MPQ4317GRE-AEC1 SS Voltage

[sh_im]

Hi,

What is the voltage applied to the SS pin of this device?

In the reference schematic of the EVB datasheet, a capacitor with a 25V voltage rating is used. I am wondering if there is a specific reason for selecting a 25V-rated capacitor

[Rubas.FAE]

Hi @sh_im ,

Apologies for the late reply; MPS had a company shutdown for the holidays. The SS (soft-start) pin has an absolute max rating of 5.5V, but you do not directly apply voltage to the SS pin. A capacitor (Css) is connected from SS to GND, and an internal 13uA current source charges Css at start-up. The voltage seen at SS pin is the voltage of Css.

SS, FB, and EA block:

More info on SS from datasheet:

Thanks,
Rubas

[sh_im]

Hi, Rubas,

Thank you for your response.
I have an additional question: could you please explain why a capacitor with a 25V voltage rating is used?

Is it because the SS pin has an absolute maximum rating of 5.5V?

[Rubas.FAE]

Hi @sh_im ,

A capacitor with 25V rating was most likely chosen by preference for its high voltage rating relative to the SS pin 5.5V absolute max rating. You can choose a lower voltage rating, but I recommend the capacitor having at least 10V rating (~twice the SS pin max rating).

Thanks,
Rubas

[sh_im]

Thank you for your response. Although it’s a bit late, Happy New Year! Wishing you and your team continued success and good health in 2026.