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DAC5652AEVM: Not seeing EVM output on Oscilloscope

Aditya Gaddam
Intellectual 850 points
Part Number: DAC5652AEVM
Other Parts Discussed in Thread: DAC5652A

Hello,

I'm trying to use the DAC5652A in my design. I have the EVM hooked up and am trying to generate voltages but am not seeing any output. 

As per the EVM manual, I have applied 3.3V to both VDD and AVDD. I am supplying DA0-DA9 with increasing values from 0 to 1000 and supplying a clock on WRT1. I have J1 connected to an oscilloscope.

The timing and data on the bus and clock are shown below:

I am however, seeing nothing on J1. I have tried toggling SLEEP while the data is being clocked in. If it helps, the EVM board is drawing about 80mA when I power it on and clock in data. 

What could I be missing? 

Sincerely,

Aditya

  • 0
    TI__Mastermind 18095 points

    I cannot tell how you are injecting the bits.  Verify that they are getting through to the pins of the device properly with a probe to ensure buffers are working properly and the swing is proper.  I cannot tell the details of the input pattern.  Perhaps you are injecting a low frequency ramp pattern.  If so, note the EVM is nominally configured with a transformer that will not pass DC or very low frequencies.  It will pass higher frequency AC signals.  If a low frequency output is needed, there is the option with some 0 ohm solder jumpers to bypass the transformer.

    --RJH

  • 0 in reply to RJ Hopper
    Intellectual 850 points

    Thanks for the heads up on that!

    I removed the transformer and jumpered the output to the SMA connector. I am only seeing a voltage swing of about 55mV instead of about 1Vpp like the datasheet says but I can change the load resistor to increase this (Was able to change the load resistor on IOUTA to 500ohm to make the swing around 550mV). At least for now, I am seeing an actual output. 

  • 0 in reply to Aditya Gaddam
    TI__Mastermind 18095 points

    This will be addressed in the subsequent post.  --RJH