RTC_RESET_B release on i.MX8MQ

[mmovsisyan]

Hello,

In the datasheet for i.MX8MQ section 3.2.1 Power-up sequence, the following requirements is specified in step 3:

• RTC_RESET_B release (after 32K clock stable and before POR_B release, no constraint with any
other power supplies)

My questions are as follows:

1) What does "after 32K clock stable and before POR_B release, no constraint with any
other power supplies" mean? Does it say that the signal should be released after a certain number of clock cycles? POR_B release is the last step in the sequence, so it makes sense that RTC_RESET_B must be released before that. How about the last part - "no constraint with any other power supplies.

2) What controls RTC_RESET_B release timing to ensure that it is released after Step 2 (Turn on VDD_SNVS) and Step 4 (Turn on VDD_SOC and VDDA_0P9)?

Thank you

[Yuri · Accepted solution]

@mmovsisyan 
Hello,

   32K clock stable means, that the clock signal voltage is proper, frequency
is in allowed range. RTC_RESET_B release can occur in any time between
turning on of both NVCC_SNVS, VDD_SNVS and POR_B release.

Regards,
Yuri.