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TPS25751: EEPROM gets detected when powered from battery but not when powered from VBUS

Pratham M
Prodigy 80 points
Part Number: TPS25751
Other Parts Discussed in Thread: BQ25798,

Tool/software:

Hi there, 

We are using the TPS25751 and BQ25798 for out PD charging and PD powered system design along with an MPU running linux. 

Setup:

The ADCINx configuration of PD is set to AlwaysEnableSink and the BQ25798 is connected with I2Cc of TPS25751. 

Issues:

1. When Battery Connected: The TPS loads the configuration from EEPROM and goes to APP mode.

BOOT STATUS Reg reads: 0xa2f00018

 

2. When Powered from VBUS: The TPS doesn't even detect the EEPROM and tries to load the configuration from I2Ct.

BOOT STATUS Reg reads: 0x2620334

now when the system boots from battery (case-1) and when we connect the VBUS the system reboots after negotitaion and follows the case-2 again. 

What could be causing this?

Best Regards,

Pratham

  • +1
    TI__Guru 66681 points

    Hello,

    I am not certain as to why the following occurs:

    Pratham M said:
    now when the system boots from battery (case-1) and when we connect the VBUS the system reboots after negotitaion and follows the case-2 again. 

    The reason for the difference in behavior from item 1 to item 2 might be related to how the EEPROM and associated pullups are supplied.  Typically TI recommends using LDO_3V3.  LDO_3V3 will be source either from VIN_3V3 or VBUS (in the case of dead battery, no VIN_3V3 present).  If the EEPROM is powered from VIN_3V3 then it is possible that the system will only work when VIN_3V3 is supplied and will not work in the dead battery condition (powered from VBUS alone).

    Regards,

    Chris

  • 0 in reply to Chris Sterzik
    Prodigy 80 points

    Hi  

    Yes, that was the issue.

    Thank you.