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BQ24650: Not charging the battery

Ehsan Kazemi
Prodigy 170 points
Part Number: BQ24650

I'm trying to design a circuit based on BQ24650 IC for charging single cell Li-ION battery with maximum 2 amp.

The solar panel I will use has the following characteristics:

Voc = 7.2 v

Nominal Voltage = 6 v

Open Circuit Current = 1 A

For now, I'm using a work bench power supply set at 7 volt and 1 amp to simulate the solar panel.

I checked the voltage on all pins of the IC. Some are normal as indicates the datasheet but some seem strange i.e. the HIDRV pin.

here are the voltage value of all pins:

Vcc = 7 V
MPPSET = 1.4 V
STAT1 = 24 mV
TS = 1.95 V
STAT2 = 4.77 V
VREF  = 3.31 V
TERM_EN = 3.31 V
VFB  = 1.95 V 
SRN  = 3.91 V
SRP  = 3.91 V
REGN = 7.41
LODRV = 179 mV
PH = 3.88 V
HIDRV = 3.72 V
BTST = 3.28 V
All the components and their values was chosen based on the data sheet, evaluation board document and the calculator provided by TI.
I attached the schematic and the pcb layout. 
I will appreciate if you could help me to find the problem(s).

  • 0
    TI__Mastermind 20300 points

    Could you please send the schematic again?

    What is the end equipment/application for this?

    REGN should be regulated at 6V. From your measurement, it is higher than your VCC. There is something wrong here. Have you tried to test on another IC?

  • 0 in reply to Jing Zou
    Prodigy 170 points

    hi Jing Zou;

    thank you for your reply.

    I have attached the schematic and the pcb layout. But just in case I attach them again.

    Jing Zou said:
    What is the end equipment/application for this?

    This will be a power bank charged with solar panel and simultaneously charge a phone via USB.

    Jing Zou said:
    Have you tried to test on another IC?

    No. I have not test the circuit with another IC. But before that, would you please verify the circuit and the values of the components (caps and resistors)?. If all other components are chosen correctly, I confidently can solder new IC and other components on another pcb.

    Thank you again for your time.

    best regards.

  • 0 in reply to Jing Zou
    Prodigy 170 points
    hi Jing Zou;

    As you suggested, I made another board with new IC and new other components. Unfortunately, the voltage on all the pins are the same as before. for example, the voltage on the REGN pin is still 7.41 volts and the circuit doesn't charge the battery.

    What do you suggest now?

    thank you again.
    best regards
    Ehsan Kazemi
  • 0 in reply to Jing Zou
    Prodigy 170 points
    hi Jing Zou;

    Thank you for your help. Finally the circuit is working. The problem was a silly mistake of mine. I had installed the D2 diode incorrectly polarity-wise.