On 13 April 2012 00:26, Neil <picdude3@...> wrote:
> What exactly do you mean by "clamping the output"? I actually need 0.5V
> to 4.5V output, and Vdd will be 5V. But I was looking for the A/D
> feedback,etc for accuracy, since the PWM voltage output will be subject
> to variations in Vdd.
Basically I was thinking about a system where the output voltage was
limited to, say, 4.5V by means of a series resistor & precision zener
/ TL431 etc. This would then be independent of supply voltage but
subject to any temperature drift in the clamping device. The minimum
voltage would be close to zero - if you need it to be 0.5V, then you'd
need to add it in - use an opamp circuit to provide the clamping
function with a 0.5V offset.?