Analog interface circuit compatible with resistive sensor and Hall sensor

Abstract

The invention belongs to the technical field of ignition driving circuits, and particularly relates to an analog interface circuit compatible with a resistive sensor and a Hall sensor. The circuit comprises an interface circuit and a current sampling circuit, the interface circuit is connected with the current sampling circuit; the interface circuit is also connected with an external element through an AIN interface; when the external element is a resistive sensor, the analog interface circuit works in a fixed current mode, and an ADC is adopted to carry out voltage sampling on the AIN interface to obtain a voltage value of the AIN interface; when the external element is a Hall sensor, the analog interface circuit works in a Hall mode, and a current sampling circuit is adopted to carry out current sampling on the AIN interface to obtain a current value of the AIN interface; the state of the external element can be detected to assist in judging whether ignition driving is carried out or not, so that it is ensured that ignition driving is carried out under the more accurate and safer condition, and good application prospects are achieved.

Description

Technical Field

[0001] This invention belongs to the field of ignition drive circuit technology, specifically relating to an analog interface circuit compatible with resistive sensors and Hall sensors. Background Technology

[0002] With the rapid development of technology, the importance of vehicle safety is becoming increasingly prominent. Traditional airbag ignition drive circuits only have the function of driving the airbag and cannot be linked with on-board components such as seat belt buckles and seat sensors to ensure the accuracy and safety of airbag ignition drive.

[0003] Therefore, the ignition drive circuit needs an analog interface circuit that is compatible with resistive sensors and Hall sensors to detect the status of other vehicle components in order to know the specific driving status, thereby ensuring more accurate and safer ignition drive. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes an analog interface circuit compatible with resistive sensors and Hall sensors. This circuit includes: an interface circuit and a current sampling circuit; the interface circuit is connected to the current sampling circuit; the interface circuit is also connected to external components via an AIN interface.

[0005] When the external component is a resistive sensor, the analog interface circuit operates in a fixed current mode, and uses an ADC to sample the voltage of the AIN interface to obtain the voltage value of the AIN interface.

[0006] When the external component is a Hall sensor, the analog interface circuit operates in Hall mode, and uses a current sampling circuit to sample the current of the AIN interface to obtain the current value of the AIN interface.

[0007] Preferably, the interface circuit includes a low-voltage power supply VAS, a high-voltage power supply VUP, a first diode, a second diode, a first switching transistor M1, a second switching transistor M2, a first resistor R1, a second resistor R2, a first operational amplifier AMP1, and a driver transistor M3. The low-voltage power supply VAS is connected to the source of the first switching transistor M1, the high-voltage power supply VUP is connected to the source of the second switching transistor M2, the drain of the first switching transistor M1 is connected to the anode of the first diode, and the drain of the second switching transistor M2 is connected to the anode of the second diode. The first diode and the second diode are both connected to one end of the first resistor R1, one end of the second resistor R2, and the current sampling circuit. The other end of the first resistor R1 and the negative input terminal of the first operational amplifier AMP1 are grounded, and the positive input terminal of the first operational amplifier AMP1 is connected to the other end of the second resistor R2, the drain of the driver transistor M3, and the current sampling circuit. The output terminal of the first operational amplifier AMP1 is connected to the gate of the driver transistor M3, and the source of the driver transistor M3 is connected to external components through the AIN interface.

[0008] Furthermore, when the analog interface circuit is working, it selects to turn on either the low-voltage power supply VAS or the high-voltage power supply VUP.

[0009] Furthermore, the resistance value of the first resistor R1 is N times the resistance value of the second resistor R2.

[0010] Preferably, the current sampling circuit includes a third resistor R3, a fourth resistor R4, a second operational amplifier AMP2, a PMOS transistor M4, and a fifth resistor R5. One end of the third resistor R3 is connected to one end of the second resistor R2 in the interface circuit, and the other end of the third resistor R3 is connected to the negative input terminal of the second operational amplifier AMP2 and the source of the PMOS transistor M4. One end of the fourth resistor R4 is connected to the other end of the second resistor R2 in the interface circuit, and the other end of the fourth resistor R4 is connected to the positive input terminal of the second operational amplifier AMP2. The output terminal of the second operational amplifier AMP2 is connected to the gate of the PMOS transistor M4, the drain of the PMOS transistor M4 is connected to one end of the fifth resistor R5, the other end of the fifth resistor R5 is grounded, and the drain of the PMOS transistor M4 outputs the sampling voltage.

[0011] Furthermore, when the external component is a Hall sensor, the formula for calculating the current value of the AIN interface is:

[0012]

[0013] in, This indicates the current value of the AIN interface. This represents the sampling voltage output from the drain of PMOS transistor M4. , and These represent the resistance values ​​of the fifth resistor R5, the third resistor R3, and the second resistor R2 in the interface circuit, respectively.

