Direct AC input for six string were LED constant-current control

Direct AC input for six string were LED constant-current control

Plan 1: Direct AC input for six string were LED constant-current control

In this paper, several solutions of this scheme is the highest efficiency should be the lowest cost of scheme, circuit (figure 1). Use directly to primary side photoelectric coupler circuit back control, adjust output voltage. Relative to other traditional scheme, the scheme of less switch loss. Will the voltage fixed in CS 0.25 V, LED to six string were constant current control. IC detects FB position, the voltage minimum that string of LED fixed in 0.5 V. At this time due to the string of LED the sum total of the value is different, Vf produce pressure drop will fall in MOS tube, cause some loss. If is the general Vf points after the screening of the BIN, loss should be able to control LED within 2%, less than the general switch loss.



The scheme is the advantage of high efficiency, low cost, the disadvantage is AC input, need more research and development costs. The solution is suitable for can use the lamps of the direct input AC.

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