BQ24800: Battery Only Boost Mode exit when ACDET < 0.6V

William Courbat

Part Number: BQ24800

Tool/software:

Hello,

We made a prototype of our new electronic and the BQ24800 keeps exiting Battery Only Boost Mode when ACDET < 0.6V. Could you help me understand why this is happening? Here are info and things I've tried:

Here are my registers:

("Charge Option 0 ", 0x12, 0x0018),

("Charge Option 1 ", 0x3B, 0x0E90),

("Charge Option 2 ", 0x38, 0x00C0),

("Charge Option 3 ", 0x37, 0x94C0),

("Prochot option 0 ", 0x3C, 0x0000),

("Prochot Option 1 ", 0x3D, 0x0000),

("Charge Current ", 0x14, 1472), // mA

("Charge Voltage ", 0x15, 6992), // mV

("Discharge Current ", 0x39, 3072), // mA

("Input Current ", 0x3F, 2304), // mA

("Minimum System Voltage", 0x3E, 8500), // mV

- 0x38 goes from 00C0 to 0080 when ACDET becomes lower than 0.6V (EN_BATT_BOOST is disabled). If I reset the register to 00C0 it works just fine.

- REGN stays at 6V during the event

- VBAT is not dropping

In blue is the voltage at the output of the adapter, dropping. In purple, is the system voltage. Battery Boost kicks in and goes from 12V to 10V, when adapter voltage goes below 2.4V (ACDET = 0.23* Adapter Voltage in my case so it corresponds to ACDET = 0.6V)), the system exit Battery Boost and I observe just the battery voltage on system voltage.

The threshold of ACDET = 2.4V is when adapter voltage is 10.3V

I've turned things upside down and in all directions and I still can't figure out why this is happening. Do you have any clues of what could be the reason?

Thanks a lot!

William

6 months ago

0 Christian Moyer 6 months ago

TI__Mastermind 32236 points

Hello William,

Do you have hybrid boost mode enbaled?

Do you see this same behavior when hybrid boost mode is disabled?

My concerned is when you first see this boost behavior, it's actually hybrid boost mode.

Best Regards,

Christian

0 William Courbat 6 months ago in reply to Christian Moyer

Prodigy 20 points

Hello Christian,

Thank you for your answer. I checked the hybrid boost mode is disabled and stays disabled no matter what I do.

However, I noticed that increasing the discharge current from 3000mA to 4000mA solves the issue. It's strange as my battery current during discharge is around 200-300mA. Could it be that when the BQ24800 detects ACDET < 0.6V, there is a peak current drawn by the system? I tried to check with an oscilloscope current probe, but noise was high and I didn't see a burst of current when ACDET = 0.6V.

If I may add another question: I see that when ACDET < 2.4V, it triggers an event that resets the Charging Current to its POR value which is 0 (page 45 of the datasheet). Is there a way to prevent that? If we have several back and forth of adapter plugin we need to reset the Charging Current in between each time which is not always possible.

Best,

William

+1 Christian Moyer 6 months ago in reply to William Courbat

TI__Mastermind 32236 points

Hello William,

William Courbat said:
However, I noticed that increasing the discharge current from 3000mA to 4000mA solves the issue. It's strange as my battery current during discharge is around 200-300mA. Could it be that when the BQ24800 detects ACDET < 0.6V, there is a peak current drawn by the system? I tried to check with an oscilloscope current probe, but noise was high and I didn't see a burst of current when ACDET = 0.6V.

This is possible.

William Courbat said:
If I may add another question: I see that when ACDET < 2.4V, it triggers an event that resets the Charging Current to its POR value which is 0 (page 45 of the datasheet). Is there a way to prevent that? If we have several back and forth of adapter plugin we need to reset the Charging Current in between each time which is not always possible.

Unfortunately, we do not have a way to disable this feature.

Best Regards,

Christian.

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BQ24800: Battery Only Boost Mode exit when ACDET < 0.6V