AVR-Chat

On Tue, 21 Aug 2012 12:59:01 Cat C wrote:

> So how is something "ending" in an RC, using a FET as a high
> voltage switch better than a rail to rail buffer/amplifier that
> offers high/known impedance to an RC placed before it, and low
> impedance to the unknown load after it?

More complicated. Another IC. More space. More expensive.
A FET would only have to shunt at most a couple of milliamps.

Compensating for the load impedance is fairly straight-forward,
requiring only a small capacitor, 2 resistors and an ADC input on
the AVR.

The trade-off is the "ripple" and the response time. For LED
lighting, a small ripple is not important in most applications.

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