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TPS24720 Current Limit Monitor Sensitivity

Samuel Jaffe
Mastermind 25590 points
Other Parts Discussed in Thread: TPS24720

Hi E2E,

I have a customer who's using the TPS24720.  The customer wants to use the IMON pin to monitor the current, but requires readings down to 1mA with a 250mA current limit.  Using the maximum acceptable value for Rsense (~180mOhm), can we change Rimon, Rset, or something else to increase this sensitivity at low currents?

Thanks!

-Sam

  • 0
    TI__Expert 5940 points

    Sam,

    The TPS24720 will not reliably provide current sensing down to 1mA * 180mohm Rsns = 180uV across Rsns.   In the ES table, under "SET", the Vos of the 'Set' to 'Sense' inputs to the current amp can be +/- 1.5mv so 180uV cannot be reliably read by the current amp to produce meaningful data.  This is true of any Hotswap IC, manufacturer independent.  For that fine tuned resolution at low currents, look at the INA current sense amps.  The recommended operation range for good CL and Fast trip operation + current sensing readings is between 10mv and 42mv on Rsns. 

    Brian

  • 0 in reply to Brian Daugherty
    TI__Mastermind 25590 points

    Brian,

    Thanks for the feedback.  Sadly I think this functionality is not worth the price in this particular case.  In the interest of cost, we're looking at eFuses instead on this thread.  What do you think?

  • 0 in reply to Samuel Jaffe
    TI__Expert 5940 points
    250mA is more efuse territory than TPS24720, not to say you cannot use a discrete solution. Cost/space as you note. I suspect the efuse selection will have limitations at the lower end of its current range, as the TPS24720 and other HSC's do. Will let the efuse team comment further in the other thread. If you need any further assistence, let me know.

    Brian