PMID pin on switching charger

[ljy4468]

Hi all

I have a question about PMID pin,

Please see below datasheet,
https://www.fairchildsemi.com/ds/FA/FAN5400.pdf

and there is PMID pin on chip.
Datasheet says it's a power input pin but i don't know where this pin is used for.

Thanks in advance.

 

[crutschow]

The table on page 4 states that the pin is used to bypass (decouple) some of the input circuitry and thus requires a capacitor to power-ground for that purpose.

 

[ljy4468]

The table on page 4 states that the pin is used to bypass (decouple) some of the input circuitry and thus requires a capacitor to power-ground for that purpose.

Thanks for your answer,

but What i wonder is what kind of circuitry is connected to PMID pin in switching charger application?
Please give me an advice, thanks.

 

[crutschow]

Just a capacitor to ground, as stated.

 

[ljy4468]

Hi crutschow,

THanks for your answer,

So, you mean that PMID is pin-outed just for VBUS bypass purpose?

Then is there any differences between cin1 and cin2? because input vbus always comes from VBUS Pin. (please see figure 3)
is there any special purpose of 'double' bypass with cin1 and cin2?

Thanks in advance.

 

[crutschow]

...............................
So, you mean that PMID is pin-outed just for VBUS bypass purpose?

Then is there any differences between cin1 and cin2? because input vbus always comes from VBUS Pin. (please see figure 3)
is there any special purpose of 'double' bypass with cin1 and cin2?

You can see the difference. Cin2 is filtering a different point than Cin1. Cin2 is filtering/smoothing an internal signal, not VBUS.