CN214097526U

CN214097526U - Sampling circuit for current mode speed sensor

Info

Publication number: CN214097526U
Application number: CN202023063069.9U
Authority: CN
Inventors: 吴宏达; 黄腾云; 刘斌彬; 陈敏杰
Original assignee: United Automotive Electronic Systems Co Ltd
Current assignee: United Automotive Electronic Systems Co Ltd
Priority date: 2020-12-17
Filing date: 2020-12-17
Publication date: 2021-08-31
Anticipated expiration: 2030-12-17

Abstract

The utility model provides a sampling circuit for a current type speed sensor, which comprises a sampling branch circuit connected between a wiring end and the ground and a triggering branch circuit connected between the wiring end and a power supply voltage; when the current type speed sensor works normally, the trigger branch circuit is in an open state and controls and maintains the sampling branch circuit to be in the open state, so that the sampling circuit samples a current signal at the output end of the current type speed sensor and converts the current signal into a voltage signal; when short circuit occurs, the trigger branch circuit is disconnected and the sampling branch circuit is locked to be in a closed state; when the sampling branch is recovered to be in the normal state, the sampling branch is triggered to be recovered to be in the open state through an external pulse signal, and when the sampling branch is recovered to be in the open state, the sampling branch is recovered to be in the open state and is maintained to be in the open state, so that sampling is continued. The utility model discloses can turn-off sampling circuit fast when short-circuit fault, avoid short-circuit current to influence the problem of damage even to the consumption of the device of sampling branch road.

Description

Sampling circuit for current mode speed sensor

Technical Field

The utility model relates to a sensor technical field, in particular to a sampling circuit for current type speedtransmitter.

Background

The current type speed sensor is a current type speed sensor with high and low signal output states corresponding to different current intervals. However, it is common for the microprocessor to detect a voltage signal, which requires the conversion of the current signal into a voltage signal. Referring to fig. 1, a sampling circuit of a current mode speed sensor in the prior art includes a terminal Pin connected to an output terminal of the current mode speed sensor, and a sampling resistor R1 connected between the terminal Pin and ground. A second resistor R2 is connected to a common intersection point of the sampling resistor R1 and the terminal Pin, a second capacitor C2 is connected between the other end of the second resistor R2 and the ground, and the second resistor R2 and the second capacitor C2 form an RC filter circuit. The RC filter circuit is connected to one input of the comparator or to the IO interface of the microprocessor (not shown). When the RC filter circuit is connected with the comparator, the output end of the comparator is connected with the IO interface of the microprocessor. The current signal of the output end of the current type speed sensor is converted into a voltage signal S2 through a terminal Pin and a sampling resistor R1, and the voltage signal S2 is transmitted to one input end of a comparator or an IO interface of a microprocessor such as an MCU through an RC filter circuit. If the terminal Pin is short-circuited to a power Supply (SCB), the power of the sampling resistor R1 becomes large, so the sampling resistor R1 generally selects a resistor with larger power or selects a plurality of resistors to be connected in parallel. In order to avoid the influence and even damage to the power of the sampling resistor when the SCB fails, a switching tube K1 is connected in series with the sampling resistor R1 in the prior art. The following describes a series relationship between the switching transistor K1 and the sampling resistor R1, taking the switching transistor K1 of the bipolar transistor as an example. Referring to fig. 1, the switch tube K1 may be connected to the lower end of the sampling resistor R1, and at this time, the collector of the switch tube K1 is connected to the sampling resistor R1, the emitter of the switch tube K1 is grounded to GND, and the base of the switch tube K1 is connected to the microprocessor (not shown) through the third resistor R3. Referring to fig. 2, the switch tube K1 may also be connected to the upper end of the sampling resistor R1, at this time, the collector of the switch tube K1 is connected to the terminal Pin, the emitter of the switch tube K1 is connected to the sampling resistor R1, and the base of the switch tube K1 is connected to the microprocessor (not shown) through the third resistor R3. The second capacitor C2 is also connected between the other end of the second resistor R2 and ground, and the second resistor R2 and the second capacitor C2 form an RC filter circuit. When an SCB fault is detected, the microprocessor sends a control signal S1 to immediately cut off the switch tube K1, so that the switch tube K1 is in a cut-off state, and the R1 is prevented from being damaged by the fault of short circuit to the power supply. When the SCB fails, the software of the microprocessor detects and responds (turns off K1) for a long time (millisecond level), which causes a large transient current to flow through the sampling resistor R1 and the switching tube K1, so the circuit design has a high requirement on the power level of the sampling resistor R1, a high requirement on the current capability of the switching tube K1, and finally the total chip area and the cost are high.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a sampling circuit for current type speedtransmitter to turn-off sampling circuit fast when short-circuit fault avoids the problem that short-circuit current influences damage even to the consumption of the device of sampling branch road.

