I have the EVAL-AD5933EBZ to which I have hooked a AD5934 on SCL and SDA pins to try to get data from a different chip.
For test purposes I have tried the following:
- Vpp = 2V, want to measure without external AFE.
- set to external clock, tied 16MHz to MCLK;
- RFB = 24kohm;
- RCAL = 25kohm;
- Zunknown -> a 220pF capacitor for measuring at 10kHz;
Therefore, expecting to measure around 72kohm, I get ~49kohm. If I change to a AD5933, that one seems to measure correctly.
I'm a newbie and don't know much, but is this expected to happen? I thought that if I adjust the values for registers f_start, f_incr, then I can expect to get roughly the same Z value. Can anyone give me any advice?