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BQ24075RGTT not charging

pranavp
Prodigy 140 points

Hi,

I am having trouble with battery charging (BQ24075RGTT). Everything else is working. when i connect battery system is powered through battery and when i connect wall adapter system is powered through adapter. Only battery is not charging, below is the schematic i am using. ILM & ISET are both connected to ground through 1.5k resistor. I also tried grounding TS pin through 10k resistor but it also didn't worked.

It seems for some reason charging is completely off. While chip is powered through wall ac adapter charge led blinks for a second and turn off when every battery is connected.

I would really appreciate any help.

Thanks

  • 0
    TI__Mastermind 32350 points

    Hi

     

    Please compare your schematic with our EVM. What is going on with your CE, SYSOFF, EN1 and 2?it hard to see from your schematic. Can you please send some wave forms to look at (especially at VBAT)? Did you tried to charge the battery using a power supply to make sure the internal protection circuit of the battery does not interfere the charging of the battery?

     

     

    Thanks,

    Tahar

  • 0 in reply to Tahar Allag
    TI__Mastermind 31120 points

    Raise your input voltage.  The OUT is probably dropping to the DPPM threshold, 4.3V (by the system load or by some charging) and reducing charge current

  • 0 in reply to Charles Mauney
    Prodigy 140 points

    hi

    i tried with 70-80% charged battery it didn't worked.

    CE, SYSOFF, EN1 connected to ground

    EN2 connected to high.

    vbat voltage @ 4.8V input, when battery not connected: jumping between 0.44 to 1.9v

    vbat voltage @ 4.8V input, when battery connected: 3.82v

    vbat voltage @ 6V input, when battery not connected: jumping between 0.44 to 1.9v

    vbat voltage @ 6V input, when battery connected: 3.82v

    as in the EVM schematic i tried grounding the TS pin with 10k but it didn't worked. tried  the other configuration (voltage divider) at TS pin it also didn't helped.

    please see my circuit is exactly similar to the circuit in datasheet

    i would really appreciate any help

    thanks

  • 0 in reply to pranavp
    TI__Mastermind 32350 points

    Hi Pareek,

     

    I double checked your circuit with our EVM. It looks fine to me...

     

    Try to play with the EN pins and see that changes anything. As Charles mentioned, what is your input voltage and can you increase it and see if Vbat increases above 3.82? Also verify Vout vs. Vbat as in figure 14 on the datasheet? Is there any power going from input to output/bat?   

      

     

    Thanks!

    Tahar

  • 0 in reply to Tahar Allag
    Prodigy 140 points

    Hi Tahar,

    I tried what you advised but it didn't worked.

    My EN1 connected to ground and EN2 is connected to high.

    at 4.8V input, battery voltage is 3.82v

    at 6V input, battery voltage is 3.82v

    rest of the chip is working perfectly only there is issue with charging. it never charges the battery. moreover the 3.82v is the battery voltage

    I have also tried using BQ24075TRGTR it also have charging issues. what i am doing wrong?

    Thanks

  • 0 in reply to pranavp
    TI__Mastermind 32350 points

    The Pranav,

     

    Your circuit looks fine to me…Can you please double check your layout and send me the voltage level of all the pins. I think the issues is on the battery detect, are you getting into the battery detection mode? Did you try to charge the battery using external power supply?    

     

    Thanks!

    Tahar