Option 1: Use a single-chip microcomputer to generate a PWM wave to control the turn-on and turn-off of the switch. The duty cycle is changed according to the feedback voltage program control after the on-chip AD sampling, so that the output voltage is stabilized at the set value. The sampling of the load current on the constantan wire is input to the single-chip microcomputer after the AD on the chip. When the voltage reaches a certain value, the switch tube is turned off to form an overcurrent protection. The program is mainly implemented by software, the control algorithm is relatively complex, the speed is slow, and the stability of the output voltage is not good. If you want to realize automatic recovery, it is more complicated to realize.
Option 2: Using constant frequency pulse width modulation controller TL494, this chip can be push-pull or single-ended output, the operating frequency is 1kHz~300kHz, the output voltage can reach 40V, there is a 5V voltage reference inside, the dead time can be adjusted, the output The source-sink current of the stage can reach 200mA, and the driving ability is strong. There are two error comparators inside the chip, a voltage comparator and a current comparator. The current comparator can be used for over-current protection, and the voltage comparator can be set to closed-loop control, and the adjustment speed is fast.
