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AD9914: no locking PLL and "PLL lock detected" without external clock

Question asked by RedstoneTTL on Dec 16, 2016
Latest reply on Jan 12, 2017 by RedstoneTTL

Hello!

 

When testing out a AD9914 development board the following strang thing happend:

I programmed the PLL for 30 MHZ input signal and multiplier 80. Without applying the external 30MHz clock signal (generated by a Agilent device) the green "PLL locked"-signal showed up. There was no output and no locked PLL (obvious). When reading the boards status i always got back that the PLL is not enabled.

The "control function register 3" always has the status 00 00 19 1C even if i try to write the code 00 04 19 1C in the debug tab it seem like the device is not willing to accept this. This also happens when the 30MHz generator is providing a signal.

 

Can anybody help me with that problem? The board was still working some days ago, only the setup at the DAC output and the power source (lab power supply) changed.

 

Thanks!

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