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AD9154 Blanking State Machine Blocking DAC Outputs

Question asked by DZF on Nov 3, 2015
Latest reply on Mar 24, 2017 by larrywelchusa

I'm working with an AD9154 board, and it looks like the blanking state machine is blocking the DAC outputs: I'm reading back 0x00 from register 0x147, which according to Table 73 in the datasheet indicates that the blanking state machine (BSM) is holding the output data at midscale.

 

From what I can see in the datasheet (in Figure 73 and text on page 68), this should only happen if the TXEN0/1 signals are active or if the LMFC sync machine is in the middle of a rotation. As far as I can tell, neither of these things are true here: the sync machine is locked (register 0x03B = 0x0D), and the TXEN0/1 inputs are both being driven high after the DAC is configured. The sync machine is configured for one-shot operation (bits 3:0 of register 0x03A = 0x1) with a continuous SYSREF input.

 

Are there any other conditions that could cause the BSM to hold the output data at midscale?

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