BQ25703A: BQ25703A Regarding charging

user3955621

Part Number: BQ25703A

Hi TI team.

I use BQ25703A, but when I stop charging, 24pin (HIDRV2) and 31pin (HIDRV1) become 500mV and the connected FET turns on.

By turning on the FET, 700uA will be consumed and the battery capacity will be reduced.

Nch FET uses RTR025N05FRATL.

Please tell me how to solve it.

over 5 years ago

0 user3955621 over 5 years ago

Prodigy 110 points

I have additional questions

Please tell me the quiescent current of VSYS.

We believe that battery capacity is decreasing due to quiescent current.

0 Shishuo Zhao over 5 years ago in reply to user3955621

TI__Expert 3320 points

Hi there,

I assume you are battery only mode but doesn't enable low power mode operation highlighted below. If you configure REG 12h[15]=1 to enable low power mode and configure REG 30H[13]=0 to disable independent comparator circuit, the quiescent current shoudl reduce to 22uA range.

Regards

Shishuo

0 user3955621 over 5 years ago in reply to Shishuo Zhao

Prodigy 110 points

Hi,Ti team

I set it to 22uA.

Is it possible to lower it further with other registers?

0 user3955621 over 5 years ago in reply to user3955621

Prodigy 110 points

I have additional questions.

Vsys is now 22uA, but when you look at the QUIESCENT CURRENT in the data sheet, all the currents listed below are listed as 22uA.

ISRN + ISRP + ISW2 + IBTST2 + ISW1 + IBTST1 + ACP + IACN + IVBUS + IVSYS

We think that the current value will decrease further.

0 Shishuo Zhao over 5 years ago in reply to user3955621

TI__Expert 3320 points

Hi There:

Do you have only battery connected? If only battery is connected,under low power mode you should only see 22uA consuming current out of battery.

The 500mV voltage you mentioned above should already be gone. For the VSYS 22uA, do you mean there is 22uA load on the VSYS? I am trying to understand the situation here.

Regards

Shishuo

0 user3955621 over 5 years ago in reply to Shishuo Zhao

Prodigy 110 points

Hi TI Team.

The battery is connected.

It became 22uA.

Thank you.

0 user3955621 over 5 years ago in reply to user3955621

Prodigy 110 points

Hi Ti team.

I have additional questions.

Does BQ25703A have a function to automatically stop charging when it is fully charged?

0 user3955621 over 5 years ago in reply to user3955621

Prodigy 110 points

Hi Ti team.

What is the minimum battery voltage that can be charged?

BATTERY UNDER VOLTAGE LOCKOUT COMPARATOR was described as 2.2 to 2.6V.

0 Shishuo Zhao over 5 years ago in reply to user3955621

TI__Expert 3320 points

Hi There,

BQ25703A doesn't stop autonomous charging, so it can't stop charge automatically has to be terminated by host.

The charge voltage range from 1.024V to 19.2V. The battery under voltage lock is defined for battery only mode to start up the charger.

Regards

0 user3955621 over 5 years ago in reply to Shishuo Zhao

Prodigy 110 points

Hi TI team

Is it necessary to set the register to charge at 1.024 ~ 19.2V?

Please tell me the meaning of SYSTEM VOLTAGE REGULATION and VOLTAGE LOCKOUT COMPARATOR.

thank you

0 Shishuo Zhao over 5 years ago in reply to user3955621

TI__Expert 3320 points

Hi There,

There is a default charge voltage based on your cell setting:

1S: 4.2V; 2S:8.4V, 3S:12.6V, 4S: 16.8V

For SYSTEM VOLTAGE REGULATION:

When VBAT>VSYS_MIN: SYSTEM VOLTAGE REGULATION follows maximum system voltage regulation shown below when charge is disabled.

VSYS=VBAT+160mV

When VBAT<VSYS_MIN: SYSTEM VOLTAGE REGULATION follows minimum system voltage regulation shown below.

VSYS=VSYS_MIN

For VOLTAGE LOCKOUT COMPARATOR, There are two:

1, VBUS under voltage lockout comparator for forward mode: Threshold to determine if VBUS is high enough to enable charger converter. If is lower than this threshold, converter will be shutdown.

2, Battery under voltage lockout for OTG mode:Threshold to determine if VBAT is high enough to enable charger converter. If is lower than this threshold, converter will be shutdown.

Regards

Power management

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BQ25703A: BQ25703A Regarding charging