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AD9162 TX_ENABLE Functionality

Question asked by rmgnn7 on Sep 6, 2017
Latest reply on Jan 16, 2018 by saberbf

I'm working with an AD9162 device using only NCO Mode via the SPI interface.  I'm working on implementing the TX_ENABLE pin to turn on/off the DAC output (this pin is connected to an FPGA).  I have set register 0x03f to 0xc2 which I thought would turn on/off the DAC output solely based on the value provided to the TX_ENABLE pin.  It appears this is somewhat working, but I noticed a strange occurance.  At first, the DAC output is not there, then TX_ENABLE goes high and I see a sinusoid at the desired frequency - but the amplitude is smaller than expected.  Then, when I clear and set TX_ENABLE again, the sinusoid amplitude increases.  I am thinking this is related to the ability of the TX_ENABLE pin to affect the full-scale current of the DAC output.  I do not believe I am setting the bits to do this however.

 

Can someone give me a description of how to properly control the TX_ENABLE pin based on the settings in register 0x03f?  Am I setting the register correctly for my intended behavior?  Any help is appreciated!

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