The core of the electronic control

The core of the electronic control unit is a single-chip microcomputer, which has high requirements for power supply. The voltage of the storage battery is unstable. High-inductance electrical appliances will generate high-frequency oscillating electromagnetic waves in the circuit when they are disconnected. The peak value can reach 280V, and the peak value of the negative pulse voltage caused by the ignition circuit can reach 50-100V Appears at a certain frequency in the system. Therefore, these issues must be considered when designing the power supply. The system stabilized power supply is shown in Figure 3-9. It can turn the unstable 24V voltage provided by the battery into a high stable voltage 4.5 ~~ 5.5V that can be used by the single-chip 80C196KC. This voltage conversion circuit uses 78XX series integrated three-terminal regulator. The output current of the three-terminal regulated power supply is 100mA ～ 3A, the voltage regulation coefficient is 0.005% ～ 0.02%, and the ripple suppression ratio is 56 ～ 68dB, which can better meet the voltage demand of the single chip microcomputer. In Figure 3-12, C1 can prevent self-excitation caused by the inductance effect caused by the long input lead. C2 is used to reduce the high frequency interference caused by the instantaneous change of load current.