In order to solve the above technical problem, the utility model provides a sampling circuit for current type speedtransmitter, include: the sampling branch circuit is connected between the terminal and the ground, and the trigger branch circuit is connected between the terminal and the power supply voltage; when the sampling circuit works normally, the trigger branch is in an open state, the trigger branch controls the sampling branch to be in the open state and maintains the sampling branch to be in the open state, so that the sampling circuit samples a current signal at the output end of the current type speed sensor and converts the current signal into a voltage signal; when the output end of the current type speed sensor is short-circuited with a power supply, the sampling branch is disconnected and locked to be in a closed state by disconnecting the trigger branch; when the output end of the current type speed sensor and the power supply are recovered to be normal, the sampling branch circuit is triggered to recover to an open state through an external pulse signal, and when the sampling branch circuit recovers to the open state, the triggering branch circuit recovers to the open state and maintains the sampling branch circuit to be in the open state so as to continue sampling the current signal of the output end of the current type speed sensor and convert the current signal into a voltage signal.

Furthermore, the utility model provides a sampling circuit for current type speed sensor, including NPN type transistor and PNP type transistor, the projecting pole or the source ground of NPN type transistor, the collecting electrode or the drain-source resistance of NPN type transistor are connected in the wiring end through sampling resistor, the base or the grid of NPN type transistor is through fourth resistance ground connection, the base or the grid of NPN type transistor still passes through third resistance and connects in the collecting electrode or the drain-source resistance of PNP type transistor, the projecting pole or the source resistance of PNP type transistor connect supply voltage, the base or the grid of PNP type transistor connects supply voltage through sixth resistance, the base or the grid of PNP type transistor still connects in the wiring end through fifth resistance, the collecting electrode or the drain-source resistance of PNP type transistor has external pulse signal through first diode reverse connection, the common connection point of sampling resistor and wiring end is the sampling node of sampling branch road, the voltage signal of the sampling node is smaller than the power supply voltage; the sampling resistor, the third resistor, the fourth resistor and the NPN type transistor form a sampling branch circuit, and the fifth resistor, the sixth resistor, the first diode of the PNP type transistor and an external pulse signal form a trigger branch circuit.

Furthermore, the utility model provides a sampling circuit for current type speed sensor, including NPN type transistor and PNP type transistor, the projecting pole or the source of NPN type transistor pass through sampling resistor ground connection, the collecting electrode or the drain electrode of NPN type transistor are connected at the wiring end, the base or the grid of NPN type transistor pass through fourth resistance and connect the projecting pole or the source electrode of NPN type transistor, the base or the grid of NPN type transistor still pass through third resistance and connect the collecting electrode or the drain electrode of PNP type transistor, the projecting pole or the source electrode of PNP type transistor connect supply voltage, the base or the grid of PNP type transistor connect supply voltage through sixth resistance, the base or the grid of PNP type transistor still connect at the wiring end through fifth resistance, the collecting electrode or the drain electrode of PNP type transistor have external pulse signal through first diode reverse connection, a common connection point of the sampling resistor and an emitter or a source of the NPN transistor is a sampling node of the sampling branch, and a voltage signal of the sampling node is smaller than the power supply voltage; the sampling resistor, the third resistor, the fourth resistor and the NPN type transistor form a sampling branch circuit, and the fifth resistor, the sixth resistor, the PNP type transistor, the first diode and an external pulse signal form a trigger branch circuit.

