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Regarding the time it takes for the AD9780 to stabilize DCOP and DCON after reset release.

Category: Hardware
Product Number: AD9780

Please let me know if you know about the following two questions, because I could not solve them by checking the datasheet.

(1) How long does it take at minimum for the DCOP/DCON outputs to stabilize after the RESET signal of the AD9780 is set to Low (RESET released)?

In the past QA "AD9780_DCO_P/N response time," I read that 50ns or more is required, but when I observed it with an oscilloscope, it took about 3.0us until it was biased as shown below, and it appears that 6.4us or more is needed until LVDS is output. (The waveforms were observed using a passive probe on the differential DCOP/DCON signals.)

However, at 6.4us, the DCOP/DCON swing is only about 220mV, and after waiting about 1ms, the DCOP/DCON swing is about 360mV.
The oscilloscope waveform shows the RESET signal Low after the RESET signal is held High for more than 50ms.

Immediately after setting the reset signal Low

  Immediately after setting the reset signal Low

1 ms after the reset signal is set Low

  1ms after the reset signal is set Low

2) What is the minimum pulse width required to make the RESET signal High on the AD9780?
We observed the output of DCOP/DCON with an oscilloscope when the pulse width of the RESET signal was set to 50ns, and found that the output was unstable until 2.3us after the reset was released, as shown below.

High pulse width of reset signal is 50ns

  High pulse width of reset signal is 50ns

Enlarged view of the high pulse width of the reset signal of 50 ns

  Enlarged view of the high pulse width of the reset signal of 50ns

Thank you in advance.

Shirato