Problem with using ADC0804 to convert data as it is not working

[ehsanelahimirza]

working of adc0804

AOA and hi to all

i am using ADC0804 to convert data and use it with 89c51.
i am using it in free running mode i.e. wr rd intr are not connected to microcontroller but they are connected according to free running mode of ADC0804 data sheet.
circuit is on page#19 of data sheet.


i have tested this circuit on bread board but now when i have made PCB, no conversion i s there.

i am using 2 ADCs in my design and they are getting 2.5V DC at Vref/2 by LM336.

whats the problem there.........

thanks very much in advance

 

[rikie_rizza]

adc0804+free running mode

how you assemble the circuit? How you draw the PCB layout? Did you solder directly or using socket? Are you sure you didn't do any mistake while drawing the circuitry? No broken wire?

If you did it with breadboard then there's an assembly problem as the first suspected problem...recheck your board, try to find broken things...anything.

 

[ehsanelahimirza]

adc0804 working

i have found the solution.

i was using switch to reset the ADC but using a capacitor solved the problem