22 | 2022-02-22 | Clamp protection circuit and vehicle-mounted electronic equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202220354582.3U CN216751189U (en) | 2022-02-22 | 2022-02-22 | Clamp protection circuit and vehicle-mounted electronic equipment |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN216751189U true CN216751189U (en) | 2022-06-14 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202220354582.3U Active CN216751189U (en) | 2022-02-22 | 2022-02-22 | Clamp protection circuit and vehicle-mounted electronic equipment |
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| Country | Link |
|---|---|
| CN (1) | CN216751189U (en) |
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- 2022-02-22 CN CN202220354582.3U patent/CN216751189U/en active Active
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