BQ24780S: The condition of entering hybrid boost mode

Hardy Xue

Part Number: BQ24780S

Hi Team,

My customer found a issue that they cannot enter hybrid boost mode when battery fully charged. Please see the log as attachment.

I checked that system already meet all required condition of hybrid boost mode as below:

1. 0x37[2] = 1

2. Input current exceed 0x3F*107% and 0x3F higher than 1536mA.

3. High input current keep numerous ms that is more than 0x37[4:3] setting.

4. WATCHDOG Timer doesn’t time out.

5. Battery voltage doesn’t lower than 0x3b[15:14] setting.

But I tried to re-write 0x0000 to 15h(Charge Voltage), the system can enter hybrid boost successfully. I would like to know why ChargeVoltage will affect system enter hybrid boost mode?

zgp.txt

Best regards,

Hardy

over 1 year ago

0 Pengzhao Zhu over 1 year ago

TI__Genius 11385 points

Hi Hardy,

It is probably the charge voltage register got changed for some reason.

My suspicion is that BAT_DEPL_VTH (0x3b[15:14]) references the charge voltage register. If the charge voltage register is off by some amount, it could affect hybrid boost operation.

However, I am glad to hear it is fixed now.

Thanks,

Peng

0 Hardy Xue over 1 year ago in reply to Pengzhao Zhu

TI__Expert 3600 points

Hi Peng,

My customer use our charger for long time on many projects. They always set 15h to 0x0000 when battery fully charged. But our datasheet doesn't mention about 15h setting is one of conditions to enter hybrid boost mode. They need TI's comment to discuss with end customer also.

So, could you please provide a official comment so that I can communicate with customer?

Or,

do we need to update datasheet?

Best regards,

Hardy

0 Pengzhao Zhu over 1 year ago in reply to Hardy Xue

TI__Genius 11385 points

Hi Hardy,

I tested on the EVM.

20VIN. 8.4V Charge Voltage setting (REG15). The SRN side of the sense resistor is measured at 8.513V. Input current setting is 1792mA (1536mA works too). 2A load on VSYS. FDPM_VTH is set to 107%.

The part is able to go into hybrid boost mode. I don't see any evidence of the part can't go into hybrid boost mode when battery is fully charged.

Thanks,

Peng

0 Hardy Xue over 1 year ago in reply to Pengzhao Zhu

TI__Expert 3600 points

Hi Peng,

Could you please try below step?

1. Battery is fully charged and connected to EVM.

2. Set ChargeCurrent 14h and ChargeVoltage 15h to 0x00.

3. Run heavy load to let input current >107% of 3Fh.

Best regards,

Hardy

0 Pengzhao Zhu over 1 year ago in reply to Hardy Xue

TI__Genius 11385 points

Hi Hardy,

I typically only bench test to rule out any possibility of IC issue (which I have proved it is not an IC issue). I have shown the customer what they need to do to get hybrid boost working.

I don't usually do this follow-up question, but since I am going into the lab later for other jobs, I will check it for you as well.

I will get back to you.

Thanks,

Peng