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TPS543C20A: A couple of general questions

Kazuhiko Hirano
Genius 15078 points
Part Number: TPS543C20A

Hello,

 

I have a couple of questions about TPS543C20A as follows.

 

Q1:

Datasheet says KIND must be kept between 0.1 and 0.3 for balanced performance.

However, KIND can be 0 – 200% at WeBench.

If KIND is > 0.3, for example KIND is 2.0, what would be wrong?

 

Q2:

IOCP is defined as the valley inductor current?

So, actual maximum DC current limit is IOCP + 1/2*(Inductor current ripple)?

 

Best regards,

 

K.Hirano

  • 0
    TI__Genius 17905 points

    Hi Hirano-san,

    A1:
    Higher Kind, or lower inductor value, is often desirable to allow a physically smaller inductor to be chosen and to improve transient response, since it is easier to slew the inductor current in response to a load transient step with lower inductance. However, lowering the inductance increases the inductor current ripple which will lead to higher output voltage ripple and require more output capacitance to reduce. In addition, the higher inductor current ripple can mean higher AC/core losses, though that may be offset by the lower DCR of smaller inductance. The inductance also shouldn't be so small that the peak current hits the fixed high-side short circuit protection fault threshold (IHSOC) and negative valley current limit (IOCP_N) in normal conditions.

    A2:
    IOCP is defined for average inductor current, not valley current, at which OCP will trigger. Equation 3 is subtracting half the inductor current ripple from the peak current limit defined by RILIM resistor.

    Regards,
    Kris