AnsweredAssumed Answered

AD9957 Fast Recovery Power-Down Mode

Question asked by williamchen on May 8, 2011
Latest reply on May 9, 2011 by DSB

Hello guys,

Please help me.

I'm trying to use fast recovery power down mode, but something went wrong.

Here are my procedures:


1. System CLK is set to 926.1MHz

2. Set "External Powe-Down Control" bit to "1" (CFR1, bit3)

3. DAC outputs 110MHz signal (QDUC mode).

    The sigal shows.

4. Set "External Power Down Pin" (pin 18) from low to high

    The signal disappered.

5. Delay 4mS

6. Set "External Power Down Pin" (pin 18) from high to low


After Step.6, the waveform of "External Power Down Pin" and DAC output are shown below:

The yellow signal is "External Power Down Pin"

The Green signal is DAC output

The Time Delay marked on the screen is 125.707 uS


But if I change the "External Powe-Down Control" bit to "0" (CFR1, bit3) in Step.2

And do the the test again,

The waveform is like the picture below, and the Delay is only 6.7uS.

Set the "External Powe-Down Control" bit should set AD9957 in "Fast recovery Mode", but the wake up time is longer.

Did I make any mistake?

Please help me with this issue.

Thank you in advance!



Best Wishes,

William Chen.