TPS65988: Port sourcing issues

Hi Yashodha,

Is your system booting in dead battery? Is the system taking power from VBUS?

If yes, the PD controller will be stuck in a dead battery state and will have limited sourcing capability. You will need to clear the dead battery flag for the Source port to advertise it's full capabilities.

If you have an I2C host, you can use the 'DBFG' command to clear the flag.

Thanks and Regards,

Chris

How do I know whether or not my system is booting dead battery?
What are the conditions that should be satisfied to exit dead battery mode?
Also, Can I check the status of the dead battery mode using GUI debug mode? if so, how to do that?

Looking for your further help!

Thank
Yashodha

Hi Yashodha,

Yashodha Salgado said:

How do I know whether or not my system is booting dead battery?

The PD controller can be powered two ways, you can (1) provide 3.3-V to VIN3V3 or you can (2) connect a USB-C source to the USB-C port.

If the PD controller boots in option 2, it boots in dead battery (no system/battery power). This will raise the dead battery flag.

Yashodha Salgado said:

What are the conditions that should be satisfied to exit dead battery mode?

There is an I2C command you can send called 'DBFG' to clear the flag. The command is referenced in the TRM found on the product page. You can send a DBFG in GUI debug mode. It will be found under the "Device X, Port X/Commands" section. 

Yashodha Salgado said:

Also, Can I check the status of the dead battery mode using GUI debug mode? if so, how to do that?

Yes, check the Power Path Status Register. Check the TRM for full information on the bitfields.

Thanks and Regards,

Chris

I'll check this

Thanks Chris.

Hi Yashodha,

Sounds good, let me know the results.

Where is the PB_VAR_DCDC voltage going? Is it attached to the power path in any way? You may end up seeing the advertisement for higher power source contracts working, but the actual voltage transitions fail if this is not connected properly. I also don't see where you are driving the PDO feedback dividers from, there does not appear to be net that connects it to the PD controller.

Thanks and Regards,

Chrsi

Hi Chirs,
This is how they connected.

Hi Yashodha,

Christopher Lim1 said:

Where is the PB_VAR_DCDC voltage going? Is it attached to the power path in any way? You may end up seeing the advertisement for higher power source contracts working, but the actual voltage transitions fail if this is not connected properly. I also don't see where you are driving the PDO feedback dividers from, there does not appear to be net that connects it to the PD controller.

Got it, thanks, I think you should be fine. Let me know how your testing goes.

Thanks and Regards,

Chris

Hi Christoper,

We checked the Dead battery flag and it is up. Is there any way to permanently disable this dead battery feature either software or hardware?

And what is the actual purpose of dead battery feature?

Thanks