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TPS62933: Phase margin and Peak Current question of TPS62933

Part Number: TPS62933

Tool/software:

Hello, TI members.

Happy new year.

I am using TPS62933 for small servo motor. (5V, 3A motor)

And I have some questions about current and output capacitor.

Need some teaching for Power novice.

.

1.  What is the allowable peak current of TPS62933?


In the datasheet, TPS62933's Iout Max is 3A,  Ihs_Limit min is 4.2A, Ils_Limit min is 2.9A.

When motor runs, Peak current of Iout(Motor) is about 2.8A. (very short time)
and when measured Inductor current are as below. 

Inductor Peak is 3.6A

Inductor RMS is 2.8A

Inductor Min is 1.8A.

.

Are each spec is related as follows? I wonder my measured values ​​are okay..


Ihs_Limit 4.2A Inductor Peak current 3.6A?

Iout Max 3A   Inductor RMS current? 2.8A

Ihs_Limit 2.9A  →  Inductor min current? 1.8A 

.

2. For using motor, I used large capacitor about 250uF~300uF to prevent motor back emf. 

But when I used webench designer,

it says too much output capacitor will make phase margin too low. (Spec is under 35 degree)
What problems arise when the phase margin is small? 

If phase margin is about 30degree, Could this cause serious problems?

Thanks.