Automatic hardwired control source selection circuit

Abstract

The invention provides an automatic hardwired control source selection circuit, and relates to the technical field of automobile circuits. The automatic hardwired control source selection circuit solves the technical problems that existing circuits are high in electricity consumption and cost and poor in reliability and reaction speed. The circuit comprises a load, a first control switch, a second control switch, a first sampling end, a second sampling end, a triode, a first resistor, a second resistor, a third resistor, a first diode and a second diode. The first sampling end is connected to the base of the triode through the first resistor. The second sampling end is connected to the collector of the triode through the third resistor and the load in sequence. The base of the triode is connected to the emitter of the triode through the second resistor. The positive pole of the first diode is connected to the emitter of the triode. The negative pole of the triode is connected to the first control switch. The positive pole of the second diode is connected to the collector of the triode. The negative pole of the second diode is connected to the second control switch. The circuit is suitable for automobile circuits.

Description

technical field [0001] The invention relates to automobile circuit technology, in particular to a technology for automatic hard-wired control source selection circuit. Background technique [0002] In the automotive electronic system, the on-board ECU needs to select the circuit of the control source according to different power states. Therefore, the automotive electronic system is equipped with a hard-wired control source selection circuit, which can control the Clamp in different power states in the vehicle power supply voltage -15 feet and Clamp-30 feet are sampled, and after judging according to the sampled values, choose to switch different control sources to control the load. [0003] In the existing automotive electronic system, the hard-wired control source selection circuit requires the participation of the microprocessor, and the software completes the sampling judgment and selection switching action. This circuit has the following defects: [0004] 1) High power...

AI Technical Summary

Problems solved by technology

[0004] 1) High power consumption: When the vehicle is turned off, the Clamp-15 pin will lose power. At this time, most of the ECUs in the vehicle will enter a dormant state. Greatly increase the quiescent current of the ECU after the Clamp-15 is powered off, that is, the power consumption after the vehicle is turned off is close to the power consumption after ignition;

[0005] 2) Low reliability: The microprocessor is responsible for controlling the switching of loads, and it needs to bear software failures, chip locks and other problems. The more complex the system, the more error-prone it is;

[0006] 3) Slow response speed: The switching of the load is controlled by the microprocessor. AD sampling requires a sampling filter time of nearly 80ms to 100ms, and its response speed depends on the response speed of the software system, especially when the MCU is turned off and started. The system needs a certain amount of time to initialize or back up data, and cannot respond in time;

[0007] 4) High cost: In addition to the cost of the microprocessor itself, the processing method of the microprocessor requires additional software development costs

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