The constant current control circuit, the output end of the transformer T is connected to the rectifier circuit, wherein the input end of the transformer T is connected with a switch control circuit, the rectifier circuit is connected with the resistor R3, the emitter junction of the triode VT is connected in parallel with the resistor R3, and the set of the triode VT The electrical junction is connected in series with the light-emitting tube of the photocoupler LV, and the output end of the photocoupler LV is connected to the transformer T through a switch control circuit.
The following figure is the circuit diagram of DC or battery input, and constant current control for 6 strings of LEDs.
It uses a multi-string boost structure design, the LED pcb driver is similar to the previous one, the difference is that the AC input is changed to DC or input by the battery. Low-voltage side sensing design As long as the appropriate MOS tube is selected, the LED can be stringed in a considerable number.
Compared with the AC input scheme, the design is relatively simple. However, due to the extra boost switch, the efficiency is relatively low. The advantage of the scheme is that the design is simple, the circuit cost is low, and the disadvantage is that the efficiency is low.
It is suitable for solar cells or street lights that are input via an adapter.