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BQ24030EVM - Blinking STAT LEDs when swapping from Fast charge Mode to Termination charge mode

Carlos_Gonzalez_de_Juan
Prodigy 100 points
Other Parts Discussed in Thread: BQ24030EVM, BQ24030

Hello everyone!

I am currently developing some tests using BQ24030EVM and I have detected a strange situation when charging the battery.

I have removed R9 so as to enable the TS capability and I found in first place, when charging in Fast Charge Mode, there is no problem, STAT1 LED is ON and the current measured through a multimeter into the battery is OK.

The problem comes when the battery reaches 4,05V and BQ24030 is swapping from Fast Charge to Termination Charge. In this proccess both STATX LEDs are blinking alternatively for more than half an hour and of course, the current sunk by the battery is swapping from 50 mA (more or less) to 130 mA (more or less) and this is precisely what I want to avoid.

Is there any way to perform a clean step from Fast Charge Mode into Termination Mode?

I hope to hear from you soon!

Regards.

  • 0
    TI__Expert 7730 points

    Did you connect TS to your battery NTC after removing R9? What is your programmed charging current and do you have a system load at OUT pin? I don't expect BAT pin to sink this much current.

    STAT1/STAT2 LEDs will blink only when the IC doesn't detect the battery. Can you capture the plot of TS pin and BAT pin when STAT1/2 LEDs are blinking?

    Thanks,

    Wenjia

  • 0 in reply to Wenjia Liu
    Prodigy 100 points

    I did connect TS to my battery's NTC. My programmed charging current is programmed to be 1,125 mA in FAst Charge Mode and 112,5 mA in Termination Mode due to my Rset is 1Kohm (default value in the BQ24030EVM for R6).

    I do also have a load at OUT pin. It is just a 10 Kohm resistor as you can see in the picture.

    The point is, when the leds were blinking, current from the source were being sunk, but no steadily, it was being sunk switching from 0 to X (130 mA more o r less) at the same speed the leds were blinking so It makes me think that IC is detecting the battery is present but somehow, it is not swapping right from fast charge to termination...

    Could Rtmr be a problem?

  • 0 in reply to Carlos_Gonzalez_de_Juan
    TI__Expert 7730 points

    One possibility is because of your line resistance between BAT pin and your real battery, the IC is switching between termination and re-charge. For example, when you have 130mA current or more, the VBAT is above Vreg because of the voltage drop over the line even if the real battery voltage is below Vreg. Once this happens, the charging will be terminated and the voltage drop will be gone. As the voltage drop is gone, the VBAT will drop to the same level of the real battery so the re-charging is triggered and you will see charging current again and the same cycle went on forever. So can you capture the waveform of the voltage at the BAT pin and the charging current at the same time to check if my theory is true?

    Thanks,

    Wenjia