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TPS25750: Incorrect register description in : TPS25750 Host Interface Technical Reference Manual

Olav Birkeland
Prodigy 20 points

Part Number: TPS25750
Other Parts Discussed in Thread: TPS25751

In the "TPS25750 Host Interface Technical Reference Manual" on page 23,

bits 14:12 value 2h is described as "Reserved". The correct is probably similar to bits 8:9 value 2h (changed to PP3) "PP3 switch enabled (system output)"

  • 0
    TI__Genius 13880 points

    After review, the register description in the TRM is correct.

    Kind regards,

    Conner Gillette

  • 0 in reply to Conner Gillette
    Prodigy 20 points

    Then please explain this.

    PP3 is a bidirectional switch, current can be both sourced and sink via this port, but there are no setting for "switch on as output". In other words, based on the Reference manual this port can NOT source power!

    However, in my setup, when PP3 is definitely sourcing power, register bits 14:12 is set to 2h, and this makes perfect sense, except for the description being "Reserved" 

    Look at the description in the reference manual, based on this the PP3 switch can be either:

    - OFF (Disabled)

    - OFF (disabled) due to fault

    - ON (Enabled) as an input

    But it cant be on as an output! (and this is obviously wrong)

  • +1 in reply to Olav Birkeland
    TI__Genius 13880 points

    The bit being Reserved does not preclude the switch from behaving as an output, it only means to ignore the bit.

    However, yes, that bit does denote "PP3 switch enabled (system output)". Why it was chosen to be Reserved upon definition of the part, I do not know. Its successor part, the TPS25751, does have bit 2h of PP3Switch shown as "PP3 switch enabled (system output)".

    Kind regards,

    Conner Gillette

  • 0 in reply to Conner Gillette
    Prodigy 20 points

    Thanks. In my opinion the reference manual is incorrect. A setting being marked as reserved is not intended to be used, it might be in future parts (as you told it is), but in this case it is obviously also being used for TPS25750, as it has to be since the port by design is supposed to have that functionality.

    Best regards

    Olav

  • 0 in reply to Olav Birkeland
    TI__Genius 13880 points

    Thank you for the feedback Olav. I will bring this up to the Systems Team.

    Kind regards,

    Conner Gillette