hp 640 G2 charging issue

[bembeno]

hp 640 G2 when i connect charger the charging sign apear for 2 sec then its stop and the lap plugedin but not charging
the charge ic number is BQ24780
pin 1 acin = 19 v
pin 2 acp 19 v
pin3 cmsrc 19 v
pin4 acdrv 24 v
pin 5 acok 3 v
pin 6 acdrt 2.5 v
pin 7 iadp 0 v
pin 8 idchg 0 v
pin 9 imvp8 psys 0 v
pin 24 chg regen 6 v
ther is a diod its number is D60099 which there is 19 v on two legs of its legs and the leg which connected to the battery coil has 1.4 v

[mon2]

Re: hp 640 G2 charging issue

The ACDRV is good.

1) Remove all power & battery.

2) trace the ACDRV pin to the usual 2 x DCin mosfets.

3) Meter in resistance mode -> check the resistance of the same 2 x DCin mosfets.

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

[bembeno]

Re: hp 640 G2 charging issue

what about pin 7,8,9 there is jo volt on these pins

[mon2]

Re: hp 640 G2 charging issue

The VCC pin #28 on the charger IC looks low for the DC adapter voltage that is coming into the board.

Double check that part of the circuit.

[bembeno]

Re: hp 640 G2 charging issue

pin 28 = 19 volt

[bembeno]

Re: hp 640 G2 charging issue

the 2 mosfet in charging circuit the uper one has 19 on the drain 0.485 on gate and 0.485 on source and lower mosfet has 0.485 on drain and 0 on gate and 0 on source now the output volt to the charging coil is 0.485

[bembeno]

Re: hp 640 G2 charging issue

i changed the charging ic BQ24780 with BQ24780S now the output = 12 volt and now the laptop is charging thank you man

[mon2]

Re: hp 640 G2 charging issue

These charger designs are often with N-channel mosfets for the 2 x DCin. The gate needs to be ~6 volts higher than the voltage they are passing to enable.

You mentioned that ACDRV at the IC is ~24v ? This is a good voltage, yet the GATE voltage on the mosfets is ~0 v ?

Remove all power -> search for a series resistor ~4k ohms that should be between ACDRV and the GATE of the DCin mosfets.

It appears that this series resistor may be damaged or missing.

If your design is not like the reference TI datasheet then we need to know the topside markings of your mosfets. Post all of the details.

3) Meter in resistance mode -> check the resistance of the same 2 x DCin mosfets.

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Remove all power -> post these resistance measurements for a review.


Update - very good work !! (ignore this post)