BQ25122: Set Fast Charge Current?

Christopher Chorey

Part Number: BQ25122
Other Parts Discussed in Thread: EV2400,

I'm working with the BQ25122EVM & have latest BQ Studio installed and EV2400.

My question is about how to set the fast charge current, if I read the data sheet correctly, writing to the Fast Charge Control Register (0x05) should override the external resistor at ISET, correct? I am trying to set the fast charge current to 300mA, but I can see that I am only getting 40 - 50 mA. The status register indicates that the chip is charging. Current values for all of the registers is below:

0x00 = 41

0x01 = 00

0x02 = 88

0x03 = FC

0x04 = 82

0x05 = 78

0x06 = 82

0x07 = FC

0x08 = 60

0x09 = 3A

0x0A = 00

0x0B = 42

over 6 years ago

0 Christopher Chorey over 6 years ago

Prodigy 170 points

Update: By Playing around I found that if I set Register 0x03 to xF8 (instead of xFC) the charge current goes up to 300mA. Issue resolved.

0 Gautham over 6 years ago

TI__Genius 12485 points

Christopher,

You also need to set ILIM which you are doing. However, i would ask that you also set the box "Auto Read: OFF" to read every 10sec to keep the watchdog from resetting the registers.

Are you using a battery?

regards,

Gautham

0 Christopher Chorey over 6 years ago in reply to Gautham

Prodigy 170 points

Hi Gautham;

I found that if I set register x03 to xF8 instead of xFC , the charge current goes to ~300mA. Not sure if this is a bug? The notes for Reg 03 in the datasheet state that if the value is set above 300mA, then it will default to 300mA.

Regards;

Chris

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BQ25122: Set Fast Charge Current?