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PWRDWN de-assert timing in POWER-UP SEQUENCE of ADV7180.

Question asked by Tamu on Aug 18, 2016
Latest reply on Aug 18, 2016 by Tamu

Hello,

 

I have a question about POWER-UP SEQUENCE of ADV7180.

My customer will use ADV7180.
The power-up sequence on his board is as follows:
1. Power up the 3.3 V supply(DVDDIO). PWRDWN pin is pulled to the 3.3V, so PWRDWN is also high at the same time.
2. After 30ms, power up the 1.8 V supplies (DVDD, PVDD, and AVDD).
3. After 300ms, pull the RESET pin high.
Please refer attached file "ADV7180_Power_UP.xlsx".

This is not hold by POWER-UP SEQUENCE of the datasheet.

 

Question:
Do we have any problem with this power-up sequence?
We think this is no problem because
- PWRDWN pin is pulled to the 3.3V DVDDIO, so it can not be reverse voltage situation.
- Also, just after PWRDWN becomes high, Reset is kept low. And after power up the 1.8 V supplies, Reset becomes high.
So we think it can not be problem.
What do you think?
If we have some problems for this power-up sequence, could you tell us what kind of problem may occur?

 

Thank you!
Best regards.

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