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Original question:

TPS2H000-Q1: TPS2H000-Q1: Accuracy of current limit

TPS4H000-Q1: Current limit accuracy spec question

Alan O
Mastermind 32575 points
Part Number: TPS4H000-Q1

Hello, my customer would like to know the external current limit accuracy spec when I(limit) >= 50mA, but when Vvs is operating between 8V to 18V.  The datasheet spec is +/-25% (max/min) but this is specified at Vvs = 13.5V.  Does current limit accuracy get worse than this when Vvs is between 8V to 18V, and is there test data that shows the variation across Vvs range?

Also, if they use a CL resistor of 2.55kohm to set a nominal current limit of 94mA and the load current slowly increases, should they expect the current to overshoot by up 1.5x higher than the setpoint (or ~140mA)?

Thanks,
Alan

  • 0
    TI__Mastermind 34995 points

    Hello Alan,

    The current limit accuracy for 50mA can actually be applied to all temperatures/supply voltages in the device's operating range (5 V < VVS < 40 V; −40°C < TJ < 150°C). While the characterization test was done at 13.5V (which is where the number in the comment note is coming from), the point at which the current limit trips is independent of supply voltage. The voltage created on the ILIM pin by placing a resistor is instead compared across VCL(th) which is valid for all supply voltage ranges and supported temperatures.

    Your understanding of the 1.5x setpoint is correct, however another datapoint here is that the voltage drop across the FET will also play a factor here. If the voltage drop across the FET is greater than 2.5V (as it would be in a short-to-ground or capacitive inrush event)  then the current limit will trigger regardless of the 1.5x number.