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TPS62840: tps62840 SW output state when EN or RUN/STOP signals are ON

Eric Dj
Expert 4130 points
Part Number: TPS62840

Team, I would like to know the state (high impedance, high, low) of the SW pins when either the EN or RUN/STOP signals are activated. The idea is to use one of those pins to disconnect the tps62840 from the rest of the circuitry in the production bench. I would assume that both the P and N FETs are off (when EN is active) and thereby leaving that pin with an high impedance state.

Thanks, Eric 

  • 0
    TI__Expert 7585 points

    Hi Eric,

    Thank you for your question.

    I did some lab measurements, and those are the results:

    1. If EN is low, the SW pin has a low impedance (in the order of 30 Ω) to ground. This is related to the output discharge function. Referring to the datasheet:
    2. Instead, during STOP mode, the device output is clamped at a value equal to: Vout - 0.5V.  Again, referring to the datasheet:

    In order to achieve this clamping, the high side Mosfet is not OFF (it draws a small current to keep the output from discharging completely).

    To sum up, neither of these configurations set the SW node to an high impedance state.

    Please ask if you have any more questions.

    Thank you,

    Stefano

    All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml).