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BQ25606: charging does not start, just jumps and stops immediately, and repeats this cycle with an AC/DC USB charger, adjusted for 1.2A current, but charges normally from USB port @0.4A

Ville Savolainen
Prodigy 110 points
Part Number: BQ25606

I have tried many versions already but always the same issue repeats. Charger works fine when the battery has let's say 3.76 Volts when starting charging. But if the battery is nearly empty, for example at 3V..3.2V then the charging just flashes, I checked with an USB cable current measurement tool and it seems to try every 1-2seconds to charge and current jumps quickly to 0.6A only to stop again..so it doesn't really charge. I have made my design with the Webench tool and it works when connected to normal USB port and the slow charge starts automatically without problems even with empty batts. 

I tried multiple Adapters but some work even worse, and it doesn't even try to start charging but with one samsung adapter it at least makes this above mentioned activity..if I charge batteries to 3.6V with another charger then it works

  • 0
    TI__Expert 5590 points

    Hi Ville:

    What is your battery capacity? If status is flashing, there must be something wrong. Possibility could be:

    input overvoltage, TS fault, timer fault or system overvoltage. Do you have resistors on TS pin?  

    If you send me your schematic, I can help check it up. My email address is hmao@ti.com.

    Regards,

    Hong

  • 0 in reply to Hong Mao
    Prodigy 110 points
    battery is 18650 Sony VTC5, 2600mAh high current cell.
    yes status is flashing too. I have tried already designing the board many times and never it seems to work completely..first I thought it worked as I always charged a cell that was already above 50% charged but when I finally tried with lower levels, this phenomenon revealed itself and now I am so frustrated.

    I tried to change so many compontents..ilimit resistor, ichg resistor, add capacitance to bat, to input cap etc..but nothing helps. Tried another inductor.. The only way it works is when I connect it to a computer USB output and then it charges at low current..but with normal high current adapter it just does not work if the battery voltage is relatively low.

    Input overvoltage hard to imagine as I tried with many different USB adapters.
    I have temperature resistors, as suggested in webench, with the ntc. and it seems hard to imagine problem would lie there as the behaviour starts immediately when connecting a normal 1.5-2A USB adapter, while computer port works fine.

    Sometimes it does like this: The stat pin and charging current flashes for some moments and then it finally starts the charging process. It seems like it needs to try and try and finally it might start but this needs the battery to have a higher starting voltage.
  • 0 in reply to Ville Savolainen
    TI__Expert 5590 points

    Ville:

    Could you send me your schematic with components values on it. What is the charge current you plan to set at? 1.2A? Have you tried our EVM to charge your battery? Do you have battery protection circuit attached to your battery? Can you have another battery? You may also try 18650 x 2 in parallel.

  • 0 in reply to Hong Mao
    TI__Expert 5590 points
    Hi Ville:

    I reviewed your schematic. It looks OK. Where did you connect D+/D- to? You may short D+/D- if do not use it. It seems that is battery related. Please replace the battery as I suggested and use thick and short wire connect battery to your battery to the charger. For a single 18650, I suggest you charge at lower current, e.g 1A. From your schematic, the charge current is set at higher than 2A.