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TPS2231's recommended pin assignments on customer's board.

Tsuguhiko Asai
Expert 1260 points
Other Parts Discussed in Thread: TPS2231

Please teach us pin placement of TPS2231.
Even if a customer makes these pins an open on their board,
is not there the problem?

SYSRST#
STBY#
SHDN#

Datasheet says "Internally pulled up to AUXIN".
Therefore we expect that these pins do not have any problem by an open status.

Best Regards
Tsuguhiko Asai

  • 0
    TI__Expert 7990 points

    You will need to assess your application and circuit board.

    Per the datasheet, the pullup is a resistor that provides a minimum of 10uA with Vaux @ 3.3V, or 330K equivalent.  To achieve a 2V input (assuming that there is board leakage to ground), the board needs to leak less than (3.3V-2V)/330k = 4uA, or an equivalnet leakage of 2V/4uA = 500k.

    If you believe your leakage is greater, then tie the pins up to Vaux or use an external pullup.  If your leakage is less, the pins may be left open.

  • 0 in reply to Martin Patoka
    Expert 1260 points

    Dear Martin-San

    Thank you very much for a kind answer.

    Please teach it by addition.

    Our customer is going to perform the On/Off change of the following output signal

    only in CPPE# of ExpressCard, without using these pins. Is there the problem?

    ・ 3.3VOUT

     ・ AUXOUT

     ・ 1.5VOUT

  • 0 in reply to Tsuguhiko Asai
    TI__Expert 7990 points

    I am sorry, I don't understand the question.  Could you provide more detail?

  • 0 in reply to Martin Patoka
    Expert 1260 points

    Dear Martin-San,

    I am sorry that my explanation is short

    Please refer to a figure in Description of the data sheet (P1)

    The customer is curious whether the following usage is possible about this IC.

    ・CPPE ← Express Card (Use)

    ・SHDN → Host Chip Set/Lock Circuits (Not Use)

    ・STBY → Host Chip Set/Lock Circuits (Not Use)

    ・SYSRST → Host Chip Set/Lock Circuits (Not Use)

    I think that this IC and ExpressCard can communicate even the method mentioned above.

  • 0 in reply to Tsuguhiko Asai
    TI__Expert 7990 points

    Operation of these functions is described in the tables on page 12, "Power States" on p13, and "Application Information" on starting on p19. 

    The switch device will operate and deliver power,  however these various functions will not be supported.  For example, a card will not be put into a standby mode, nor will a system-controlled shutdown, etc.  The customer must determine if this is acceptable operation.