🚀 go-pugleaf

Mark wrote:

> On May 5, 9:36 am, a7yvm109gf...@netzero.com wrote:
> 
>>On May 5, 7:24 am, "Phil in Melbourne" <reply@tonewsgroup> wrote:
>>
>>
>>>So I would have thought that this would be a simple problem but the more
>>>information I get the more I get confused......
>>
>>>I want to PWM a whole lot of LEDs. The current consumption of the bank of
>>>LEDs is in the order of 15 Amps, at 12V.
>>
>>>For reasons I won't go into, my only option is to use a high side mosfet.
>>
>>>I have chosen an N-channel MOSFET (IRL3803) mainly because of its huge
>>>current capability and very low on resistance of 7 milli ohms.
>>
>>>I am hoping to use PWM at a reasonably high frequency, say 20khz or higher,
>>>and I want to use an efficient MOSFET driver IC that is designed for the
>>>job.
>>
>>Why so high? If it's just for brightness control, you don't need that
>>surely?
> 
> 
> if you strobe LEDs too slow, then it causes a strobe effect if there
> is any  movement... if you scan your eye past some LED rear car lights
> you can get the strobe effect and it is very annoying... even if the
> LED is not moving, your eye is always moving
> 
> I don't know how fast you need to pulse to avoid this but a few
> hundred Hz is too slow.   5 kHz might be OK  I don't know...
> 
> At 5 kHz you might get audio interference so that is a good reason to
> go to 20 kHz.
> 
> Mark
32 frames/Sec I believe is the minimum needed to prevent strobe flash in 
the human eye.. or some figure like that.



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