[0014] The beneficial effects of this invention are as follows:

[0015] This invention can detect the status of external components, such as seat belt buckles and seat sensors, to help determine whether ignition should be initiated, thereby ensuring that ignition is initiated more accurately and safely. The analog interface circuit designed in this invention, which is compatible with resistive and Hall sensors, can be applied to various types of airbag ignition driver chips and has good application prospects. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the analog interface circuit structure that is compatible with resistive sensors and Hall sensors in this invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] This invention proposes an analog interface circuit compatible with both resistive and Hall sensors, such as... Figure 1 As shown, the circuit includes: an interface circuit and a current sampling circuit; the interface circuit is connected to the current sampling circuit; the interface circuit is also connected to external components through an AIN interface.

[0019] The interface circuit is used to convert the state of external components into voltage signals. In some preferred embodiments of the present invention, the interface circuit includes a low-voltage power supply VAS, a high-voltage power supply VUP, a first diode, a second diode, a first switching transistor M1, a second switching transistor M2, a first resistor R1, a second resistor R2, a first operational amplifier AMP1, and a driver transistor M3.

[0020] When the analog interface circuit is working, it selects to turn on either the low-voltage power supply VAS or the high-voltage power supply VUP. The low-voltage power supply VAS is turned on by connecting the gate of the first switching transistor M1 to the first power switching signal, and the high-voltage power supply VUP is turned on by connecting the gate of the second switching transistor M2 to the second switching signal. The choice can be made according to the application requirements.

[0021] AMP1 is an operational amplifier used to clamp the voltages across R1 and R2 to the same potential. M3 is an output current drive transistor used to drive the output current.

[0022] R1 and R2 are conversion resistors that convert current into voltage drop, where R1 = N R2, meaning the resistance of the first resistor R1 is N times the resistance of the second resistor R2. Preferably, R1 and R2 are resistors of the same size connected in series with a ratio of N:1. Because the internal bias current is small, while the interface requires a larger output current, the internal resistance needs to be larger to reduce the internal current. AMP1 clamps the voltage across R1 and R2 to be the same, at which point the ratio of the current through R1 and R2 is the inverse ratio of their resistances, which is 1:N. Therefore, the internal adjustable current I can be adjusted... bias The magnitude of the output current of the interface is controlled.

[0023] The specific connection relationship is as follows:

[0024] The low-voltage power supply VAS is connected to the source of the first switching transistor M1, and the high-voltage power supply VUP is connected to the source of the second switching transistor M2. The drain of the first switching transistor M1 is connected to the anode of the first diode, and the drain of the second switching transistor M2 is connected to the anode of the second diode. Both the first and second diodes are connected to one end of the first resistor R1, one end of the second resistor R2, and the current sampling circuit. The other end of the first resistor R1 and the negative input terminal of the first operational amplifier AMP1 are grounded. The positive input terminal of the first operational amplifier AMP1 is connected to the other end of the second resistor R2, the drain of the driving transistor M3, and the current sampling circuit. The output terminal of the first operational amplifier AMP1 is connected to the gate of the driving transistor M3, and the source of the driving transistor M3 is connected to external components through the AIN interface.

[0025] In some preferred embodiments of the present invention, the current sampling circuit includes a third resistor R3, a fourth resistor R4, a second operational amplifier AMP2, a PMOS transistor M4, and a fifth resistor R5; one end of the third resistor R3 is connected to one end of the second resistor R2 in the interface circuit, and the other end of the third resistor R3 is connected to the negative input terminal of the second operational amplifier AMP2 and the source of the PMOS transistor M4; one end of the fourth resistor R4 is connected to the other end of the second resistor R2 in the interface circuit, and the other end of the fourth resistor R4 is connected to the positive input terminal of the second operational amplifier AMP2; the output terminal of the second operational amplifier AMP2 is connected to the gate of the PMOS transistor M4, the drain of the PMOS transistor M4 is connected to one end of the fifth resistor R5, the other end of the fifth resistor R5 is grounded, and the drain of the PMOS transistor M4 outputs the sampling voltage.

[0026] R3, R4, and R5 are sampling resistors, I1 and I2 are sampling pull-down currents, and AMP2 is used to clamp the voltage of one segment of R3 and R4 to the same potential.

[0027] When the external component is a resistive sensor, the analog interface circuit operates in a fixed current mode and uses an ADC (analog-to-digital converter) to sample the voltage of the AIN interface to obtain the voltage value of the AIN interface.

[0028] The ratio of the voltage value to the fixed current value determined by the internal bias of the circuit is calculated to determine the state of the external resistive sensor. The state of the external resistive sensor is then used to determine whether to ignite, thereby ensuring more accurate and safer ignition drive.

