Warning irs2092 and IRFB4227

[nigelwright7557]

I have advised a few people that the irs2092 will work with irfb4227's without a buffer.

I found this to be true for my first batch of boards.


On my most recent batch the dreaded 2092 "click" started on driving the amp hard.

This turned out to be the mosfets gate capacitance slowing down the mosfet switch on period.

So for even one pair of 4227's you need a gate buffer. I use the tc4420.
This seems to drive two pairs ok as well.

[ljm_ljm]

IRFB4227 large current advantage.

However, the appropriate, this field possess a greater capacity. Greater QG. Do you think its advantages where it

[MOER]

These ICs were ONLY designed to work with low gate charge FETS typically less than 35nc these ICs work fine

We use the 20957 with IRFB4227s and simp,y use totem drivers with no issues

[nigelwright7557]

I use the 4227's for the current they will pass.
I use one pair for a 500 watt amplifier into 4 ohms and two pairs for 750 watts into 2 ohms. Both amplifiers use tc4420 gate buffers.

[ChocoHolic]

Originally Posted by MOER

These ICs were ONLY designed to work with low gate charge FETS typically less than 35nc these ICs work fine

We use the 20957 with IRFB4227s and simp,y use totem drivers with no issues

...I am using the 20957 with totem drivers (FZT853 and 953) for IRFB4115 and it is working great.
Of course you do not need such high voltage BJTs, but should be fast high current switching types. FZT853 and 953 are simply in my assortment, because I do not want to store the same thing in multiple voltage levels...

[Eva]

The parasitics built into the layout matter a lot when driving MOSFET directly from such an IC. Voltage glitches due to unexpected inductances are usually the problem.

[nigelwright7557]

Originally Posted by Eva

The parasitics built into the layout matter a lot when driving MOSFET directly from such an IC. Voltage glitches due to unexpected inductances are usually the problem.

I made the pcb tracks as short and as thick as possible.
The problem was simply the irfb4227's were to capacitive at their gate for the 2092. The gate and so the mosfet switched on too slowly and the irs2092 saw this and started resetting. With the buffer the problem went away completely. The over current settings were set high so it couldnt have been an over current causing the reset.

[Eva]

Yes, but the usual ringing tail after the switching event (if not suppressed) can trigger the overcurrent protection too, or cause parasitic toggling of the comparator due to cross-talk, which severely degrades efficiency and reliability. I associate this behavior with thru-hole parts and/or not using a proper ground plane (not low enough power-to-signal cross-talk, usually appears with amplifier near clipping into low impedance). Only amplifiers free from parasitic switching can be considered reliable.

[nigelwright7557]

Originally Posted by Eva

I associate this behavior with thru-hole parts and/or not using a proper ground plane (not low enough power-to-signal cross-talk, usually appears with amplifier near clipping into low impedance).

This is what I found, the amplfier was resetting when driven hard.