• State
  • Locked Locked
  • Replies 8 replies
  • Subscribers 64 subscribers
  • Views 1861 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ24210 drains 80mA from battery without any load

Sergey Vladimirov
Expert 1300 points
Other Parts Discussed in Thread: BQ24210, TPS2115A, TPS2115

hi,

Im using BQ24210 together with power muxer to charge battery from USB and solar power.

However I found out that when both sources of power are disconnected and the only thing I have connected to battery is the BQ24210 it drains 80mA (no system load is connected).

Anybody has an idea on why it drains so much power? And how I can eliminate this problem?

Thanks!

  • 0
    Expert 1300 points

    There is actually a second problem with this schematic - when I connect Solar power (4.6V) on the output of TPS2115A I only get 0.4V... ideas?

  • 0 in reply to Sergey Vladimirov
    TI__Guru**** 166996 points

    Regarding the 80mA, the bq24210 will operate in Load Mode, where current flows from the battery to a load presumed by on VBUS, when a battery is attached but no input supply is attached.  Is it possible that the TPS2115A is loading the VBUS pin?  If you disconnect the TPS2115A from the charging, do you still see a load?

    Regarding the solar panel collapse, the bq24210 will try to pull as much current from the solar panel as possible until the voltage at VBUS drops to 3.65V (since you have VDPM tied to GND).  Then it will scale back the charging current in order to prevent the supply from collapsing.  If there is an extraneous 80mA load also pulling current, is it possible that the panel is collapsing? 

    I suggest that you disconnect the TPS2115 and the bq24210 and power each independently from power supplies until you find the 80mA load (perhaps a bad solder joint?).  I also suggest that you characterize your solar panel and confirm how much current it can provide at 3.65V and the lux available.

  • 0 in reply to Jeff F
    Expert 1300 points

    Hi Jeff, you are right indeed if I disconnect TPS2115A then there is no 80mA load anymore. So why does TPS2115A takes 80mA and how can we fight that?

    Solar panel is 5V panel producing up to 120mA, and today it was a perfect sunny weather, so I expect it to produce around 105-115mA. Originally I was thinking that BQ24210 would take 100mA to charge 1000mAh LIIon battery in 10 hours. Im not sure how much actually BQ draws, but indeed if TPS takes 80mA then solar panel collapses...

  • 0 in reply to Sergey Vladimirov
    TI__Guru**** 166996 points

    The TPS2115A should not draw 80mA on its own.  I suspect a connection or soldering problem.

    Regarding the panel, what is the MPP of the panel?  If higher than 3.65V, then you might want to change the VPDM connection in order to get the maximum power from the panel. 

  • 0 in reply to Jeff F
    Expert 1300 points

    I have 5 boards produced in the factory, all have same problem, so that would be weird. Is the schematic part ok?

    yup its 5v. How do you suggest to change the connection?

  • 0 in reply to Jeff F
    Expert 1300 points

    Jeff,

    I removed R5 and that resolved the 80mA drain problem. Not sure why?

    Still the problem with voltage drop remains. When I connect USB charger I see output of 4V, with solar panel its only 0.4V

  • 0 in reply to Sergey Vladimirov
    TI__Guru**** 166996 points

    R5 was 49.9ohm on OUT so 4V coming from OUT with 49.9ohm pull down is ~ 80mA.

    Have you connected a power supply directly to the bq24210?  I would lower the current limit on the power supply to the 110mA you expect from the solar panel and see if the bq24210 limits the charge current to that value or slightly less so that the power supply voltage does not collapse below 3.65V.  If so then try to solar panel attached directly to the 210.

  • 0 in reply to Jeff F
    Expert 1300 points

    Hi Jeff,

    I limited current changing R9 to 4K. I also removed R5 completely. Now I have a different problem. Whenever in sunlight both LEDs D6 and D8 light up indicating that there is a source of energy and that the battery started charging, however Im measuring current from solar panel and maximum is at 6.5mA which of course is too low to be charging the battery. Any idea what could be wrong with that?

    Thanks!