[Arm-netbook] hannstar LCDs LED backlight circuit

Luke Kenneth Casson Leighton lkcl at lkcl.net
Wed Dec 10 09:25:51 GMT 2014

On Wed, Dec 10, 2014 at 7:53 AM, joem <joem at martindale-electric.co.uk> wrote:

>>  if you have one of those boards can i ask you the favour of locating
>> the white LED circuit and sending me a macro-zoom photo (both sides)
>> of that section of the board, highest resolution you can?
> Will try


> If instead you were to send a PWM signal say 1kHz
> for SY7201A then LED can be dimmed depending on
> MARK:SPACE ratio of the signal.
> :
> RC circuit not needed.

 the only reason i can think of that it's been done is that the RC
circuit can be used, at high enough frequency, to vary the current
rather than do actual PWM at coarse/low frequency.

 anyway, it's gone.


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