Further, the utility model provides a sampling circuit for current mode speedtransmitter, be connected with electrostatic discharge electric capacity between wiring end and the ground.

Further, the utility model provides a sampling circuit for current type speedtransmitter, sampling resistance is single resistance, series resistance, parallel resistance or series-parallel resistance.

Furthermore, the utility model provides a sampling circuit for current type speedtransmitter, the common crossing point of sampling resistance and wiring end is connected and is passed through filter circuit and connect an input of comparator, reference voltage signal is connected to another input of comparator, the output connection microprocessor's of comparator I/O interface; the sampling resistor samples a current signal at the output end of the current type speed sensor and converts the current signal into a voltage signal, the voltage signal is output to the comparator through the filter circuit, and the comparator compares the voltage signals at the two input ends and outputs the voltage signals to the microprocessor.

Furthermore, the utility model provides a sampling circuit for current type speedtransmitter, the common intersection point of sampling resistance and wiring end is connected with the I/O interface of microprocessor through the filter circuit; the sampling resistor samples a current signal at the output end of the current type speed sensor and converts the current signal into a voltage signal which is output to the microprocessor through the filter circuit.

Further, the utility model provides a sampling circuit for current mode speedtransmitter, microprocessor is connected to the anode terminal of first diode, and when current mode speedtransmitter's output and power resume normal, microprocessor exports external pulse signal.

Further, the utility model provides a sampling circuit for current mode speed sensor, NPN type transistor is bipolar transistor or field effect transistor.

Further, the utility model provides a sampling circuit for current mode speedtransmitter, PNP type transistor is bipolar transistor or field effect transistor.

Compared with the prior art, the utility model samples the current signal at the output end of the current type speed sensor and converts the current signal into a voltage signal when the trigger branch and the sampling branch are opened simultaneously; and when the trigger branch and the sampling branch are in a closed state at the same time, stopping sampling the current signal at the output end of the current type speed sensor. When short-circuit fault occurs, the trigger branch circuit immediately disconnects the sampling circuit without waiting for the response period of detection and operation of the microprocessor, so that the sampling circuit is quickly turned off and sampling is stopped, instantaneous large current during short circuit cannot flow through the sampling branch circuit, and the possibility of power consumption influence and even damage to devices in the sampling branch circuit is avoided.

Drawings

FIG. 1 is a schematic diagram of a sampling circuit of a current mode speed sensor according to one embodiment of the prior art;

FIG. 2 is a schematic diagram of a sampling circuit of a current mode speed sensor according to one embodiment of the prior art;

fig. 3 is a schematic diagram of a sampling circuit of a current mode speed sensor according to an embodiment of the present invention;

fig. 4 is a schematic diagram of a sampling circuit of a current mode speed sensor according to an embodiment of the present invention;

fig. 5 is a schematic diagram of the connection relationship between the filter circuit and the comparator and the microprocessor according to an embodiment of the present invention;

fig. 6 is a schematic diagram illustrating a connection relationship between a filter circuit and a microprocessor according to an embodiment of the present invention;

fig. 7 is a schematic diagram of the microprocessor outputting an external pulse signal according to an embodiment of the present invention.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more fully apparent from the following description and appended claims. It should be noted that the drawings are in simplified form and are not to precise scale, and are provided for convenience and clarity in order to facilitate the description of the embodiments of the present invention.

