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problem with BQ24081 charger

hezi nistani
Prodigy 20 points
Other Parts Discussed in Thread: BQ24081, BQ24080

1881.BQ24081-schematic.pdf

 

Hello,

I'm using BQ24081 charger in my project and I can't operate the charger.

I designed the print as it showen in the datasheet but the charger is not working - with or without battery I don't  see a change on the output pin.

I attached the schema - if anyone can help I'll appreciate it.

 

 

  • 0
    TI__Guru**** 150820 points

    Try adding a 10k resistor from TS to ground.  The bq24081 requires a thermistor on TS to charge.  If this is not in your battery pack, you need to add one yourself, use a 10k resistor to defeat the TS function, or switch to the bq24080 which does not have the TS function.

  • 0 in reply to Chris Glaser
    Prodigy 20 points

    Hi Chris,

    thanks for the reply,

    I added the 10K resistor and yet - no charge is done,

    but now I see that after I put VIN (5VDC) the charger current rise up to 800mA (that is the charging current I set with RSET(1K)) only for one sec and then gose down to 0mA - and on charge cycle begins.

    Do u know what it's means ?

    what should I do?

     

     

  • 0 in reply to hezi nistani
    TI__Guru**** 150820 points

    You need to debug the circuit.  Look at Vin, BAT, and OUT with a scope and see if Vin crashes or BAT rises to 4.2V in that 1 second.  Also, you can look at the STAT outputs and see what they do--they indicate which state of charging the IC is in. 

    Did you solder this IC by hand?  A high Ohmic connection due to poor soldering may create voltage drops on IN or BAT that affect what voltage the charger is getting.