BQ24765: BQ24765 retaining the configured charge current

Prasad Achar

Part Number: BQ24765

We have custom designed the charger circuit for a RSS smart battery using BQ24765, The functionality on the custom board is working.

But when the board is powered ON, the default charging current is 256mA(approx), we reconfigure charge current to 1 Amps.

Once the DC jack(12VDC) is removed the configured parameters are not retained, the default configuration takes action i.e., 256mA.

The schematics are similar to the BQ24765EVM.

Note: The SMBus PU is to VREF (As per the EVM reference), which is not available after the DC jack is removed.

How do we retain the reconfigured values or how do i change the default value for my custom board.

Thanks

Prasad

over 1 year ago

0 Aya Khedr over 1 year ago

TI__Mastermind 23707 points

Hi Prasad,

Thank you for reaching out!

This behavior is normal. During power on, the device resets the register settings to default values.

Please see this FAQ for more information on how to change the value: https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1053477/faq-bq25710-will-bq25710-keep-the-old-register-settings-after-power-off

Best Regards,

Aya

0 Prasad Achar over 1 year ago

Prodigy 70 points

The VDDSMB is also connected to VREF, looks like this is the issue, still not tested.

As mentioned the VREF will be available only during the DC Jack input and not during the battery.

If somrthing else to be looked into please let me know.

0 Aya Khedr over 1 year ago in reply to Prasad Achar

TI__Mastermind 23707 points

Hi Prasad,

VREF can directly connect to VDDSMB as SMBus supply as stated in the datasheet (see below for reference).

An embedded controller (EC) or host controller (HC) is needed to write a new current value. Please let me know if you have additional questions.

Best Regards,

Aya

+1 Prasad Achar over 1 year ago in reply to Aya Khedr

Prodigy 70 points

Dear Aya,

Yes true, we have done the same as highlighted in yellow color,

From your last statement, you mean to say that the EC configured charging current value in my case 1024mAmps (when dc jack is inserted and charging) will be cleared to default current value(256ma) when the DC jack is removed and inserted again.

I am checking under what condition the EC configured charging current value will be retained till the battery is preset even though the DC jack is removed.

0 Prasad Achar over 1 year ago in reply to Prasad Achar

Prodigy 70 points

Sorry, got into some other issue.

The diode OR for VBAT and DCIN with resistor divider is provided to ACIN Pin in such a way that for VBAT, the voltage divider output is less than 2.4V at the ACOK comparator, This will make the VREF to be available during both VBAT and DCIN, by this the I2C is available during all time.

This change solved my issue..

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BQ24765: BQ24765 retaining the configured charge current