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Electronics => Projects, Designs, and Technical Stuff => Topic started by: aless2056 on April 21, 2022, 06:25:49 pm

Title: KA3525/SG3525 - Capacitor Softstart
Post by: aless2056 on April 21, 2022, 06:25:49 pm

Guys, if I don't use pin 8 of the SG3525 (softstart function) should I leave it open or grounded?

Title: Re: KA3525/SG3525 - Capacitor Softstart
Post by: strawberry on April 21, 2022, 06:55:04 pm

floating
grounded will shutdown (0 PWM)
https://www.onsemi.com/pdf/datasheet/sg3525a-d.pdf (https://www.onsemi.com/pdf/datasheet/sg3525a-d.pdf)

Title: Re: KA3525/SG3525 - Capacitor Softstart
Post by: aless2056 on April 22, 2022, 01:05:55 am

I once saw a circuit in which there was a resistor with a value of 10K between pin 8 (softstart) and pin 16 (Vref). I spent weeks wondering why the use of this resistor, I could never understand. Does anyone have the idea why they put such a resistor?

Title: Re: KA3525/SG3525 - Capacitor Softstart
Post by: strawberry on April 22, 2022, 04:07:19 am

internal pull up current source might not be enough in some case for noise immunity