the first pin vin and the other end of the third filter capacitor c 3 is grounded the first resistor r 1 and the second resistor r 2 are connected in series one end of the first resistor r 1 is connected with the fifth pin out and one end of the second resistor r 2 is grounded both a negative input end of the first voltage comparator and a positive input end of the second voltage comparator are connected between the first resistor r 1 and the second resistor r 2 the detection resistor r 11 is connected between the fifth pin out and the anode of the load end 104 the fourth resistor r 4 the fifth resistor r 5 and the adjusting resistor rx are connected in series one end of the adjusting resistor rx is grounded and one end of the fourth resistor r 4 is connected between the detection resistor r 11 and the anode of the load end 104 both a positive input end of the first voltage comparator and a negative input end of the second voltage comparator are connected between the fourth resistors r 4 and the fifth resistor r 5 an anode of.