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AD9959 Evaluation Board X1 Crystal (2400ECSXR)

Question asked by ecephys on Feb 17, 2015
Latest reply on Feb 19, 2015 by sitti

I have an evaluation board with AD9959 on it, and used to work fine with the external function generator as a reference clock.

However, when I try to use the X1 (2400ECSXR) as a reference source, I observe some bizarre behaviors:


Before, I want to clarify/confirm few things

- It seemed I don't need to populate/remove any on-board components for X1, although for X2 it is required.

- For X1, I should set the jumper setting as REF CLK mode?

- After searching through the forum, it seemed that other people don't use X1 that comes with the board, but rather use some other crystal using the X2 connections. Is X1 to be used as a reference clock source?


The behavior

- To use X1, I thought I should set the jumper setting (W11) to Crystal mode, so I did. Then, with proper power supplied to the board (3.3 V and 1.8 V through the power terminal) and connection established to computer via USB cable, the board suddenly started consuming less voltage from the power supply (the 3.3 V line, 1.8 V was not affected). I was feeding in 100 mA at 3.3 V and these were enough to drive the board before, but all the sudden the voltage level displayed on the power supply dropped down to 1.4 V. I reverted the board configurations to get back into the operating mode, but it seems the resistance of the board permanently changed.


The incident actually has happened before as well, and the problem was gone when I came back after few days (did nothing to the board, didn't touch it for few days). The same problem that I have now may be gone by leaving the board for few days, but I need to understand why and I also do not want to pause for few days.


Please help.