Overclocking an ADC / DAC

[BiOzZ]

I hear quite often products using "overclocked" ADCs and DACs
im guessing there SPI ADCs and DACs but what are the risks involved? a few skipped samples?
how are the maximum speeds calculated? are they undershot by allot?
how fast can you run these things?

i was always taught to find a component with 2X the specs you need not 0.5x XP

i could see this being very useful

[smashedProton]

To add to this,  how are they overclocked?   Is it just a simple matter of getting a faster crystal?  Or would that mess up the spi

[SeanB]

Faster clock, and then the other end has to be faster to match. Leads to less accuracy on an ADC and higher noise, along with increased power consumption and heat. Relies on the manufacturer being conservative with the specs, and that almost all devices are able to operate at higher clock speeds, the specs being a guaranteed minimum. Of course some may noy be capable of doing so, so you will need to either select by testing before assembly or test when assembling and grade accordingly to a specific speed grade.

[BiOzZ]

i grabbed a MCP3008 8 channel ADC and overclocked it to 6mhz with an mbed (adc was running off 5V) and i see no noticeable change in a 10khz DC offset sine wave from my scope!  (when saved as a CSV than opened in excel compared to my scopes CSV)

at 3mhz the sine wave is choppy

i want to see how high i can push this thing and maybe stick it in a case with an USB to SPI storage bridge for an 8 channel general purpose ADC for 4 channel (psudo) differential pair ADC

funzies!

[nctnico]

I guess nobody has read up on sample & hold and clock jitter.