TPS25750: Dead Battery Mode

Jonathan Navor

Part Number: TPS25750

Hi Team,

Good day! We're having issues with the dead battery mode.

We want the chip to wait until we clear the dead battery flag (but it basically exits dead battery mode immediately and reads it's configuration).

Before our host controller is up and can clear the dead battery flag. How do we get the chip to wait until a host controller clears the dead battery flag?

Best regards,

Jonathan

over 2 years ago

+1 Raymond Lin over 2 years ago

TI__Mastermind 34736 points

Hi Jonathon,

By default, the TPS25750 will wait for a host controller to send I2C commands to clear the dead-battery flag using 4cc command 'DBfg' - Clear Dead Battery Flag (page 59 of the Host Interface Technical Reference Manual):

In a dead-battery state, the PD controller will receive power through VBUS input until the dead-battery flag is cleared. The dead-battery flag can also be cleared through a hard reset on the PD controller which will clear all flags and current status the PD was in (page 32 of Datasheet):

The TPS25750 can still function from a dead-battery state through VBUS:

Can you read into register 0x26 (POWER_PATH_STATUS register) and see what Bytes 15:14 (PowerSource) is currently at? If it's 10b, then the PD is still in dead-battery state, otherwise something else is causing the PD to exit this state.

Thanks and Regards,

Raymond Lin

0 Christopher Lim1 over 2 years ago in reply to Raymond Lin

TI__Mastermind 37855 points

Hi Jonathan,

We re-opened this thread.

Can you describe more of what's happening in your system. I am interested in knowing how you get into dead battery mode, and what the system looks like when it automatically clears.

Also, can you let me know what you see on the register that Raymond asked about?

Raymond Lin said:
Can you read into register 0x26 (POWER_PATH_STATUS register) and see what Bytes 15:14 (PowerSource) is currently at? If it's 10b, then the PD is still in dead-battery state, otherwise something else is causing the PD to exit this state.

Thanks and Regards,

Chris

0 Victor Franco over 2 years ago in reply to Christopher Lim1

Prodigy 75 points

Hello Chris,

Reading 0x26 give me the reading below

0x05 0x00 0x30 0x00 0x00

Thanks,

Victor

0 Raymond Lin over 2 years ago in reply to Victor Franco

TI__Mastermind 34736 points

Hi Victor,

I'll take a look into this and provide a response by Wednesday next week.

Thanks and Regards,

Raymond Lin

0 Chris Read over 2 years ago in reply to Raymond Lin

Genius 3345 points

Hi Raymond, any update?

0 Raymond Lin over 2 years ago in reply to Chris Read

TI__Mastermind 34736 points

Hi Chris,

Based on the register 0x26 read, it doesn't seem like the dead battery flag is set. Was this register read done before or after sending 'DBfg' command?

Thanks and Regards,
Raymond Lin

0 Chris Read over 2 years ago in reply to Raymond Lin

Genius 3345 points

We never sent the 'DBfg' command.

0 Raymond Lin over 2 years ago in reply to Chris Read

TI__Mastermind 34736 points

Hi Chris,

is it possible for you to check to see if there is 3.3V present at VIN_3V3?

Thanks and Regards,

Raymond Lin

0 Christopher Lim1 over 2 years ago in reply to Victor Franco

TI__Mastermind 37855 points

Hi Victor,

What device are you using to read the register?

If you are using Aardvark, you may need to read 6 Bytes. The first byte that the Aardvark returns might just be the data size.

Here I wanted 8 bytes of data and had the Aardvark read 9.

Thanks and Regards,

Chris

0 Christopher Lim1 over 2 years ago in reply to Christopher Lim1

TI__Mastermind 37855 points

Hi,

This image may be a bit more clear. This is a setup using Aardvark + 25750. The length column corresponds to the number of Data bytes. The Byte that Raymond and I want to see is the right most byte(which corresponds to byte 5 of register 0x26).

Thanks and Regards,

Chris

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TPS25750: Dead Battery Mode