The utility model provides a sampling circuit for current type speedtransmitter, include: the sampling branch circuit is connected between the terminal and the ground, and the trigger branch circuit is connected between the terminal and the power supply voltage; when the sampling circuit works normally, the trigger branch is in an open state, the trigger branch controls the sampling branch to be in the open state and maintains the sampling branch to be in the open state, so that the sampling circuit samples a current signal at the output end of the current type speed sensor and converts the current signal into a voltage signal; when the output end of the current type speed sensor is short-circuited with a power supply, the sampling branch is disconnected and locked to be in a closed state by disconnecting the trigger branch; when the output end of the current type speed sensor and the power supply are recovered to be normal, the sampling branch circuit is triggered to recover to an open state through an external pulse signal, and when the sampling branch circuit recovers to the open state, the triggering branch circuit recovers to the open state and maintains the sampling branch circuit to be in the open state so as to continue sampling the current signal of the output end of the current type speed sensor and convert the current signal into a voltage signal.

When the trigger branch and the sampling branch are in the open state simultaneously, the current signal at the output end of the current type speed sensor is sampled and converted into a voltage signal; and when the trigger branch and the sampling branch are in a closed state at the same time, stopping sampling the current signal at the output end of the current type speed sensor. When short-circuit fault occurs, the trigger branch circuit immediately disconnects the sampling circuit without waiting for the response period of detection and operation of the microprocessor, so that the sampling circuit is quickly turned off and sampling is stopped, instantaneous large current during short circuit cannot flow through the sampling branch circuit, and the possibility of power consumption influence and even damage to devices in the sampling branch circuit is avoided.

Example one

Referring to fig. 3, the sampling circuit for a current type speed sensor according to this embodiment includes an NPN transistor Q1 and a PNP transistor Q2, an emitter or a source of the NPN transistor Q1 is grounded GND, a collector or a drain of the NPN transistor Q1 is connected to a terminal Pin through a sampling resistor R1, a base or a gate of the NPN transistor Q1 is grounded GND through a fourth resistor R4, a base or a gate of the NPN transistor Q1 is further connected to a collector or a drain of the PNP transistor Q2 through a third resistor R3, an emitter or a source of the PNP transistor Q2 is connected to a supply voltage VDD, a base or a gate of the PNP transistor Q2 is connected to the supply voltage VDD through a sixth resistor R6, a base or a gate of the PNP transistor Q2 is further connected to the terminal Pin through a fifth resistor R5, a collector or a drain of the PNP transistor Q2 is connected to an external pulse signal S1 through a first diode D1 in a reverse direction, the common connection point of the sampling resistor R1 and the terminal Pin is a sampling node of the sampling branch, and a voltage signal of the sampling node is smaller than the power supply voltage VDD; the sampling resistor R1, the third resistor R3, the fourth resistor R4 and the NPN transistor Q1 form a sampling branch, and the fifth resistor R5, the sixth resistor R6, the first diode D1 of the PNP transistor Q2 and an external pulse signal S1 form a trigger branch.

The working principle of the first embodiment is as follows:

and is connected with the output end of the current type speed sensor through a terminal Pin. In normal operation, the current signal i flows through the sampling resistor R1 and the fifth resistor R5, the base or gate voltage of the NPN transistor Q1 is 0, the NPN transistor Q1 is in an off state, the base or gate voltage of the PNP transistor Q2 is the voltage flowing through the fifth resistor R5, i.e., the voltage signal at the sampling node is lower than the supply voltage VDD at the emitter or source of the PNP transistor Q2, the PNP transistor Q2 is in a conductive state, the collector or drain voltage of the PNP transistor Q2 is the power voltage, which forms a loop through the third resistor R3, the fourth resistor R4 and ground, the base or gate of the NPN transistor Q1 gets the voltage, since the emitter or the source of the NPN transistor Q1 is grounded, the NPN transistor Q1 is in a conducting state, and at this time, the NPN transistor Q1 turns on the path of the sampling resistor R1, and the sampling resistor R1 samples the output current i at the output terminal of the current speed sensor and converts the output current i into the voltage signal S2. The collector or drain voltage of the PNP transistor Q2 maintains the NPN transistor Q1 in a conducting state, so that the sampling branch maintains an open state for sampling.

