Automatic MOSFET load switch

[lemon14899]

Hello, would this design work as a self-operated load switch for both positive and negative supply rails of a RS-15-12 SMPS? (Apologies for formatting, it is my first post here)

It is partially based on this design from ROHM Semiconductorlinkomitting Q2 and returning R2 to ground, and adjusted for Vgs of both MOSFETs(enhancement type).

From my understanding, capacitor C10 from my design charges up with the initial start current. Then, when it is fully charged, power starts increasing into R9, forming a voltage divider with R10 to hold the gate of the FET at 10V, allowing power to flow. This is then returned to ground(repeated for the opposite polarity).

A few questions:

1. Is it possible to use a polarized capacitor for C9-C10? 100uF capacitors are somewhat difficult to find as NP types. (Modelling this with LTSpice gives a relatively flat response, compared to the spiky responses of lower capacitances, i.e. 560nF, 220nF, etc)

2. Is the negative load switch configured correctly(regarding polarity and mirroring compared to the positive rail version)?

Help would be greatly appreciated.

[Wawa]

I assume you want to reduce inrush current of a device connected to the Vout terminals.

The positive supply should have a P-channel fet, with source connected to Vin.
The resistors can be in the 100k or more range, making the capacitor also a lot smaller.

The negative supply should have an N-channel fet, with source connected to -Vin.
You should draw it as an exact mirror image of the top fet, but upside-down.

There should at least be 8volt across the source/gate resistor after charging of the cap.
Leo..