ADAU1701, does the RESET input have hysteresis ?

Hello,

The ADAU1701's reset pin does have some hysteresis, see https://ez.analog.com/message/7531#7531

A RC reset is generally considered acceptable. Sorry you're experiencing an intermittent startup -- some possibilities to consider:

If you're booting from a microcontroller, be sure to wait long enough for the -1701 to come out of reset before sending any serial data. One way to insure that is to have the microcontroller operate the -1701's reset line, that way it can insure sufficient time.

Board layout at the crystal and PLL are somewhat critical for startup, for example, vias in the path between the crystal and -1701 can cause problems. See https://ez.analog.com/docs/DOC-1889 and, https://ez.analog.com/message/33074#33074

Best regards,

Bob

One issue with reset we have found in our designs was the ADAU1701 coming out of reset too soon. The ADAU1701 is pretty happy at low voltages, and will happily try to self boot. If your eeprom isn't good at low voltages, it won't be ready to be communicated with. Delaying the reset with either a reset/brown out monitor, or just a larger capacitor on the reset line can alleviate that problem.

Richard

Nikola Engineering

Hi, Bob, Richard,

Thanks for your quick reply !

First I was cheking the reset and boot sequence.
It seems that there are no problems at the start-up...
But I will check the points your advised again.

If the issue is not setteled or there are other problems,
I will make new thread again.