all home built solar system

Author	Message
Haxby Guru Joined: 07/07/2008 Location: Australia Posts: 423	Posted: 03:34am 19 Apr 2021         poida said     Haxby said   Will there be any TVS diodes across the gates? Not needed? Or are they under the board? They are not needed. The totem pole driver on the power board is very good in insulating the problems of induced gate voltages getting to the IR21844 chips. It absorbs them easily and very little or zero ends up going back into the control board. I find this is the solution to the problem. (use totem pole drivers on the power board.) Very little if any voltages are sent back from the two transistor's base pins to the gate drive ICs. Even when delivering large power levels. The Aliexpress  power boards that use the EG002 driver modules all (except one) have the weakness that requires protection of the gate drive IC outputs. The 3 pins of the MOSFET have capacitors connecting each other. It might not seem that is the case but in the real world of electronics parasitic effects are present. When the Drain pin sees a fast changing voltage or current, the Gate pin will see a voltage spike due to the capacitive coupling of the Gate and Drain. This voltage spike can be such that once it appears on the gate drive IC output pins, it is now well below or above the specified allowable voltage. And it blows the output drive after a while. And we clean up the broken MOSFETs then. So the control electronics are safe behind the totem pole driver, but what about the MOSFET itself? The gate will have a max voltage specification around 25v which may be exceeded. Or are they sturdy enough to handle it?