Asus N76VB identifying 'A5 GNA'

[likewise]

Hello all,

On my Asus N76NV I am suspecting a bad MOSFET (near-zero drain-source resistance) but cannot identify the part 100%.

The part is marked:
A5 GNA (sure)
GP0108 (not sure)

See photo in attachment.

This is the RBFET that matches the TI BQ24725A reference design.

Motherboard rev. 2.0.

Laptop only ran on remaining battery charge, did not charge, did not power-up without battery. It did power-up when I put 19V on the drain of this MOSFET.

ACOK=2.87V
ACDET=2.57V

I would like to find a proper replacement locally (.eu / .nl), any help appreciated to identify and find a replacement!

edit: might be PJ8804 according to the silk screen, I am interpreting this right?

Thanks all!

[kotnatan]

Re: Asus N76VB identifying 'A5 GNA'

1 - pq8806 - n-mosfet p0903bea
2 - pq8807 - n-mosfet p0903bea

[highpulse]

Re: Asus N76VB identifying 'A5 GNA'

well before adding mosfets , simple remove both , if its the front dc jack fets . and with them removed , chek they gates they shoulb be 19 volts . if its not , then bypass them all to see if there is short after the fets !!! if there is a short on the 19 volts line , the first fets will cut off power to flow

[and555]

Re: Asus N76VB identifying 'A5 GNA'

The part is marked:
A5 GNA (sure)
GP0108 (not sure)

This is P-Channel mosfet, replace with AON7403.

[and555]

Re: Asus N76VB identifying 'A5 GNA'

1 - pq8806 - n-mosfet p0903bea
2 - pq8807 - n-mosfet p0903bea

you say it's N-mosfet based on boardview, right ? did you ever measure it? It's P-Channel mosfet.

[likewise]

Re: Asus N76VB identifying 'A5 GNA'

you say it's N-mosfet based on boardview, right ? did you ever measure it? It's P-Channel mosfet.

How can we find out without desoldering?

How would the (schematic) design differ from the bq24725a reference design, where the datasheets specifically mentions it drives N-channel FETs ACFET and RBFET?

Can someone explain why there are two identical MOSFETs placed with a common source, in opposite directions? I'm trying to understand how this design works.

Thanks, would like to clear up what is the correct part.

[kotnatan]

Re: Asus N76VB identifying 'A5 GNA'

1 - pq8806 - n-mosfet p0903bea
2 - pq8807 - n-mosfet p0903bea

sorry
p- mosfet

[likewise]

Re: Asus N76VB identifying 'A5 GNA'

sorry
p- mosfet

I am confused. P0903BEA shows as an N-channel enhancement MOSFET from this datasheet:

[kotnatan]

Re: Asus N76VB identifying 'A5 GNA'

this is what shows ASUS N76VB (60NB0130-MB1030) REV 2.0 - BoardView

[likewise]

Re: Asus N76VB identifying 'A5 GNA'

this is what shows ASUS N76VB (60NB0130-MB1030) REV 2.0 - BoardView

In your screenshot there is "N-MOSFET" in front of "P0903BEA".

Also, the datasheet of P0903BEA mentions "N-channel MOSFET".

Could it be the confusion is from the "P" in the part name (P0903BEA)?

[likewise]

Re: Asus N76VB identifying 'A5 GNA'

you say it's N-mosfet based on boardview, right ? did you ever measure it? It's P-Channel mosfet.

But what part number is on the board?

If it's a P0903BEA MOSFET, why do you think it is a P-channel MOSFET?

If it's a different MOSFET, do you know what kind it is?

How did you measure the P vs N MOSFET characteristic?

I am not a laptop expert, but I do have some EE background.

[kotnatan]

Re: Asus N76VB identifying 'A5 GNA'

A5 GNA = A5 GND
marking significant "A5" P0903BEA. Everything else - the date, lot, ...
N-MOSFET P0903BEA - AON7408 & FDMC8884

[trebo]

Re: Asus N76VB identifying 'A5 GNA'

[likewise]

Re: Asus N76VB identifying 'A5 GNA'

A5 GNA = A5 GND
marking significant "A5" P0903BEA. Everything else - the date, lot, ...
N-MOSFET P0903BEA - AON7408 & FDMC8884

Thanks. I have two remaining questions:

1) Where can I find that A5 means P0903BEA?

2) In posting #7 you mentioned "p- mosfet", this confused me.

So we agree this is an N-channel MOSFET?

Thanks all! Great help here.

[kotnatan]

Re: Asus N76VB identifying 'A5 GNA'

an example of the circuit

[likewise]

Re: Asus N76VB identifying 'A5 GNA'

I already posted this datasheet in post #8?

This does not answer my question though... How can I tell it is this part?

Thanks.

[and555]

Re: Asus N76VB identifying 'A5 GNA'

P0903BEA is exactly N mosfet.
A5 GNA is exactly P mosfet.

on the boardview of Asus N76VB, the location this "A5 GNA" on the boardview indicate P0903BEA.

but actually, A5 GNA is P mosfet (kotnatan already confirm it on post 7).
so, likewise: you can replace it with AON7403.

[likewise]

Re: Asus N76VB identifying 'A5 GNA'

I do not understand why you guys think the A5 GNA is a P-channel MOSFET. I have not seen any evidence in this thread. On the contrary the BQ charger IC datasheet specifically mentions it drives N-channel type ACFET and RBFET.

I have therefore replaced the 2nd jack (RBFET) with a Microchip MCP87130T-U/LC MOSFET, N-CH, 25V, 54A, 8PDFN.

Laptop works again.

My problem is solved, some of my questions in this thread remain valid.

Regards, Leon

[likewise]

Re: Asus N76VB identifying 'A5 GNA'

an example of the circuit

That's an N-channel symbol it seems to me. I do not understand why it is depletion though.

[lining]

Re: Asus N76VB identifying 'A5 GNA'

same confusion with my problem.... I have bad A5 GNA 3ROG05 mosfet on Asus ROG G551 and I don't know it's N or P channel mosfet....bad adapter made the mosfet to be shorted. I have tried to replace with a5 GND which is N channel and the problem it's still the same, working only on battery charge but it's not charging