BQ25121A: Problem with ship mode

Keith Creedy

Part Number: BQ25121A

Hello,

We would like the end-user of our device to engage ship mode to turn the device off.

When we follow the sequencing as in the datasheet, the device bricks and cannot wake up (not with MR or with VIN). Holding MR low to activate reset doesn't wake up or reset the device.

Our sequence: VIN HIGH, CD HIGH, MR HIGH, i2c write (0x20 to reg 0x00h), VIN LOW.

The result is:

VSYS = 0.6mV

LDO = ~105mV

PMID = VBAT

Current consumption = 0.44mA (for comparison, our device consumes 0.07mA when everything is in sleep mode)

over 4 years ago

0 Anthony P Pham over 4 years ago

TI__Mastermind 23410 points

Hi,

The device only enters ship mode when VIN is less than VUVLO followed by an I2C command or a long button press with MRREC set to 0. Be sure that since you will be in a battery only mode, you will need to put the device in the active battery mode by driving /CD high. This will put the device in active battery mode where you can send the I2C command to toggle the ship mode bit.

0 Keith Creedy over 4 years ago in reply to Anthony P Pham

Prodigy 20 points

Hi Anthony,

When I drop VIN to 0v then writing an I2C command, I get the same result as I described above.

When I drive CD HIGH, set MRREC to 0, then perform a long button press, the device resets and starts up in HI-Z mode.

0 Anthony P Pham over 4 years ago in reply to Keith Creedy

TI__Mastermind 23410 points

Hi,

Please try again with /MR pin high also and then the I2C command. Can you also try the other option for entering Ship mode (/CD high, VIN low, and /MR for longer than t_reset)?

0 Keith Creedy over 4 years ago in reply to Anthony P Pham

Prodigy 20 points

Hi Anthony,

I tried that and got the same result.

I don't think this is a problem with the sequencing. It appears that the sequencing is successful and the BQ tried to enter ship mode, but crashes and gets into a state as described in my first post.

0 Anthony P Pham over 4 years ago in reply to Keith Creedy

TI__Mastermind 23410 points

Hi,

Can you read the ship mode enable bit after you've enabled HIGH Z and put your self in active battery mode?

Power management

Power management forum

BQ25121A: Problem with ship mode