When the output of the current mode speed sensor (terminal Pin) is shorted to a power supply (which is typically greater than or equal to the supply voltage VDD of the sampling circuit), the voltage signal of the sampling node is the voltage of the base or gate of the PNP transistor Q2 and is greater than or equal to the supply voltage VDD connected to the emitter or source of the PNP transistor Q2, so that the PNP transistor Q2 is in the off state, and at this time, the voltage of the collector or drain of the PNP transistor Q2 is 0, the voltage of the path between the collector or drain of the PNP transistor Q2 and the third resistor R3, the fourth resistor R4, and ground is 0, which results in the voltage at the base or gate of the NPN transistor Q1 being 0, turning off the NPN transistor Q1, thereby closing the path between the sampling resistor R1 and ground, the sampling branch is turned from the open state to the closed state and the locking sampling branch is maintained in the closed state. At this time, the voltage on the sampling branch is in a fault state. That is to say, when the output end of the current type speed sensor is short-circuited with the power supply, the PNP transistor Q2 is in an off state, and the NPN transistor Q1 is immediately triggered to be also in the off state, so that a response period required by detection and operation of the microprocessor is not required, and the sampling branch is quickly turned off and stops sampling, and then an instantaneous large current during short-circuiting does not flow through the sampling branch, thereby avoiding the possibility of power consumption influence and even damage to devices in the sampling branch, such as the sampling resistor R1 and the NPN transistor Q1. That is, the triggering branch of the first embodiment is a hardware triggering circuit, and the response period is fast. By adopting the sampling circuit of the first embodiment, the requirement on the power consumption of the sampling resistor R1 is not high, a large resistor with large bearing power consumption and large volume is not needed, and the requirements on the current parameters and the power parameters of the transistors Q1 and Q2 are also low because the two transistors Q1 and Q2 are turned off quickly. Because the power consumption of the sampling resistor R1 is low, a resistor with low power and small volume can be used, so that the cost is reduced, and the occupied area of the sampling resistor R1 in a Printed Circuit Board (PCB) is reduced.

When the output end of the current type speed sensor and the power supply are restored to be normal, an external pulse signal S1 inputs a pulse voltage signal to the base or the gate of the NPN type transistor Q1 through the first diode D1, the NPN type transistor Q1 is restored to a conducting state, the sampling resistor is turned on, the sampling branch is triggered to be restored to the open state, at this time, the voltage signal of the sampling node is lower than the emitter or source supply voltage VDD of the PNP type transistor Q2, and the PNP type transistor Q2 is restored to the conducting state, so that the NPN type transistor Q1 is maintained to be in the conducting state through the PNP type transistor Q2, the NPN type transistor Q1 is turned on the sampling resistor R1 to enable the sampling branch formed by the NPN type transistor Q2 to be in the open state, and the current signal at the output end of the current type speed sensor is continuously sampled and converted into the voltage signal.

Because the transistors Q1 and Q2 are in the high-impedance state when short-circuited, when the output end of the current type speed sensor and the power supply are restored to normal, that is, when the short-circuit fault disappears, the transistors Q1 and Q2 are still in the high-impedance state, at this time, the voltage signal of the sampling node cannot trigger the transistor Q2 to be turned on, and the transistor Q1 cannot be triggered to be turned on by the transistor Q1, so that the external pulse signal S1 is required to trigger the transistor Q1 to be turned from the high-impedance state to the conducting state, after the transistor Q1 is turned on, the voltage of the sampling node is lower than the power supply voltage VDD of the emitter or the source of the transistor Q2, and the transistor Q2 is restored to the conducting state from the high-impedance state. When the sampling branch is locked in the off state, the NPN transistor Q1 can be unlocked to return to the on state through the unidirectional conduction characteristic of the external pulse signal S1 through the first diode D1, and after the external trigger signal S1 is ended, the first diode D1 is used to prevent the external pulse signal S1 from causing interference and other adverse effects on the trigger branch.

