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BQ24160 evm 721

Natallia Holubeva1
Expert 6550 points
Other Parts Discussed in Thread: BQ24160, BQ24161B, BQ24168, BQ24161

Hello,

My customer is worried that default Charge current for Battery < 3V is 1A! Li-ion batteries are spec’d (for safety purposes) to be pre-conditioned at 100mA unil it reaches 3V. Am i missing something?

Thank you !

  • 0
    TI__Genius 13700 points

    Hello Natallia,

    When the battery voltage is below 3V the device will be in short circuit detect providing the batter 50mA to close any protection circuitry in the pack, test for a short, and precharge the battery up to the fast charge voltage threshold of 3V for the BQ24160.

  • 0 in reply to Ryan May
    TI__Expert 6550 points

    Ryan,

    Thank you very much for your help. I understand that it will draw up to 1.5A after the battery reaches 3V. My concern here is that somce computers USB ports can only source up to 500mA. If I am connecting the BQxx to it, it could reset due to exceeding port`s current limit of 500mA. Question: what is the most efficient way to limit the current?

    Tahnk you

  • 0 in reply to Natallia Holubeva1
    TI__Expert 6550 points

    I see that BQ24161/BQ24161B/BQ24168  have PSEL to limit the current. But the customer is already using bq24160. Any advice?

    Thanks a lot!

  • 0 in reply to Natallia Holubeva1
    TI__Genius 13700 points

    Hello Natlallia,

    These devices have something called Dynamic Power Management (DPM). When the charger sees the input voltage droop either due to system load current or charging current it will reduce the current used for charging to prevent the USB source from collapsing. This is discussed on Pg. 24 of the BQ24160 datasheet:

  • 0 in reply to Ryan May
    TI__Expert 6550 points

    Hello Ryan,

    My customer just received the boards and having some issues. The BQ24160 output is only at ~2.6V with 5V USB input and 100mA Load on SYS pin. Any clue what might be going on? he has 47uF//22uF on SYS ouput.

    Thank you,

    Natallia

  • 0 in reply to Natallia Holubeva1
    TI__Genius 13700 points

    Hello Natallia,

    Could your provide me some more information about what their system set up is? T

    The BQ24160 has a set of SYS and SYSmin voltages detailed on Pg. 5 of the datasheet and none of them go that low. The first way that I could see the SYS voltage being that low would be if it was in supplement mode. Do they have a battery attached?

    Do they have scope captures of input voltage and current as well as SYS voltage and current?

  • 0 in reply to Ryan May
    TI__Expert 6550 points

    Hello Ryan,

    There is no battery attached. Just the USB cable plugged to the board supplying 5VDC. How would it enter the supplement mode if the battery isnt there and no V batt isnt rising at all? Also, since it is our EVM we are talking about I dont see anything wrong... Could you confirm the following: the registers set Vsys to be 3.5 with removed battery by default? Also, do you have the EVM? I could check it myself.

    Natallia

     

  • 0 in reply to Natallia Holubeva1
    TI__Genius 13700 points

    Hello Natallia,

    As per our offline discussion please obtain more system information to help move this discussion forward.

    Please obtain scope shots of the input voltage and output voltage during start up and during steady state. There is no case that I can think of why the OUT will be 2.6V

    Also if there is no battery present it should be running through the battery detection algorithm. In the case that Vin has drooped too low the detection would not run causing there to be no voltage on the BAT pin.

  • 0 in reply to Ryan May
    TI__Expert 6550 points

    Ryan,

    Could you please do the schematics review? I will send it to you via email.

    Thanks a ton!

     

  • 0 in reply to Natallia Holubeva1
    TI__Genius 13700 points

    This was handled offline.

  • 0 in reply to Ryan May
    Prodigy 70 points

    Hi, in the bq24160 datasheet i can not find a sufficient description of the battery detection algorithm!! so please can you explain it more... thank you :)

  • 0 in reply to ayman rjab
    TI__Guru*** 143850 points

    During battery detection, IDETECT is pulled from VBAT for tDETECT to verify there is a battery. If the battery voltage remains above VDETECT for the full duration of tDETECT, a battery is determined to present and the IC enters “Charge Done”. If VBAT falls below VDETECT, a “Battery Not Present” fault is signaled and battery detection continues. The next cycle of battery detection, the bq2416xx turns on IBATSHORT for tDETECT. If VBAT rises to VDETECT, the current source is turned offand after tDETECT, the battery detection continues through another current sink cycle.

    In short, there is a push pull driver that pushes current into the BAT pin for a short time and then pulls current out of the BAT pin for s short time.  If the voltage on the BAT pin moves up and down, then it is assumed that a battery is not present. A large capacitor on BAT that doesn't discharge enough when current is being pulled from the BAT pin will fool the IC into thinking there is a battery present.