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Original question:

BQ25703A: BQ25703A register configurations

BQ25703AEVM-732：BQ25703AEVM-732：VIN Input 5V Charging Problem

user6063195
Prodigy 110 points
Part Number: BQ25703AEVM-732
Other Parts Discussed in Thread: EV2400, BQSTUDIO, BQ25703A

We use BQ25703AEVM-732 to debug. When the input power is set to 10V/3A, we can configure registers normally. When the input power is set to 5V/3A, we can only write and save "CHARGER OPTION 0". Other project configurations are unsuccessful and have been the default configuration. Do we need to change hardware or software?

  • 0
    TI__Mastermind 25800 points

    Hello,

    Is this using BQStudio and the EV2400 communication interface board, or are you using your on controller to communicate with the EVM?

    If through BQStudio, can you provide the register settings you are trying to program in either mode of operation? 

    Can you also confirm you testing setup? Jumper/shunt configurations, BAT voltage, SYS load? And how do you set the voltages?

    Be aware that if you start at 10V and lower the input voltage down to 5V without changing the InputVoltage Register, the converter will not operate or provide charge current. This register controls the VINDPM threshold of the charger, which by default is set to VIN - 1.28V. So starting with 10V, your default VINDPM threshold = 8.72V. If you lower the voltage to 5V from 10V, you will fall below this threshold and the charger will think the input source is extremely overloaded.

    Regards,

    Joel H

  • 0 in reply to Joel Hernandez II
    Prodigy 110 points

    Using EV2400 can solve my problem, and now I have a new problem. We use the I2C of the processor to configure the read and write registers. The configuration is unsuccessful. We can configure only OPTION 0, but the others are still not configurable.

  • 0 in reply to user6063195
    TI__Mastermind 25800 points

    Hello,

    So controlling the charger with the EV2400 is successful, correct?

    The EV2400 uses the standard I2C protocol to control the charger. I would suggest you analyze the I2C data packets you are sending to the BQ25703A, and compare them to the data packets sent by the EV2400 for reference. I would also suggest your review section 8.5 Programming of the datasheet to understand the format of reading and writing from/to the registers. This section is especially critical if you are attempting mutli-register reading and writing.

    Regards,
    Joel H