| 摘要 |
A primary-side feedback constant current power supply and a current regulating circuit. The circuit is connected to a direct current power supply, and comprises a transformer (T1), an N-type MOS tube (Q1), a power supply driving chip (U1), a first divider resistor (R2), a sampling resistor (R1) and an adjustable potentiometer (Rs). The source of the MOS tube is grounded through the sampling resistor, and the gate of the MOS tube is connected to a PWM signal output end (GATE) of the power supply driving chip. A current sampling end (CS) of the power supply driving chip is connected to the source of the MOS tube through the first divider resistor, and is grounded through the adjustable potentiometer. Through adjustment of the resistance of the adjustable potentiometer, the duty ratio of the PWM signal is changed to adjust the current output by a secondary side of the transformer. The current regulating circuit of the primary-side feedback constant current power supply can change, through adjustment of resistance of the adjustable potentiometer connected to the current sampling end of the power supply driving chip, the current output by the power supply circuit of which the output current is defined by the current sampling end. The circuit is simple and has low cost. |
