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Original question:

TPS25927: Current limit precision

TPS25927: Accuracy - Figure 20 of the datasheet.

Dmitri Ivanov
Prodigy 150 points
Part Number: TPS25927

Hello,

I would like to get a better understanding of the accuracy given in the figure 20 of the TPS25927 datasheet: is it accuracy of one/multiple samples at the exact condition of

"TJ = 25°C, VVIN = 12 V, VEN/UVLO = 2 V, RILIM = 100 kΩ, CVIN = 0.1 μF, COUT = 1 μF, CdVdT = OPEN (unless stated otherwise)"

OR 

Is it the expected accuracy over a specified/full temperature/voltage/process span? 

How large accuracy spread in different samples could one expect working at a voltage of 6-9 V in the temperature span of 10 - 60 degC? 

Best Regards

DI 

  • 0
    TI__Guru 57737 points
    Hi Dmitri,

    Yes, as mentioned in the Y-axis of the graph, the accuracy is across Process, Voltage and Temperature.
    Can you let us know the reason why you need accuracy across tighter voltage and temperature spec ? Also, what is your overload current limit?
  • 0 in reply to Praveen GD
    Prodigy 150 points
    Hello and thank you,

    Do you have specifications across which Process, Voltage and Temperature spans the graph is plotted?

    The overload current limit is currently just above 2 A. We would like to know if the limit will vary as much as +/-15% in our application.

    Best Regards,

    DI
  • 0 in reply to Praveen GD
    Prodigy 150 points
    I also have an additional follow-up question:

    If the ILIM is set to 2 A and the current in the circuit reaches, let's say 2.4 A during transient event, how long time will it be before the current is limited? Do you have a typical graph for similiar scenario? Datasheet only seems to specify the trip time for fast-trip 160% ILIM.

    Best Regards,

    Dmitir Ivanov
  • 0 in reply to Dmitri Ivanov
    TI__Guru 57737 points
    Hi Dmitir,

    The Voltage and temperature across which the graph is plotted are across recommended operating conditions. You can refer to section 6.3 in datasheet.
    If you set ILIM to 2 A and a 2.4 A is drawn , the device clamps the current to 2 A as long as it does not hit thermal shutdown. How fast a transient current are you expecting ?
  • 0 in reply to Praveen GD
    Prodigy 150 points

    Thank you for your reply. 

    I did a measurement and concluded that in a similiar scenario, when the current goes up above the limit, the circuit limits the current  after around 1 ms. Yellow graph in the picture below shows the current, 400 mA / square.