In the sampling circuit of the first embodiment, the switching speeds of the transistors Q1 and Q2 are in the nanosecond or microsecond level, and when the SCB fails, the response time of the trigger branch is at most in the microsecond level, so that the requirement on the power consumption of the sampling resistor R1 is low, the R1 only needs to adopt a resistor packaged conventionally, and the requirement on the current capacities of the transistors Q1 and Q2 is also low. There are integrated chips for many vendors of this part of the circuit. The circuit area of the whole module can be greatly reduced, and the cost can be greatly reduced.

Referring to fig. 3, in the sampling circuit for a current-mode speed sensor according to the first embodiment, an electrostatic discharge capacitor C1 is connected between the terminal Pin and the ground GND. The electrostatic discharge capacitor C1 has an electrostatic protection function.

In the sampling circuit for a current-type speed sensor provided in this embodiment, the sampling resistor R1 may be a single resistor, a series resistor, a parallel resistor, or even a series-parallel resistor. No matter the resistor is a single resistor or a series-parallel resistor, the power of the resistor is not high, and the transient large current caused by short circuit to a power supply does not need to be borne by a high-power resistor.

Referring to fig. 3 and 5, in the sampling circuit for a current-mode speed sensor according to the first embodiment, a common intersection point between the sampling resistor R1 and the terminal Pin is connected to an input terminal of the comparator 100 through a second resistor R2, another input terminal of the comparator 100 is connected to a reference voltage signal Vref, an output terminal of the comparator 100 is connected to an I/O interface of the microprocessor 200, a second capacitor C2 is further connected between the common intersection point between the second resistor R2 and the comparator 100 and the ground, and the second resistor R2 and the second capacitor C2 form an RC filter circuit; the sampling resistor R1 samples the current signal i at the output terminal of the current-mode speed sensor and converts the current signal into a voltage signal S2, and the voltage signal is output to the comparator 100 through the second resistor R2, and the comparator 100 compares the voltage signals at the two input terminals and outputs the voltage signal to the microprocessor 200. The arrangement of comparator 100 may increase the stability of the signal received by the microprocessor. The voltage signal S2 can be converted into a digital signal for monitoring or operation by the microprocessor 200. The comparator 100 of the present embodiment is preferably a hysteresis comparator, which has the effect of improving the interference rejection capability.

Referring to fig. 3 and fig. 6, in the sampling circuit for a current-mode speed sensor according to the first embodiment, a common intersection point between a sampling resistor R1 and a terminal Pin is connected to an I/O interface of a microprocessor 200 through a second resistor R2, a second capacitor C2 is further connected between the common intersection point between the second resistor R2 and the microprocessor 200 and ground, and the second resistor R2 and the second capacitor C2 form an RC filter circuit; the sampling resistor R1 samples the current signal i at the output terminal of the current-type speed sensor and converts the current signal i into a voltage signal S2, which is output to the microprocessor 200 through the second resistor R2. Wherein the microprocessor may monitor, operate on, or retransmit the voltage signal S2 to the next node. The microprocessor 200 may be an MCU, a DSP, a CPLD, an FPGA, or the like.

Referring to fig. 3 and fig. 7, in the sampling circuit for a current-mode speed sensor provided in the first embodiment, an anode terminal of the first diode D1 is connected to the microprocessor 200, and when the output terminal of the current-mode speed sensor and the power supply voltage VDD return to normal, the microprocessor 200 outputs an external pulse signal S1. Of course, the external pulse signal S1 may be other sources.

