The choice of processor and A/D seem to be almost impossible given the information you gave.

If you want to reproduce a signal that has a duration of 10 microseconds then you will need a relatively high sample rate in order to achive any kind of faithful reproduction. Most, if not all, microcontroller A/D's are not capable of sampling fast enough give you very many data points over a 10 uSec internaval. Heck, you are lucky in most cases if you can get one sample completed in 5 to 10 uSec.

It also strange to mention that the signal frequency that you are sampling is in the 200 to 500 Hz range. Over a 10 uSec interval you are only going to see a very small portion of one cycle of the input signals in this frequency range. 500 Hz has a cycle time of 2000 uSec.

Michael Karas