[0029] When the external component is a Hall sensor, the analog interface circuit operates in Hall mode (fixed voltage mode). A current sampling circuit samples the current at the AIN interface to obtain its current value. At this time, the magnitude of the current output to the AIN interface can be sampled using the current sampling circuit. Where R3=R4>>R2 and I1=I2<< Therefore, the current flowing through R2 can be approximated. Approximately equal to the output current of the AIN interface .

[0030] Therefore, the formula for calculating the current value of the AIN interface is:

[0031]

[0032] in, This indicates the current value of the AIN interface. This represents the sampling voltage output from the drain of PMOS transistor M4. , and These represent the resistance values ​​of the fifth resistor R5, the third resistor R3, and the second resistor R2 in the interface circuit, respectively.

[0033] By converting the sampled output voltage using an ADC and performing calculations with the known resistance values ​​of R5, R3, and R2, the corresponding AIN interface output current can be obtained. .

[0034] The current value of the AIN interface is used to determine the status of the Hall sensor, and the ignition is determined based on the status of the external Hall sensor, thereby ensuring more accurate and safer ignition drive.

[0035] The above-described embodiments further illustrate the purpose, technical solution, and advantages of the present invention. It should be understood that the above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made to the present invention within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An analog interface circuit compatible with resistive sensors and Hall effect sensors, characterized in that, include: Interface circuit and current sampling circuit; the interface circuit is connected to the current sampling circuit; The interface circuit also connects to external components via the AIN interface; When the external component is a resistive sensor, the analog interface circuit operates in a fixed current mode, using an ADC to sample the voltage of the AIN interface to obtain the voltage value of the AIN interface; the status of the external component is determined based on the voltage value of the AIN interface. When the external component is a Hall sensor, the analog interface circuit operates in Hall mode, and uses a current sampling circuit to sample the current of the AIN interface to obtain the current value of the AIN interface; the status of the external component is determined based on the current value of the AIN interface.

2. The analog interface circuit compatible with resistive sensors and Hall sensors according to claim 1, characterized in that, The interface circuit includes a low-voltage power supply VAS, a high-voltage power supply VUP, a first diode, a second diode, a first switching transistor M1, a second switching transistor M2, a first resistor R1, a second resistor R2, a first operational amplifier AMP1, and a driver transistor M3. The low-voltage power supply VAS is connected to the source of the first switching transistor M1, the high-voltage power supply VUP is connected to the source of the second switching transistor M2, the drain of the first switching transistor M1 is connected to the anode of the first diode, and the drain of the second switching transistor M2 is connected to the anode of the second diode. The first diode and the second diode are both connected to one end of the first resistor R1, one end of the second resistor R2, and the current sampling circuit. The other end of the first resistor R1 and the negative input terminal of the first operational amplifier AMP1 are grounded, and the positive input terminal of the first operational amplifier AMP1 is connected to the other end of the second resistor R2, the drain of the driver transistor M3, and the current sampling circuit. The output terminal of the first operational amplifier AMP1 is connected to the gate of the driver transistor M3, and the source of the driver transistor M3 is connected to external components through the AIN interface.

3. The analog interface circuit compatible with resistive sensors and Hall sensors according to claim 2, characterized in that, When the analog interface circuit is working, select to turn on either the low-voltage power supply VAS or the high-voltage power supply VUP.

4. The analog interface circuit compatible with resistive sensors and Hall sensors according to claim 2, characterized in that, The resistance value of the first resistor R1 is N times the resistance value of the second resistor R2.

5. The analog interface circuit compatible with resistive sensors and Hall sensors according to claim 1, characterized in that, The current sampling circuit includes a third resistor R3, a fourth resistor R4, a second operational amplifier AMP2, a PMOS transistor M4, and a fifth resistor R5. One end of the third resistor R3 is connected to one end of the second resistor R2 in the interface circuit, and the other end of the third resistor R3 is connected to the negative input terminal of the second operational amplifier AMP2 and the source of the PMOS transistor M4. One end of the fourth resistor R4 is connected to the other end of the second resistor R2 in the interface circuit, and the other end of the fourth resistor R4 is connected to the positive input terminal of the second operational amplifier AMP2. The output terminal of the second operational amplifier AMP2 is connected to the gate of the PMOS transistor M4, and the drain of the PMOS transistor M4 is connected to one end of the fifth resistor R5. The other end of the fifth resistor R5 is grounded, and the drain of the PMOS transistor M4 outputs the sampling voltage.

6. The analog interface circuit compatible with resistive sensors and Hall sensors according to claim 5, characterized in that, When the external component is a Hall sensor, the formula for calculating the current value of the AIN interface is: ； in, This indicates the current value of the AIN interface. This represents the sampling voltage output from the drain of PMOS transistor M4. , and These represent the resistance values ​​of the fifth resistor R5, the third resistor R3, and the second resistor R2 in the interface circuit, respectively.

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