Voltage type collision detection circuit

Abstract

The invention discloses a voltage type collision detection circuit. The circuit comprises a collision signal generator, a collision signal processing circuit and a microprocessor which are connected in sequence. The collision signal processing circuit comprises a switching circuit, a voltage division circuit and a comparison circuit which are connected in sequence, the switching circuit comprisesa first resistor and a transistor, one end of the first resistor is coupled with the collision signal generator, the other end of the first resistor is coupled with a grid electrode of the transistor,the voltage division circuit comprises a second resistor and a third resistor, one end of the second resistor is coupled with a positive electrode of a first power source, and the other end of the second resistor is coupled with one end of the third resistor and a drain electrode of the transistor. The comparison circuit comprises a comparator. The normal phase end of the comparator is coupled with the other end of the second resistor, the output end of the comparator is coupled with the microprocessor, and a positive electrode of the comparator is coupled with a positive electrode of a second power source. By means of the voltage type collision detection circuit, effective turn-off of the transistor can be ensured, and potential system power losses or device damage can be avoided.

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 a trend of high-speed vehicles, non-professional drivers and dense traffic flow, which in turn causes frequent traffic accidents of vehicle-vehicle collisions and human-vehicle collisions, which makes the research on automobile collision detection circuits have very important practical significance. [0003] ACU (Airbag Control Unit, airbag control unit) is an electronic control module, which is an important part of the vehicle occupant auxiliary protection system, and is installed in the front-end area of ​​the central channel 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. Wherein, the voltage-type collision signal is...

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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