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BQ24296M: BQ24296M

Yair Shuvali
Prodigy 30 points
Part Number: BQ24296M

I am using BQ24296M my calculation to support -20C +60C is

RT1= 2.72KOHM

RT2=8.33KOHM

This calculation based on battery sense resistors with the following parameters:

-20C 71.18KOHM

+60C 3KOHM

I observe that the charging persists at elevated temperatures, exceeding +60°C, without ceasing 

 

 

Pls. advice what may go wrong

  • 0
    TI__Genius 15185 points

    Hi,

    The math you've provided appears to be about right for the NTC you've provided, VTS should be approximately 44.7% of REGN at 60C so charging should cease. There is a few tests and measurements that would be helpful to figure out why charge isn't stopping.

    1. While measuring VREG, with a power supply directly decrease the voltage of VTS and measure the voltage at which it stops charging. This is to confirm there isn't any setting or issue that is gating the TS. When doing this test please measure VREG and VTS when the charging stops.

    2. If possible, please provide a waveform with of VTS when the device is meant to cease charging to ensure it is a clean signal.

    3. Please replace the NTC with a 3 kOhm resistor to check for inconsistency in the NTC's resistance. Check if charging stops with a 3 kOhm resistor in place of the NTC.

    4. Does charging stop at the -20C point?

    With these tests we may be able to round down the cause of the charge not stopping.

    Best Regards,

    Juan Ospina

  • 0 in reply to Juan Ospina
    Prodigy 30 points

    Hi Juan

    The charging stopped at -20C 

    I am conducting these tests in the chamber, making it challenging to monitor the VTS.

    Any Chans that the charger is faulty? 

    I will try to replace the NTC to 3K and repeat the test at hot temperature 

  • 0 in reply to Yair Shuvali
    TI__Genius 15185 points

    Hi Yair,

    Yair Shuvali said:
    Any Chans that the charger is faulty? 

    We can verify this IC is behaving outside of expected behavior by biasing the TS pin to the expected voltages. This should be quicker than using a temperature chamber. If charging stops when VTS is at VREGN x 0.735 or VREGN x 0.472 then we know it should behave as expected at the expected resistor values for these temperatures.

    Additionally using the 3kOhm resistor can help to verify that the correct resistance will result in the expected shutdown, since the NTC isn't being used I think you can run this test without having to wait on chamber temperature controls.

    Best Regards,

    Juan Ospina