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TPS53316: Overcurrent limit on high-side FET and TJ

Aaron Hsu
Intellectual 565 points
Part Number: TPS53316

HI All

Can you provide a graph of Over current limit on high-side FET vs TJ

  • +1
    TI__Genius 14876 points

    Hello Aaron,

    This is not specified for this device. Usually the current limit decreases with higher temperature, due to the higher Rdson of the sensing FET.  This also matches with the D/S values that show a lower current limit at lower Vout (which have a lower efficiency, meaning higher thermal losses).

    Let me know if you havce any further questions.

    Thanks,

    Dorian

  • 0 in reply to Dorian Brillet de Cande
    Intellectual 565 points

    Hi Dorian Brillet de Cande

    1.Your diagram is low-side FET vs high-side FET
       Am I misunderstanding?

    2.Yes, my experience is also that the limit current decreases when the temperature is high. (SENSE RDS(ON) )

    3.

    My use in condition is
    VIN=5V
    VOUT=0.95V
    FSW=1.1M HZ

    According to datasheet Figure 6 OCP is about 7.8A
    Overcurrent limit on high-side FET=6.1/6.8/7.5A in the table by
    to assess the minimum OCP 6.1/6.8=0.897
    TYP=7.8A
    MIN=7.8A*0.897=6.997A?

  • 0 in reply to Aaron Hsu
    TI__Genius 14876 points

    Hello Aaron,

    1. You are right, I thought this was two different operating conditions for the same High-side FET current limit. My Bad.

    3. I am not sure to understand what is the calculation you are doing here (ie. OCP 6.1/6.8=0.897). Could you elaborate ?

    Thanks a lot!

    Regards,
    Dorian

  • 0 in reply to Dorian Brillet de Cande
    Intellectual 565 points

    Hi Dorian Brillet de Cande

    Since I can't measure a lot, the minimum value of OCP under the conditions I use
    But it can be known from Figure 6 that TYP is about 7.8A
    In the table by the proportional relationship between MIN and TYP=6.1A/6.8A=0.897
    Let's evaluate the minimum value of OCP under the conditions I use
    7.8A * 0.897=6.997A?

  • 0 in reply to Aaron Hsu
    TI__Genius 14876 points

    Hello Aaron,

    You can use this as a rule of thumb, I would expect some variation to this wild approximation.

    Thanks,
    Dorian