High Current Driver

D

Thread Starter

DoGer86

In need of one high and one low side big MOSFET any as IXFN132N50P3 (like this HiPerFET) 500V 18nF gate 1,16-ohm gate input resistance.


I'm thinking of using anything or something with a bigger current and simpler driver. What would you recommend for this size of MOSFET?
 
FAN7392 Data sheet on one option. This is not isolated so the controller (PWM) needs to be sitting on the Source of the bottom FET.
Do you need isolation?
View attachment 80
You do not need isolation between the controller, FAN7392 driver and the bottom side FET Q2; high side FET Q1 drive control is internally isolated in the driver itself. FET drive energy for Q1 is supplied to Cboot through Dboot when Q2 is ON. DO read the application information beginning on page 14 in the data sheet; PCB layout to minimize negative spikes on pin 5 is important. (An internal PCB ground plane can dramatically reduce circuit inductances, but are seldom used due to the extra cost.) If all else fails, a closely spaced SiC Schottky diode between pin 2 (anode) and pin 5 (cathode) would solve the negative spike problem (a fast recovery silicon diode may work too, and be lower cost).
 
You do not need isolation between the controller, FAN7392 driver and the bottom side FET Q2
I don't know if DoGer86 needs isolation or not. I asked because working right on the power line can be exciting. I am using isolation because the computer (PWM) is sitting on ground and the FETs are on the power line.
 
I don't know if DoGer86 needs isolation or not. I asked because working right on the power line can be exciting. I am using isolation because the computer (PWM) is sitting on ground and the FETs are on the power line.
I don't know if DoGer86 needs isolation or not. I asked because working right on the power line can be exciting. I am using isolation because the computer (PWM) is sitting on ground and the FETs are on the power line.
Well, yes, that does make quite a difference. Isolated communication between the controller and FET driver would then be necessary, as the driver needs direct connection to the FETs.
 
R

Russel Hobbs

Could you potentially employ a bootstrap on the high side? Basically, does the MOSFET turn off periodically and enough for the bootstrap cap to potentially recharge?
 
Bootstrap drivers are cool, as long as you don't exceed their max dv/dt. Could kill the switching node.

In my opinion, the safest and most complex option would be a fully isolated driver.
 
I have done exactly what Fletcher was talking about, I have exceeded the max dv of the bootstrap drivers, so it killed the switching node. To be honest, actually I did not want to do that. When I have mentioned that the node is down, I could not understand why as I did not try to exceed the max dv. Because of that, I had to postpone this project, as I could not find any other solutions in this case. I even called for my broker to help me out. Thankfully I offered him a letter of authority and he can do all of those things for me. If you do not know what this letter is, you could read this article https://www.simplyswitch.com/energy/guides/what-is-a-letter-of-authority/, and trust me, and it is a very useful thing! He has called almost every single energy supplier in order to find out if they could actually offer us a better energy plan and find out many other things.
 
You can augment their drive capabilities with an external current booster, or even a separate driver following the bootstrap chip.
 
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