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BQ2057w is MOSFET Is failing

rahul kv
Prodigy 80 points
Other Parts Discussed in Thread: BQ2057, BQ2057W

HI Sir,

 I am Using Bq2057 chargemanagement circuit to charge my 7.4V/2200mA  with NTC Inbuilt Battery for my application circuit

(1) When i feed a 12V DC Adapter as a source to the bq2057 section my charge circuit gets spoiled immmediatel especially mosfet 

(2) Can you suggest me the source voltage for the same circuit 

(3) Please look for the appplication circuit let me know if any changes to be done for the finalization 

Please find the attachement of a schmematic and let me know if any changes

8176.BQ2057W.pdf

Thanks

Rahul 

  • 0
    TI__Guru**** 165886 points

    Schematic looks okay except how are you getting 7.4V without the resistor divider as described on pages 11 and 12?  To debug, I suggest the following:

    1.  Remove D100

    2.  Apply a current limited power supply (1A) providing 9V and measure the voltage across R100?  Is that the correct current?

    3.  If so, what is the voltage BAT+?

  • 0 in reply to Jeff F
    Prodigy 80 points

    Hi SIr,

    I am using 7.4V/2200mAh Battery and as per battery manufacturing  Full charge voltage (max) : 8.30V

    (1) I have Removed D 100

    (2) I have used Bench Power Supply to Power up the Board and provided Sufficient Voltage and Current through it.

    I have Connected Li Ion battery and Measured voltage across R100 i got 200mV initially.  

    Current i got 0.90909 amps(A) As per Ohm's law.

    (3) BAT Voltage i got 7.2V

    Above readings are taken after inserting the battery to the bq2057 charger circuit

    Note: In the above situation my MOSFET is Geeting too hot i think it's dissipationg more power 

    Please suggest me a solution for the above reading and exrsise what i have done in my work area

    PFA, of a file Photo Which have taken without battery.

    Thanks,

    Rahul

  • 0 in reply to rahul kv
    TI__Guru**** 165886 points

    The sense resistor you show is 0.220 ohm which should limit the current to under 0.5A if I computed correctly.  Is that sense resistor installed correctly?

  • 0 in reply to Jeff F
    Prodigy 80 points

    Hi Sir,

    I have connected 0.22E resistor Only