"in adc 0808/0809,
when we bias it, the EOC(7th pin) remains at 1.5V ,not at 5v. so the conversion doesn't take place. is it the specific chip problem?(i tried it in two chips)."

What does 'when we bias it' mean? What is 'biasing' and what exactly are you biasing?

It is important to note that 1.5V is not a valid output voltage for that device. Is your measurement correct? If so, are all pins connected properly (no outputs connected to power rails or other outputs, no floating inputs, etc.). Is your power supply in tolerance?


"as per theory, EOC remains high during the conversion.when conversion finished, it goes low and we hav to monitor it by polling to get the data."

Check the datasheet. EOC goes low during conversion. Do you fully understand the operation? Are you supplying it with a clock signal? That would likely cause the EOC pin to never change once a conversion is started..

Good luck.

- Lee