Can I powerup ADAU1701 without a reliable clock?

SigmaDSP & SigmaStudio joe42 Mar 17, 2014 00:00 1 replies Original on forum ↗

joe42 Question

Mar 17, 2014 00:00

It's not quite as crazy of a question as it sounds.

I have a clock source on my board I'd like to use for the ADAU1701, but the circuit providing this clock is powered up at the same time the ADAU1701, so I can't guarantee it's creating a nice stable clock when the 1701 is starting. If I apply a reset to the 1701 at some later reasonable time, can I expect the 1701 to start reliably?

I want to be sure an errant/unstable/missing clock doesn't put the 1701 in some oddball state that can't be cured by a reset.

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adau1701

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Yagami Reply

Mar 24, 2014 00:00

Hi joe42,

In my experience, this will work. You can test it using the EVAL-ADAU1701MINIZ quite nicely, since it has both a hardware reset button and a clock source switch. Follow along with this simple sequence and you can confirm the results I'm seeing:

Before powering up the board, flip the switch so that the MCLK source is set to the I2S header. However, there's nothing connected to the I2S header, so you're effectively disconnecting the ADAU1701's MCLK input pin from any signal source.

Power up the board

Wait a while

Flip the MCLK input switch to select the oscillator

Now press the reset button

After reset, you should be able to configure the ADAU1701 and get it up and running

In my experience, this works without fail. It suggests that you can simply trigger a reset after the master clock signal is present, and booting should work properly.

Hope that helps!

Thanks,

Yagami

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