The filter circuit in the first embodiment includes, but is not limited to, an RC filter circuit, and may also include other filter circuits such as CRC.

The utility model provides a sampling circuit for current mode speedtransmitter, NPN type transistor Q1 is bipolar transistor or field effect transistor. The PNP transistor Q2 is a bipolar transistor or a field effect transistor.

Example two

Referring to fig. 4 to 7, the sampling circuit for a current type speed sensor provided in the second embodiment includes an NPN transistor Q1 and a PNP transistor Q2, an emitter or a source of the NPN transistor Q1 is connected to GND through a sampling resistor R1, a collector or a drain of the NPN transistor Q1 is connected to a terminal Pin, a base or a gate of the NPN transistor Q1 is connected to the emitter or the source of the NPN transistor Q1 through a fourth resistor R4, the base or the gate of the NPN transistor Q1 is further connected to the collector or the drain of the PNP transistor Q2 through a third resistor R3, the emitter or the source of the PNP transistor Q2 is connected to a supply voltage VDD, the base or the gate of the PNP transistor Q2 is connected to a supply voltage VDD through a sixth resistor R6, the base or the gate of the PNP transistor Q2 is further connected to the terminal Pin through a fifth resistor R5, the collector or the drain of the PNP transistor Q2 is reversely connected with an external pulse signal S1 through a first diode D1, a common connection point of the sampling resistor R1 and the emitter or the source of the NPN transistor Q1 is a sampling node of the sampling branch, and a voltage signal of the sampling node is smaller than the supply voltage VDD voltage; the sampling resistor R1, the third resistor R3, the fourth resistor R4 and the NPN transistor Q1 form a sampling branch, and the fifth resistor R5, the sixth resistor R6, the PNP transistor Q2, the first diode D1 and the external pulse signal S1 form a trigger branch.

The operating principle and the function of the second embodiment are the same as those of the first embodiment, and the difference is that the connection position of the NPN transistor Q1 in the sampling branch and the sampling resistor R1 is changed, that is, the NPN transistor Q1 in the sampling branch of the first embodiment is located at the lower end of the sampling resistor R1, and the NPN transistor Q1 in the sampling branch of the second embodiment is located at the upper end of the sampling resistor R1. The connection relationship and the function of the second resistor R2 and the second capacitor C2 are the same as those of the first embodiment.

The utility model discloses after the SCB trouble took place for current type speedtransmitter circuit, its turn-off time shortened to microsecond level or nanosecond level by former millisecond level to avoided the damage that causes sampling circuit, can satisfy the strict requirement of ISO26262 function safety.

The present invention is not limited to the above embodiments, and any changes or decorations within the scope of the claims of the present invention are within the protection scope of the present invention.

Claims

1. A sampling circuit for a current mode speed sensor, comprising:

the sampling branch circuit is connected between the terminal and the ground, and the trigger branch circuit is connected between the terminal and the power supply voltage;

when the sampling circuit works normally, the trigger branch is in an open state, the trigger branch controls the sampling branch to be in the open state and maintains the sampling branch to be in the open state, so that the sampling circuit samples a current signal at the output end of the current type speed sensor and converts the current signal into a voltage signal;

when the output end of the current type speed sensor is short-circuited with a power supply, the sampling branch is disconnected and locked to be in a closed state by disconnecting the trigger branch;

when the output end of the current type speed sensor and the power supply are recovered to be normal, the sampling branch circuit is triggered to recover to an open state through an external pulse signal, and when the sampling branch circuit recovers to the open state, the triggering branch circuit recovers to the open state and maintains the sampling branch circuit to be in the open state so as to continue sampling the current signal of the output end of the current type speed sensor and convert the current signal into a voltage signal.

