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Can MMPF0100F0AEP VGEN6 supplies to VIN1?

Question asked by Satoshi Shimoda on Jun 30, 2015
Latest reply on Jul 1, 2015 by Satoshi Shimoda

Hi community,

 

I have a question about MMPF100F0AEP.

Actually, our partner consider using MMPF0100F0AEP VGEN6 (3.3V) for VGEN1 supply.

I think VGEN6 output voltage accuracy (+-3%) is good to supply VGEN1 (up to 3.40V input) since 3.3V * 103% = 3.399V.

And I think there is no timing issue since VGEN6 turn-on time is up to 500 us, it is sufficient to supply VGEN1 (SEQ=9) from VGEN6 (SEQ=8).

 

However, I have concern about start-up overshoot.

VGEN6's start-up overshoot(max) is 2.0%, so in worst case, VGEN6 voltage will be 3.3V * 103%(voltage accuracy) * 102% (start-up overshoot) = 3.47V.

It exceeds VIN1 input voltage (up to 3.4V).

 

On the other hand, in the case of SW4 which is used for VIN1 supply on SABRE-SD, it also exceeds VIN1 input voltage in worst case as following.

3.15V * 106% (in PWM mode) + 66mV (start-up overshoot) = 3.405V

 

So I'm confused by these calculation.

 

 

[Question]

Can we use VGEN6 to supply VIN1?

How should we judge whether each MMPF0100F0AEP output can supply to VIN1 or not?

 

 

Best Regards,

Satoshi Shimoda

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