BQ25121: paired with the BQ51003, hardware only charging current only 2.00ma

Anthony Dobaj

Prodigy 230 points

Part Number: BQ25121
Other Parts Discussed in Thread: BQ51003

Why is the charging current into the battery only 2 mA before programming the BQ25121? schematic below

over 7 years ago

0 Anthony Dobaj over 7 years ago

Prodigy 230 points

In case it's difficult to read -

BQ51003: RILIM = 536, RFOD = 196

BQ25121: RILIM = 499, RISET = 49.9, RITERM = 49.9

0 Raheem over 7 years ago in reply to Anthony Dobaj

TI__Mastermind 21590 points

Hello Anthony,
If the battery voltage is below 3V, the IC will charge the battery with the pre-charge current until the battery voltage gets to 3V which is when the fast charge begins. The recharge current is set to 2mA by default before programming through I2C.
Regards,
Raheem

0 Anthony Dobaj over 7 years ago in reply to Raheem

Prodigy 230 points

OK, that certainly explains that, thanks. Which, if any, of the registers are non-volatile?

0 Raheem over 7 years ago in reply to Anthony Dobaj

TI__Mastermind 21590 points

Anthony,
The registers go back to the defaults setting stated in the datasheet when power is removed and reinserted. Also i'll suggest you revisit your calculations for RISET and RITERM. The minimum for RISET is 665 ohms.

Regards,
Raheem

0 Anthony Dobaj over 7 years ago in reply to Raheem

Prodigy 230 points

sorry, I misstated the resistor values above for ISET and ITERM, both are 49.9K ohms, my apologies.

Power management

Power management forum

BQ25121: paired with the BQ51003, hardware only charging current only 2.00ma