3525 PWM - soft start quastion ?

[Astro Power]

i want to build with the 3525 Ship PWM to turn on a DC moror,

i have the circuit, Pin 8 is a "soft start",
how can i control on the soft start time ?,

In all the websites i see the Pin 8 is connect to 10uF/100uF and to the Zero.
but no mention for the soft start time calculation.

i need the soft start (from 0% to 50% duty cycle) will be in 2-3 Seconds.

Can you help me please to figure it out ?

the motor maximum draw is 38A, i think about 4xIRFZ44, it is good enough?

Thank you,
Tamir

[N-Channel]

Astro-

Try looking at ONSemi's website. The SG3525's datasheet should have the plug-n-play equation for calculating softstart cap value for a desired softstart time. Typical cap values are 2.2uF to 10uF.