2. The sampling circuit for the amperometric speed sensor according to claim 1, comprising an NPN type transistor and a PNP type transistor, wherein the emitter or the source of the NPN type transistor is grounded, the collector or the drain of the NPN type transistor is connected with a terminal through a sampling resistor, the base or the gate of the NPN type transistor is grounded through a fourth resistor, the base or the gate of the NPN type transistor is further connected with the collector or the drain of the PNP type transistor through a third resistor, the emitter or the source of the PNP type transistor is connected with a supply voltage, the base or the gate of the PNP type transistor is connected with the supply voltage through a sixth resistor, the base or the gate of the PNP type transistor is further connected with the terminal through a fifth resistor, the collector or the drain of the PNP type transistor is reversely connected with an external pulse signal through a first diode, and the common connection point of the sampling resistor and the terminal is a sampling node of the sampling branch, the voltage signal of the sampling node is smaller than the power supply voltage; the sampling resistor, the third resistor, the fourth resistor and the NPN type transistor form a sampling branch circuit, and the fifth resistor, the sixth resistor, the first diode of the PNP type transistor and an external pulse signal form a trigger branch circuit.

3. The sampling circuit for amperometric speed sensor according to claim 1, comprising an NPN type transistor and a PNP type transistor, wherein the emitter or the source of the NPN type transistor is grounded through a sampling resistor, the collector or the drain of the NPN type transistor is connected to a terminal, the base or the gate of the NPN type transistor is connected to the emitter or the source of the NPN type transistor through a fourth resistor, the base or the gate of the NPN type transistor is further connected to the collector or the drain of the PNP type transistor through a third resistor, the emitter or the source of the PNP type transistor is connected to a supply voltage, the base or the gate of the PNP type transistor is connected to the supply voltage through a sixth resistor, the base or the gate of the PNP type transistor is further connected to the terminal through a fifth resistor, and the collector or the drain of the PNP type transistor is reversely connected to an external pulse signal through a first diode, a common connection point of the sampling resistor and an emitter or a source of the NPN transistor is a sampling node of the sampling branch, and a voltage signal of the sampling node is smaller than the power supply voltage; the sampling resistor, the third resistor, the fourth resistor and the NPN type transistor form a sampling branch circuit, and the fifth resistor, the sixth resistor, the PNP type transistor, the first diode and an external pulse signal form a trigger branch circuit.

4. A sampling circuit for a amperometric speed sensor according to claim 2 or 3, wherein an electrostatic discharge capacitor is connected between said terminal and ground.

5. A sampling circuit for a current mode speed sensor according to claim 2 or 3, wherein the sampling resistor is a single resistor, a series resistor, a parallel resistor or a series-parallel resistor.

6. A sampling circuit for a current mode speed sensor according to claim 2 or 3, wherein the common intersection of the sampling resistor and the terminal is connected to one input of a comparator through a filter circuit, the other input of the comparator is connected to a reference voltage signal, and the output of the comparator is connected to the I/O interface of a microprocessor; the sampling resistor samples a current signal at the output end of the current type speed sensor and converts the current signal into a voltage signal, the voltage signal is output to the comparator through the filter circuit, and the comparator compares the voltage signals at the two input ends and outputs the voltage signals to the microprocessor.

7. A sampling circuit for a current mode speed sensor according to claim 2 or 3, wherein the common intersection connection of the sampling resistor and the terminal is connected to an I/O interface of a microprocessor through a filter circuit; the sampling resistor samples a current signal at the output end of the current type speed sensor and converts the current signal into a voltage signal which is output to the microprocessor through the filter circuit.

8. A sampling circuit for a current mode speed sensor according to claim 2 or claim 3, wherein the anode terminal of the first diode is connected to a microprocessor which outputs an external pulse signal when the output of the current mode speed sensor is back to normal with the power supply.

9. A sampling circuit for a current mode speed sensor according to claim 2 or 3, wherein the NPN transistor is a bipolar transistor or a field effect transistor.

10. A sampling circuit for a current mode speed sensor according to claim 2 or 3, wherein the PNP transistor is a bipolar transistor or a field effect transistor.