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TPS1H000-Q1: TPS1H000-Q1 Current Accuracy

Ivan Liu Zhu
Prodigy 150 points
Part Number: TPS1H000-Q1

Tool/software:

Hi, 

I would like to understand better the current limit accuracy of TPS1H000-Q1 device. 

It is stated in the datasheet as +-20%:

  • Do you have a graph and minimum/maximum values for K(cl) and Vcl(th) parameters over temperature? 
  • Current limit depends on the external Rcl resistor. Does the +-20% consider the tolerance of the resistor or is +-20% assuming a nominal value?

In general I would like to understand where this tolerance is coming from and if it can be improved. 

  • 0
    TI__Mastermind 34925 points

    Ivan,

    It might be best to show you this with an example. The TPS1H000A-Q1 has a current limit accuracy of the following:

    So say we want to set the current limit to 100mA. We would first calculate the "ideal" current limit using the following formula:

    VCL(th) and KCL are constants in the datasheet and are 0.8V and 600, respectively. If we calculated for 100mA, this would give us a RCL value of 4.8kOhm, which we would put to 4.87kOhm to match a standard E96 1% tolerance resistor.

    The +/-20% number gets factored into KCL:

    Taking these values, you back calculate the minimum/maximum current limit values using the 1% resistor tolerances:

    As long as you are using the +/- % accuracy numbers listed in the datasheet, this accounts for temperature and process variation. We are also making an Excel calculator to make this a bit easier to to calculate. 

    Best Regards,
    Tim

  • 0 in reply to Timothy Logan
    Prodigy 150 points

    Thank you for the example. As I expected, Rcl tolerance impacts the overall threshold according to the equation. Also it is good to know that the variation of 20% is due to the Kcl factor. Thanks for this clarification. 

    Coming back to the 20% Kcl variation. It would be nice to see a graph how it varies over temperature. I want to understand how much this would improve if the temperatures are in between a different range, e.g., -20ºC to 60ºC. 

    When you mention process variation, how many sigmas of the whole production are covered within the +-20% of tolerance? Are we talking about 3 sigma, 6 sigma?

  • 0 in reply to Ivan Liu Zhu
    TI__Mastermind 34925 points

    Ivan,

    All of the accuracy numbers will be 6 sigma.

    There's not going to be a huge shift in variation over temperature so we do not have the characterized data over tighter temperature ranges. One thing to note is that the higher RON devices will have better current limit accuracy at lower current levels. The idea here is that you can change RON devices to match the nominal load current (and by extension current limit accuracy for levels that are applicable to your application). 

    Best Regards,
    Tim

  • 0 in reply to Timothy Logan
    Prodigy 150 points

    Do you have any device in mind?

    From your website filter I cannot find a similar device with higher Ron. The one with biggest Ron is already RPS1H000-Q1

    I am looking for:

    • high side switch 
    • With a operating voltage > 30V
    • Operating current < 100mA
    • Adjustable Current limitation should be more accurate than 20% at around 100mA. 
    • automotive qualified 
  • 0 in reply to Ivan Liu Zhu
    TI__Mastermind 34925 points

    Ivan,

    You are right in the TPS1H000A-Q1 would be the best device we would have for this loading profile. It would be 20% accuracy at 100mA so there would be no way to tighten the accuracy below what is currently specified in the datasheet.

    Best Regards,
    Tim