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LM3492AR111DEMO: LM3492 issue

KL TAN
Prodigy 220 points
Part Number: LM3492AR111DEMO
Other Parts Discussed in Thread: LM3492, TPS92560

Hello ,

I am designing a luminaire using LM3492 to drive four strings of duris S5 white LEDs ( LED VF is 6.1V and IF is 125mA). Currently i'm implement the configure 4S4P to LM3492AR111DEMO board and at 12VAC i can get the correct PF with 0.936 and the efficiency also nearest with 81%. By the way , i also have test with 24VAC , i can't get the good power factor. I would like to ask some question,please refer to below.

1) At 24VAC ,i need to change what component to make good power factor and efficiency.

2) At 32VAC ,i need to change what component to make good power factor and efficiency.

3) Is there have any solution or suitable application can drive up 12,24,32 VAC in good power factor and efficiency beside the LM3492.

Please help to advise.

Thanks.

Regards,

Loon

  • 0
    TI__Mastermind 25500 points

    Hello Loon,

    For the case of 24VAC and 32VAC for much of the input waveform you are above the LED stack voltage so the switcher is no longer running and the only current draw is through the linears. The input current waveform will be flat. I expect that if you switch to 8S2P for 24VAC and 32VAC you will see much improvement.

    Another option is the TPS92560. It is designed for PFC, but you may be cutting its max voltage close with 32VAC input.

    Regards,

    Clint

  • 0 in reply to Clinton Jensen
    Prodigy 220 points

    Hi Clint,

    Thanks for reply, i will test it out.

    Regards,

    Loon