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TPS7H2201-SP: tps7h2201-sp: Internal Pull-down Resistor

Akash Malhotra
Prodigy 10 points
Part Number: TPS7H2201-SP

Hello.

I have a couple questions about a datasheet for a load switch. The part number is tps7h2201-sp

In figures 4 and 5, max pull down spec is at 138 ohms and graph doesn't go anywhere near that for load switch Rpd. How was this value determined?

If we consider BOL, EOL, Bond, TMP, SOLD tolerances, is it better to use max or typical value of the pull-down resistance? We are operating in a region of about 0 to 30 deg C, which correspond to about 18 to 23 ohms respectively.

  • 0
    TI__Mastermind 22065 points

    Hey Akash,

    We do statistical analysis on a population of parts to determine the maximum resistance value.
    This statistical analysis takes into account Life, Temp, Radiation, Burn-in, and part to part variation.
    All graphs show typical data which may or may not be close to what the statistical maximum is.

    As far as our suggestion for handling this in your own design, making sure you can handle up to the maximum resistance of the pull down is going to be important for robust designs.

    Thanks,
    Daniel

  • 0 in reply to Daniel Hartung
    TI__Mastermind 22065 points

    Hey Akash,

    I will quickly clarify that when I said we took into account Life, I meant Group C by MIL standard.

    Thanks,
    Daniel

  • 0 in reply to Daniel Hartung
    Prodigy 10 points

    Daniel, thank you very much for the responses. I have one more question as a follow-up. I noticed that in figures 4 and 5, the input voltage has a significant impact on the pull-down resistance value as well. Given such a large variation for Rpd with respect to input voltage, I wanted to ask what the relationship is between the two as the datasheet doesn't seem to make that clear. Is there an equation?

  • 0 in reply to Akash Malhotra
    TI__Mastermind 22065 points

    Hey Akash,

    There is no equation for pull-down resistance vs. input voltage
    The relationship is simply drifts in the specifications due to changes in the input voltage.

    Note that this drift is covered by the electrical specification.

    Thanks,
    Daniel

  • 0 in reply to Daniel Hartung
    Prodigy 10 points

    Would we expect the pull down resistance to go up to 138 ohms (max spec pull down resistance) given that we're operating on a 5V input? Is it possible we can guarantee a lower pull-down resistance than the 138 ohm?

  • 0 in reply to Akash Malhotra
    TI__Expert 7085 points

    Hi Akash,

    The max pull down resistance for both ILTIMER and RTIMER pull downs is 153 ohms, not 138 ohms. Just wanted to make sure you were aware of this.

    (Images can be enlarged by clicking them)

    I may be able to check if there is data for the 5V VIN case since the pull down resistances are typically lower at higher VIN, however, this would only be general information about what to expect. The only guarantee we can make is based on what the electrical characteristics in the datasheet say, which is that the maximum pull down resistance for both timers is 153 ohms. 

    Thanks,

    Sarah