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BQ24610: Charging function failed

user6051029
Prodigy 200 points

Part Number: BQ24610

After charging is enabled, that is, the CE pin is connected to VREF, and ACDRV jumps repeatedly, so does BATDRV. The waveforms are shown in Figures 1 and 2 respectively. What is the reason?

 

Fig.1: The signal ACDRV is reversed every 40ms, the high level is 12V, and the low level is 6V.

Fig.2: The signal BATDRV is reversed every 40ms, the high level is 12V, and the low level is 6V.

When ACDRV is high, BATDRV is low.

p.s. The charging voltage is 12V.

The charging current is 0.8A.

  • 0
    Prodigy 200 points

    user6051029 said:

    Part Number: BQ24610

    After charging is enabled, that is, the CE pin is connected to VREF, and ACDRV jumps repeatedly, so does BATDRV. The waveforms are shown in Figures 1 and 2 respectively. What is the reason?

     

    Fig.1

    Fig.2

  • 0 in reply to user6051029
    TI__Mastermind 24075 points

    Hi User,

       Can you re-attach all the waveforms? I am unable to see any of the attachments.

  • 0 in reply to Kedar Manishankar
    Prodigy 200 points

    Hello,

    I tried to upload the waveforms many times,but failed. The pictures were in the testbox, I can see them. But after "POST" or "Reply", I can't see anything.

    Could you analyze the problem by my descriptions?

    Fig.1: The signal ACDRV is reversed every 40ms, the high level is 12V, and the low level is 6V.()

    Fig.2: The signal BATDRV is reversed every 40ms, the high level is 12V, and the low level is 6V.()

    When ACDRV is high, BATDRV is low. PG LED blinks all the time.

    If the CE pin is low, the power supply is normal again.

    p.s. The charging voltage is 12V.

    The charging current is 0.8A.

  • 0 in reply to user6051029
    TI__Mastermind 24075 points

    Hi User,

       From the information provided it looks like the charger is cyclically entering and exiting sleep mode. Section 9.3.8 System Power Selector describes in detail the operation of ACDRV and BATDRV. Basically ACDRV and BATDRV drive PFET so -VGS is required, and they are pulled up to VCC. To turn on the PFET ACDRV-6V (6V is internal LDO) or BATDRV-6V is applied, and it is applied asynchronously i.e only one will be on at a time. In SLEEP ACDRV is pulled to VCC to keep ACFET off, disconnecting the adapter from system. BATDRV stays at ACN-6V to connect the battery to the system. 

    Please check if you have a current limit on your power supply, as currently it looks like your power supply is not enough to supply input power requirements, causing the input voltage to start to droop and eventually hitting this SLEEP threshold (here ACDRV will switch to BATDRV). Once BATDRV turns on and there is essentially no load on the input power supply, the voltage of power supply can rise back to its set value causing BATDRV to then switch back over to ACDRV and this happens cyclically.

    Does this explanation make sense?

  • 0 in reply to Kedar Manishankar
    TI__Mastermind 24075 points

    This also confirms why when CE is low, disabling chargewhich is essentially the same condition of no load lets the power supply stay at its set voltage. You can also include VCC and SRN on your oscilloscope capture with ACDRV and BATDRV to better observe if the cyclic behavior is explaining like I explained.

  • 0 in reply to Kedar Manishankar
    Prodigy 200 points

    Hi，

    Thank you very much! I see the reason you explained，but I don't konw how to solve it. I'm sorry.

    (1) What is "input power requirements"?  I have no current limit. Whether the voltage is too low(The charging voltage I set is 12V), should I boost voltage?

    (2)What is the SLEEP threshold? 200mV? It happens cyclically because of the 200mV?

    (3)The precharge current I set is 0.08A, something wrong? Section 9.3.5, datasheet shows that the minimum precharge/termination current is clamped to be around 125mA. This configuration is OK or not.

    Please answer the above questions.

    Thanks again!

    Best regards!

  • 0 in reply to user6051029
    TI__Mastermind 24075 points

    Hi,

       1) Input power is referring to your power source used to supply VCC. It looks like the power is not enough to supply the input current and input voltage, causing the input voltage to droop (there is no input voltage regulation loop on BQ24610). When the voltage starts to droop it will hit the SLEEP (VCC-SRN spec) threshold causing ACDRV to switch over to BATDRV.

      2) Here is the SLEEP specification:

     

    Once you hit the SLEEP condition adapter is disconnected by turning off ACDRV. As there is no load on your input power supply the voltage can go back up to the setpoint, and satisfies SLEEP hysteresis  to exit sleep so BATDRV will switch back to ACDRV which is the cyclic effect as this will be repeating.

    It is possible that you also just don't have enough headroom between VCC and battery voltage, as this is a buck charger and requires input voltage higher than battery voltage to charge. You can refer to section 11 Power Supply Recommendations for information on valid VCC ranges for your battery voltage.

    3) This is not an issue as the precharge current will be clamped at 125mA if you trued to set it lower and doesn't affect what you are currently observing.