A voltage type collision detection circuit

Abstract

The invention discloses a voltage type collision detection circuit, comprising: a collision signal generator, a collision signal processing circuit and a microprocessor connected in sequence; the collision signal processing circuit comprises a switch circuit, a voltage divider circuit and a comparison circuit connected in sequence; The switch circuit includes: a first resistor and a transistor, one end of the first resistor is coupled to the collision signal generator, and the other end of the first resistor is coupled to the gate of the transistor; the voltage divider circuit includes: a second resistor and a third resistor, One end of the second resistor is coupled to the positive electrode of the first power supply, and the other end of the second resistor is coupled to one end of the third resistor and the drain of the transistor, respectively; the comparison circuit includes: a comparator, the non-inverting end of the comparator is connected to the first The other ends of the two resistors are coupled, the output end of the comparator is coupled to the microprocessor, and the positive electrode of the comparator is coupled to the positive electrode of the second power supply. The present invention can ensure that the transistor is effectively turned off, and avoid potential system power consumption or device damage.

Description

technical field [0001] The invention relates to the field of automobile safety, in particular to a voltage type collision detection circuit. Background technique [0002] At present, automobile traffic presents the trend of high-speed vehicles, unprofessionalization of drivers and dense traffic flow, which leads to frequent traffic accidents of vehicle-vehicle collisions and collisions between people and vehicles, which makes the research on automobile collision detection circuits of great practical significance. [0003] ACU (Airbag Control Unit, airbag control unit) is an electronic control module, which is an important part of the car occupant auxiliary protection system, and is installed in the front end area of ​​the central tunnel of the front floor of the vehicle. When the car collides, the ACU can send a collision signal to the car controller to realize the collision unlocking, fuel cut off or high voltage circuit cut off. The voltage-type collision signal is a PWM ...

AI Technical Summary

Problems solved by technology

[0005] 1. Cause damage to the device

The first reason is that the gate of Q1 is suspended, and the bandpass filter cannot completely filter out the interference, and Q1 may be turned on or off due to interference; the second reason is that the gate of Q1 is suspended, when the drain-source voltage increases to a certain value , the gate voltage will be too high, and Q1 will be turned on; the third reason is that there is a parasitic capacitance between the gate and source of Q1. When Q1 is turned off, the gate charge has no loop to release, and the charge accumulates, resulting in Q1 is broken down

[0006] 2. The output terminal of the level conversion circuit is pulled up to the power supply of the single-chip microcomputer. On the one hand, the driving ability is low, and on the other hand, the probability of failure is high.

The former is because the power supply voltage of the single-chip microcomputer is too low, and the ability to drive the load is limited; the latter is because the power supply of the car controller is provided by the battery, usually 9-16V, which needs to be converted by DCDC (Direct current to Direct current, DC to DC) The converter is the power supply of the single-chip microcomputer. When the converter fails, the battery voltage cannot be converted into the power supply voltage of the single-chip microcomputer, so the collision signal cannot be detected.

[0007] 3. The detection method is susceptible to external interference, resulting in false positives or missed negatives and other failures

[0008] 4. The first-order low-pass filter cannot completely filter out external interference

The first reason is that the filtering effect is easily affected by the system impedance and load, and the second reason is that the only way to achieve ultra-low frequencies is to use very large capacitors, which is difficult to achieve

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