BQ25713: Registers fail to initialize

Part Number: BQ25713

Hi Team,

We have a BQ25713 that powers up when its battery is installed. There is no input voltage (Vbus) yet. The device powers up and supplies power to the downstream device as expected, but some of the I2C registers don’t seem to behave as expected in this state. 0x0C/0x0D and 0x04/0x05 don’t initialize to the expected POR values. Also, when I try and write to addresses 0x0A & 0x0B, the I2C write transaction succeeds but the write doesn’t take effect – reading back the register immediately gives 0x00 every time. There might be others – I haven’t done a comprehensive search.

It seems to work fine once the input power (Vbus) is present, so I suspect that certain parts of the chip are not intended to be used when running off of the battery only. I just want to confirm this to make sure I’m not ignoring a more serious problem. If so, can I get a list of all of the affected registers? If not, I’ll have to provide more details to figure out what’s actually going on.

Regards,

over 3 years ago

0 Tiger Zhou over 3 years ago

TI__Mastermind 32745 points

Hi, RJ,

This is normal. The registers you mentioned are set up during startup, from the input power. source. see datasheet 9.3.3 Power-Up From DC Source.

0 Jason Mills over 3 years ago in reply to Tiger Zhou

Prodigy 10 points

Hi Tiger,

Thanks for the confirmation. I'm the customer that originally raised the question.

Are there any other registers that aren't fully functional when the DC source is absent, or did I find them all?

Regards,

Jason.

0 Tiger Zhou over 3 years ago in reply to Jason Mills

TI__Mastermind 32745 points

All the registers are fully functional. You only need to set a few registers to start the operation, such as charge voltage and charge current. You can leave the rest of registers default value, unchanged.

Power management

Power management forum

BQ25713: Registers fail to initialize