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BQ24630EVM: 7-cell type battery control IC

Jonathan Navor
Genius 9235 points
Part Number: BQ24630EVM
Other Parts Discussed in Thread: BQ24630

Hi Team,

Good day! I'm posting this in behalf of the customer. Could you please help to check. 


They bought a BQ24630 development board and drew a circuit diagram.
The circuit contents when the VBAT output is 8.4V and the output current is 40mA are
KIndly review the circuit if correct when VBAT output of 8.4V and output current of 40mA.

Attached schematic. 

BQ24630_EVA.pdf

Thank you for your support.

Best regards,

Jonathan

  • 0
    TI__Mastermind 33075 points

    Dear Jonathan,

    My schematic review is as follows:

    1. I do not see any pullup of the CE pin. In order to enable charge the CE pin needs to be driven HIGH.

    2. Do they intend to use a thermistor with their battery back? If so, make sure it is programmed correctly for the desired temperature range. If not, please bias the TS pin at the correct voltage. See Section 8.3.18 of the datasheet for details.

    3. Confirming 960 mA input current limit.

    4. I calculated the charge current as 410 mA, not 40 mA. The calculation is 3.3*120/(100+120)/20/.22.

    5. I calculated the termination current as 13.6 mA. Please keep in mind that with a termination current of 13.6 mA and sense resistor of 0.22 Ohms, the sense voltage is approximately 3 mV. The accuracy of the termination at this voltage is between +/-45% and +/-25%.

    6. The battery regulation voltage is 1.8*(1+360/100) or 8.28 V.

    7. Confirming charge timer of 2.33 hours.

    8. TP1 in the upper right corner is labeled as VBAT, this is the system node. Do you intend to have a system load?

    Thanks,

    Mike Emanuel

    Please click "Resolved" if this answered your question.

  • 0
    Prodigy 140 points


    Dear Mike and Jonathan

    Thanks for the confirmation.
    I have modified the schematic from what you advised, so
    I apologize for the inconvenience, and thank you for your understanding.

    It is my lack of understanding, but when TS pin is not used with thermistor
    What settings should I make?

    1. I do not see any pull-up on the CE pin. You need to drive the CE pin HIGH to enable charging.
    →Circuit diagram corrected, short the J6 jumper and drive it HIGH.
    Looking at the specifications, it seems to have a 1MΩ pull-down resistor built in, so
    Is it correct to remove R49 and short the J6 jumper?

    2. Do you intend to use the thermistor with the battery back in? If so, make sure it is programmed correctly for the desired temperature range. If not, bias the TS pin to the correct voltage. For more information, see Section 8.3.18 of the datasheet. 3.
    →No thermistor is used.
    For applications that do not use the TS function, how should the TS pin be handled? 3.

    3. check the input current limit of 960mA.
    →As recognized.

    4. We calculated the charge current as 410mA instead of 40mA. The calculation is 3.3 * 120 / (100 + 120) / 20/.22.
    →I wanted the charging current to be 40mA.
    I changed R48 to 240kΩ.
    Also, I changed RSR back to the default value of 0.01Ω.

    5. Calculated the termination current as 13.6mA. Note that with a termination current of 13.6mA and a sense resistor of 0.22 ohms, the sense voltage is about 3mV. The accuracy of the termination at this voltage is between + / - 45% and + / - 25%.
    Since →ITERM≤ICHARGE/10.
    I changed R40 to 120Ω.
    Also, RSR was changed back to the default value of 0.01Ω.

    6. Battery regulated voltage is 1.8 * (1 + 360/100) or 8.28V.
    →As recognized.

    7. Check the charge timer for 2.33 hours.
    →I wanted to set the timer to 6 hours.
    I changed TTC C30 to 0.33uF.

    8. TP1 in the upper right corner is labeled VBAT. This is a system node. Are you planning to put a load on the system?
    →Sorry, I missed the correction.
    It has been corrected to a system node.

    Please check the above.

  • 0 in reply to user4863518
    TI__Mastermind 24075 points

    Hi,

    TS pin should be biased within the temp range specified in the EC table. They are specified as a % of the TS pull up rail, so biasing a voltage either using an external voltage source or resistor divider on TS such that TS voltage is fixed in the normal charging range will work.

  • 0 in reply to Kedar Manishankar
    Prodigy 140 points

    Thank you for confirming.

    I'm sorry, but I have one more question.
    When charging a battery with 7 cells
    Is it possible to define the number of cells to be charged?

  • 0 in reply to user4863518
    TI__Mastermind 24075 points

    Hi,

       The resistor divider at the VFB pin determines the total charge regulation voltage for the charger IC to charge. If your question is whether you can configure to only charge a certain number of cells out of your battery configuration, then this is not possible. The resistor divider can be configured to charge different number of total cells.