Hello all,
In a design I am working and debugging at the moment, I am using an ADC0804 in free-running mode (no uC or uP connected to it). The ADC is converting OK, however the clock frequency (which I generate using the internal schmitt trigger is well below the expected value. I connected an external RC network comprising a capacitor of 150 pF and a resistor of 10K (as actually shown in many of the applications shown in the ADC datasheet). With these values I would expect to obtain a clock frequency around 600 KHz, but I am measuring 380 KHz. I am using 200 MHz scope probes with 12 pF maximum of input capacitance. This actually affect the frequency when I measure the CLK in pin (I assume due to the probe capacitance being added to the clock capacitance)... it brings the frequency down to some 360 KHz, but still this would not explain why I am measuring a frequency half a value of what is supposed to be!
Any ideas or experiences on this?
Thanks in advance.
Pablo