[sdiy] Will LCD backlight PWM cause audio noise?

Tom Wiltshire tom at electricdruid.net
Fri Aug 17 18:01:20 CEST 2012


Hi All,

If I control the brightness of an LCD backlight using PWM, is it likely to cause a lot of audio noise?

I was planning to have a PIC PWM channel driving a transistor to switch the backlight on and off. This could be well above audio frequencies, say 78KHz. However, it struck me that switching a high current load (30-40 mA) on and off rapidly right next to a load of sensitive audio circuits wasn't the brightest idea I'd ever had.

What do you think? Will it cause me problems or will I get away with it?

Thanks,
Tom



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