We are designing a buck using discretes. I have a problem with OFF time of Control MOSFET(U1) and driver(T1). In OFF time, Gate of U1 is rising very slowly to 12V which makes U1 always ON. Which in turn makes output to 12V always.
I have seen few BJT Totem pole drivers for p-MOSFET. But, i want to use this same circuit. any modification suggested so, that we can make U1 gate to rise faster.
VG1 is 1.8V,100K, 50% duty cycle square wave.
I tried to change the R1 2K to 500 and VG1 1.8V,90K,50% and found.
How to still make the Turn OFF of T1 fast, so, that Vgate of U1 rises to 12V very quickly.
I have changed the 2k to 0.5k and i am getting FET swtiched OFF and getting 5V output as intended, but Switching frequenxy is very less close to 80K and it is not following Buck formula Duty cycle ~ Vout/Vin. As OFF time has notches and slow. Any tweaks we can do on the same circuit to make it more faster. ....