I have an external 10,000 Hz reference signal connected to REFBB on an AD9542 but I'm having trouble getting it non-fault lock.
The reference signal has a nominal tolerance of 600 ppm which I interpret as the signal can be anywhere from 9,994 to 10,006 Hz.
According to my calculations, I think this yields a delta p of 599640 ppb [from the formula -600E-6/(1+600E-6)*1E9= -599640.2159]
This is what is programmed into the ΔTOL register for REFBB [0x092658].
IS THIS CORRECT?
In my current rig, the actual reference input is measured at 10,003 Hz (and it's not easy for me to change this) and I can not get a valid reference lock: REFBB status (0x3008) only ever reports 'fast' and 'fault'. The register is working as it reports 'los' (and sometimes both fast and slow) when the signal is removed.
I believe that the 52 MHz chip reference oscillator is good as I am able to synthesize a 10,000.00 Hz signal on the outputs.
Any suggestions greatly appreciated.