H Bridge, NMOS AND PMOS DRIVER

sarah kent · 2010-08-05T20:26:13+00:00

Hello All,I am tring to generate a square wave of 100KHz and 200 volts peak topeak across a resistor via H- bridge. The current could go upto 30A.I am looking into two following ways to drive the NMOS ( four NMOStransistors ) H - bridge.1.a. Using H bridge Drivers HIP4081A. I tried to look for thereplacement of HIP4081A but only found A4940 from Allegro microsystemswhich a little slower than the HIP part regarding rise and fall time.According to my understanding the Driver chip has to charge the inputcapacitance of the transistors. I am planning to use NMOS transistor(IRF540).So, according to HIP 4081A data sheet trise = 10nsec at C= 1000pF andif power supply = 50Volts (60% of 50V = 30volts) , So, I calculated(1000pF x 30V) / 10nsec = 3 Amp.The gate to source charging capacitance of IRF540 is 14nC; So, thecharging time would be(14nC x 30 V) / 3 = 140nsecs. Are my calculations accurate and inright direction?b. I calculated the same things using A4940 and found the followingresults(1000pF x 30V) / 35nsec = 857 mA(14nC x 30V) / (857mA) = 490nsec.Which proves that the A4940 is a slower part. But how will it effectthe voltage waveform across the resistive load. I meant to say whatwould be the difference between the two waveforms generated by twodifferent driver chips.Is there true replacement part available for HIP4081A. The reason forfinding the replacement for HIP4081A area. What if Intersil discontinue this part in the future.b. May be there is a cheapaer part available than HIP4081A.2. The second method is to use four NPN transitors to drive two PMOStransistors (High side) and two NMOS (Low Side) transistors.Microcontroller will provide the PWM pulses to control the 2N2222transistors. You can find the diagram at the following link.I am thinking of using 2N2222A to drive two (IRF540N) but unable tofind the PMOS equivalent of IRF540 N. Any suggestions!! Do I need themof the same ratings?Please also suggest that H - bridge driver approach is the betterapproach or the...