No ACDRV - Possible faulty capacitor - Pls advise

[IamPritesh]

Please refer to the image . The board came with no charging ..I have replaced the charging IC Bq25A but symptoms are same. There is no schematic or boardview for the same. If the capacitor is faulty, how do I know which value capacitor should I use. Can I use a jumper ?


Also is ACDRV an output voltage from the Charging IC? I think it should be around 25V

If any information is missing pls let me know.
MB : CSL50/CSL52 LA-E791P

[piernov]

Re: No ACDRV - Possible faulty capacitor - Pls advise

Check second DC-in MOSFET for short between drain/source/gate, and for short to ground.

ACDRV is indeed a volatge generated by a charge pump inside charger IC and should be around 25V (DC-in voltagr +6V).

[IamPritesh]

Re: No ACDRV - Possible faulty capacitor - Pls advise

Actually the ACFET [ MTB04N03] is short between drain and source .
so which alternative mosfet can I use..? I have the following N channel mosfet in similar package

MDU2657
K03B9
FDMS0312AS
FDMS7698

[piernov]

Re: No ACDRV - Possible faulty capacitor - Pls advise

Anything that has same or higher max Vds (30V), and same or higher current rating Id.

[IamPritesh]

Re: No ACDRV - Possible faulty capacitor - Pls advise

Replaced both the mosfet still unable to resolve ACDRV voltage is only 18.5 V

[piernov]

Re: No ACDRV - Possible faulty capacitor - Pls advise

Measure exact voltage on both DC-in MOSFETs drain/source/gate.
Measure resistance to ground after second DC-in MOSFET.

[mcthr]

Re: No ACDRV - Possible faulty capacitor - Pls advise

Check current sensing resistor if its short to ground

[Sephir0th]

Re: No ACDRV - Possible faulty capacitor - Pls advise

18.5V at ACDRV means there is still a shorted DC-IN Mosfet present. I didn't noticed any other reason so far.

[mcplslg123]

Re: No ACDRV - Possible faulty capacitor - Pls advise

18.5V at ACDRV means there is still a shorted DC-IN Mosfet present. I didn't noticed any other reason so far.

No doubt about it. Bang on.