BQ24296: Input Current Limit Value Changing

Thuan Vu

Part Number: BQ24296

I am observing that the Input current limit value (REG00[2:0]) is changing at run time to the default value(111). Our SW is customizing the register values and besides this value, everything else is what is being programmed. Is there a possibility that the BQ24296 is changing this value?

over 8 years ago

0 Joel Hernandez II over 8 years ago

TI__Mastermind 25800 points

Hey Thuan,

What are your runtime conditions (i.e. load current, battery voltage and size, initial register settings or register setting control scheme, input voltage at the pin level, power capability of your input source)?

Regards,
Joel H

0 Thuan Vu over 8 years ago in reply to Joel Hernandez II

Intellectual 460 points

Hi Joel,

Load current: 400 mA nominal, 3 A peak

Battery Voltage: 4.2 V, 980 mAH but charging to 4 V

Initial register settings:

reg[0x0] = 0x24
reg[0x1] = 0x1f
reg[0x2] = 0x79
reg[0x3] = 0x10
reg[0x4] = 0x7e
reg[0x5] = 0xba
reg[0x6] = 0x73
reg[0x7] = 0x4b

Control scheme: SW is changing fast rate charging value REG02 between 0x79 and 0x1d depending on battery temperature

Input voltage at VBUS pins: 4.6 V

Capability of input source: 5 V, 2A

Regards,

Thuan

0 Joel Hernandez II over 8 years ago in reply to Thuan Vu

TI__Mastermind 25800 points

Hey Thuan,

Are the register changing when you plug in an adapter/USB source to VBUS? Or do they change even when you are in the Battery-only operation?

Is this the TI EVM or is this a custom board?

Lastly, what do you have the PSEL pulled to - High or Low?

Regards,

Joel H

0 Thuan Vu over 8 years ago in reply to Joel Hernandez II

Intellectual 460 points

It seems like the register is changing when I plug in the adapter.

It is a custom board.

PSEL is pulled low.

Thanks,
Thuan

0 Joel Hernandez II over 8 years ago in reply to Thuan Vu

TI__Mastermind 25800 points

Hey Thuan,

So the charger will always re-run input current limit detection when the input source is applied.

With PSEL being low, it will reset the IINDPM limit to 3A input current limit (max) every time the input is applied.

One solution: every time an adapter is plugged in, change the IINDPM setting back to your desired value.

Second solution: If you are looking for a fixed IINDPM value (which it seems like you are at 1A, set your ILIM pin resistor value such that ILIM = 1A. The formula is ILIM = K_ILIM/R_ILIM.

Regards,
Joel H

0 Thuan Vu over 8 years ago in reply to Joel Hernandez II

Intellectual 460 points

Thanks! I think that's the issue.

Regards,
Thuan

0 Joel Hernandez II over 8 years ago in reply to Thuan Vu

TI__Mastermind 25800 points

No problem Thuan! Let us know if you have any other questions.

If that answered your question, please hit Verify Answer on the previous post.

Thanks,
Joel H

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BQ24296: Input Current Limit Value Changing