AD9578 problem

Dear Steve,

I now have a lot of experience with the AD9578, however I have a programming problem:

The device sometimes fails to lock properly ( unstable frequency a few kHz low) after repeating a programming sequence with the same values. The sequence I use  is:

1/- toggle MR bit

2/- program all registers

3/- read and print all registers

The device is now locked and outputting the correct frequency

Now repeat the above sequence with exactly the same register values

The device is now in the unstable lock mode

The read back of the registers gives identical values.

Repeating the sequence always gives an incorrect lock.

This problem occurs both in rational and fractional modes.

After the master reset, should the device be in exactly the same default  state?

Note that programming after a power on reset gives a correct lock. Also programming a completely new frequency sometimes resets the stuck mode.

best regards

Cosmo Little

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