I want to make a MOSFET switch to drive a 12 V 300 W heat bed. Instead of buying one, I decided to make myself one. I used IRF48N MOSFET and FAN7392 Mosfet driver to make circuit and when tested it, it worked(I tested it by heating a 40 W hotend). I later had to solder few male header pins to provide connections for FAN to cool the MOSFET & Heat sink. Then when I tried to heat the hotend, it's not working(May be I damaged it when soldering).
This is my current circuit
I think I damaged the FAN7392. With input from Arduino, LO pin should give 12 V to turn the MOSFET ON, but now its not. I don't know how it damaged, but I'm little skeptical of my circuit.
One guy suggested me to
add capacitor to the supply pins(when checked the datasheet of FAN7391, it says that, my mistake)
Add a Zener voltage protection to MOSFET gate
Don't leave any pins left floating
Based on this I made following modifications
Not tried the circuit yet(need to source components).
Q1. What should be the value of capacitor? 1 micro-farad ? Is it always necessary even if the supply to driver is a regulated one?
Q2. 12 V zener for protection
Q3. Should I use pull-up or pull down for unused pins?
Q4. Do I need to make any additional modifications?
Q5. Which graph or table to give more importance when designing Switch? I mean required gate voltage to create channel for specific current. I came up with 12 V for Gate from Rds ON value and Vds vs ID characteristics