AD931 Calibration Questions

1. How long does it take for BPLL to lock?

2. In register 0x244, what can cause 'calibration valid' not to be set, even though we see the 'calibration done' bit set?

  • 1. BBPLL lock time is maximum 25usec.

    2. The bit is the CP calibration valid bit.

    This bit clears if the charge pump calibration enable bit in Register 0x23D, Bit D2 goes low or if the force charge pump calibration bit in Register 0x23D, Bit D3 goes high.  You can check bit D5 of 0x244 register to ensure the CP calibration is completed successfully or not.