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TPS4H160-Q1: External current limit accuracy

user5013697
Intellectual 490 points
Part Number: TPS4H160-Q1

Hello

 

 

Would you please let me confirm the meaning about the note(2) on page 8 in the TPS4H160-q1 datasheet(Rev.c).  

 http://www.ti.com/lit/ds/symlink/tps4h160-q1.pdf

 

  

Is the meaning of note(2) correct as below?

  

"It is not meet to the current limit accuracy(±15%) on the datasheet until load current goes x1.5 larger than current limit setting."

 

  

if the meaning of above is correct, how is the minimum accuracy before load current goes x1.5 larger?

I worry about it limits on lower current than expected.

 0474.TPS4H160_External current limit accuracy.pptx

for example,

  Limit setting = 1A

  actual curent = around 500mA

 

in this case, is there a possibility that the TPS4H160 limits at around 600mA or 700mA?

 

 

 

About Upper limit also,

Are there possibility that more than +15% load current flows  continuously in case  if it never reachs x1.5 larger than limit setting?

 

for example,

  Limit setting = 1A , in this case,  Are there possibility that 1.4A current  flows  continuously until once it reach 1.5A overshoot upper limit.

 

 

at last,

Would you please explain why it cannot meet tne accuracy in case load current once reach x1.5 larger?

 

 

my customer is developing ADAS application using TPS4H160 and mass production is 2018 August.

so, We need to clarify this problem soon. Please hepl us.

 

 

Best regards

Yamane

 

  • 0
    TI__Mastermind 24740 points

    Hello,

    The current limit accuracy specification applies when the FET is in saturation region. The accuracy specification does not apply when the FET is in linear region. If the current limit is set at 1A, the accuracy +/-15% applies when the FET is in saturation region. In this region, 0.85A < current limit < 1.15A. Before reaching the current limit, the FET is in linear region and drain to source voltage Vds = Ron x IOUT. Load current increases slowly until the FET is in saturation region. Once the load current reaches 1.5 x the current limit set means 1.5A, the accuracy applies. Please check the attached illustration.

    Current limit Illustration.pptxRegards

  • 0 in reply to Mahmoud Harmouch
    Intellectual 490 points

    Hello

    Thank you for your reply,

    would you please let me know about two our concern.

    1:

    how is the minimum accuracy before load current reaches x1.5 larger?

    I worry about it limits on lower current than expected.

    for example,

     Limit setting = 1A

     actual curent = around 500mA

    in this case, is there a possibility that the TPS4H160 limits at around 600mA or 700mA?

    2:

    Are there possibility that more than +15% load current flows  continuously in case  if it never reachs x1.5 larger than limit setting?

    for example,

     Limit setting = 1A , in this case,  Are there possibility that 1.4A current  flows  continuously until once it reach 1.5A overshoot upper limit.

    Please see attached ppt file page 2 and 3.

    Current limit Illustration_2.pptx

    Best regards

    Yamane

  • 0 in reply to user5013697
    TI__Mastermind 24740 points

    Hello,

    I believe these questions were answered in my previous post. The tolerance is related to current limit setting and not the actual load current. If the current limit is set to 1A, and the load current is slowly increment:

    1- It can reach 1.4A and stays at this level in steady state

    2- Once it reaches the 1.5 x 1A, the +/-15% applies. That means the current can be between 1A x (1 -0.15) = 0.85A and 1A x (1 +0.15)= 1.15A.

    Regards

  • 0 in reply to Mahmoud Harmouch
    Intellectual 490 points
    Hello
    Thanks to your reply

    I understand that if the FET is not in saturation region, The current limit accuracy is not to meet to specification in datasheet.
    To meet the spec, it is need to reach x1.5 current setting at once.

    but please confirm the behavior when FET is in linear region.

    IS It posoble for the TPS4H160 limits the current at lower than Ilim x (1 -15%)?
    Does TPS4H160 limits the load current at lower than 0.85A in linear region? * Current Limit settiing = 1A


    Best regards
    Yamane