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LP5907: Dropout or RDS,on over temperature

Antenna_Head
Genius 12175 points
Part Number: LP5907
Other Parts Discussed in Thread: TPS7A20

Tool/software:

A customer is working on a design verification exercise and needs to know how either the dropout voltage or the RDS,on of the pass element changes over temperature.

The load current is only 15 mA even at hot temperature (125C) so we expect the drop out voltage to be quite low.

nevertheless, we need to show some analysis that it's been considered.

Can you provide some information on how much the drop out voltage or RDS,on will change (percentage or ratio is fine) at temperature vs. typical?

thanks!

-Steve

  • 0
    TI__Mastermind 36565 points

    Hi Steve,

    Please give me a couple of days to review this and see if we have any direct data already collected. This part is older now (the modern device is the TPS7A20) so it takes a little longer to sift through the archives.  If we don't have anything specific then I can give you some assistance with reviewing the information in the datasheet to help guide the customer.  Can you remind me who the customer is?

    Thanks,

    Stephen

  • 0 in reply to Stephen Ziel
    TI__Genius 12175 points

    Any update on this?  Thanks!

  • 0 in reply to Antenna_Head
    TI__Mastermind 36565 points

    Hi Steve,

    I've looked and I cannot locate data already captured for this specific condition. The data in the datasheet is not across temperature.  We can capture a measurement on an EVM but we won't have that measurement until the end of next week due to resources and procuring hardware.  Let me know if taking a measurement across temperature on an EVM will work for this customer.

    Thanks,

    Stephen

  • 0 in reply to Stephen Ziel
    TI__Genius 12175 points

    Can we get a estimate of how much it will change?  This can be a very conservative estimate given how little the load current actually is.  They are simply doing a corners analysis and just need to make sure they have some headroom over temperature.  A temperature coefficient for RDS,ON for just about LDO made on the same process is probably close enough.

    I think we can get a little creative here, and hoping to not put you through any additional work if we can look something/anything up that could apply.

  • 0 in reply to Antenna_Head
    TI__Mastermind 36565 points

    Hi Steve,

    I've reached out to design and I'll let you know when I hear back.

    Thanks,

    Stephen

  • 0 in reply to Stephen Ziel
    TI__Mastermind 36565 points

    Hi Steve,

    Design says the estimated change will be -16% from 25C to -40C, and the estimated change will be +25% increase going from 25C to 125C.  Let me know if you need anything else.

    Thanks,

    Stephen