The design of this switching power supply adopts the STC12C5A60S2 microcontroller to send out the PWM pulse signal of 47 kHz, which can get command of the MOS tubes through IR2104, thus controlling the whole BUCK (A step-down conversion) and BOOST(A boost conversion) circuit. The ADC with 10 internal that comes from the MCU can detect the real-time current feedback and the voltage values, and thereby adjusting the duty cycle of the output PWM to form a closed-loop current voltage controlling system. The button can set the output current from 1A to 2A increased by 0.05A,with the error within 0.02A. The real-time output voltage and current can be displayed by LCD. According to the test,the efficiency of synchronous BUCK was 96%while the synchronous BOOST'swas 95%, which proved its function of overvoltage protection in charging.%本开关电源设计采用STC12C5A60S2单片机发生43 kHz的PWM脉冲信号，经过IR2104控制MOS管，从而控制整个BUCK（降压式变换）电路和BOOST（升压式变换）。单片机内部自带的10位ADC能通过电压电流检测，实时反馈电流和电压数值，并由此调整输出的PWM的占空比，形成电流电压闭环控制系统。按键能设置输出电流从1A到2 A，以0.05 A递增，按键设置的输出电流的误差小于0.02 A。液晶能显示实时输出电流与电压。根据测试，同步BUCK效率为96%，同步BOOST效率为95%。具有充电过压保护功能。
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