The simple way to improve the IRS2092 amp performance

[authlxl]

I think lots of friends using irs2092 amp some years.

We have use it in some type amp,bass well,sound intelligibility not good,how to improve this.

Maybe we will increase osc frequency,but when we increase it more than 500Khz we will meet mosfet heat loss increase and frequently protection or other problems.

Special schottky mosfet is easy way to make it reality,but high cost and no more choice are the most direct concern.

We have test many times ,at last we found one simple way to improve it performance and using common MOSFET.


1.COMMON MOSFET @ 540Khz
2.DT TIME @ 45ns


Pls find the schematic below,we have use this schematic in our 600W/4ohm amp .works well at 540KHZ and DT set as 45ns.

When we shorted the added diode ,the mosfet heat quickly ,we have to increase DT time (>100ns)to cool it .

But when we use this circuit ,it can works well at 540KHZ(osc frequency) and 45ns (DT time) and 600W(rated power <1%thd+n).

So we call it IRS2092 FAST AMP!

Simple way,Share with diyaudio member

[Pafi]

Do you refer to D4, D6, D8, D9? This is a general, well-known solution for disabling slow body diode, not specially related to IR2092.

[Eva]

This is a classic approach often used with old and/or >200V MOSFET having high Qrr body diodes and not low enough Rds-on. Switching losses are reduced, but conduction losses increase.

Newer MOSFET up to 200V (like IRFB4227) can work "cool" without the diodes and without the dead time (I'm not sure whether this can be done with IRS2092).

[authlxl]

We have test many times,Irfb4227 and 4229 will good performance in this topology.

the DT time can decrease 1/2 when in this circuit,I use irfb4227 at 600W board,dt set 75ns,the mosfet hot quickly,from normal to 90oc at rated power.but in this circuit,dt at 45 ns,same frequency,same condition,mosfet body tempreture only increase 20oc.

I suggest friends can discuss The diode choice .we use 40A ultrafast diode,

mosfet is irfb4227.

[andrewlebon]

hi authxl
greetings is this schematic for diyers can you give part no of 40 ampere ultrafast
diode
thanking you
andrew lebon

[authlxl]

Originally Posted by andrewlebon

hi authxl
greetings is this schematic for diyers can you give part no of 40 ampere ultrafast
diode
thanking you
andrew lebon

Oh!

we parallel two 20A diode in the circuit.one thing maybe careful ,postive diode is schottky ,not ultralfast diode.if the current not enough ,you can parallel some.


Idea come from QSC PL380, Irfb4227 series schottky mosfet circuit suitable.

performance observably improved .

[Eva]

With IRFB4227 diodes are not needed at all, these MOSFET can work alone and free of body diode conduction up to 20A peak drain current, provided that proper gate drive timing is used. What I do with IR2110 may not be possible with IRS2092, as I pointed out early.

In other words, with these MOSFET only sub-optimal circuits will benefit from the diodes.

[authlxl]

Originally Posted by Eva

With IRFB4227 diodes are not needed at all, these MOSFET can work alone and free of body diode conduction up to 20A peak drain current, provided that proper gate drive timing is used. What I do with IR2110 may not be possible with IRS2092, as I pointed out early.

In other words, with these MOSFET only sub-optimal circuits will benefit from the diodes.

I suggest friends can try it or use data to prove useless or usful.

IRF4229 body diode 190ns,common ultral fast diode trr time 45ns,schocttky diode positive voltage 0.7V,no reverse time .

As engineer need try it and calculate than reason out a conclusion.

I try it once time just ago,my conclusion is right,very useful circuit.

I never try the irfb6648 or others,maybe will better.this conclusion is base on irfb4229 or irfb4227.

Driver engine is important indeed.

[Eva]

First picture: Full bridge with IRFB4227 pairs. No heatsink. Supply voltage reduced to 85V DC to cut losses (normally 170V).

Second picture: 500W into 3.8 ohm according to Valhalla power meter.

I only pushed it to the point where keeping my finger on one of the pairs of IRFB4227 through a silicone pad started to become a bit uncomfortable. Current sharing is not optimal at all because there is no thermal tracking between pairs of MOSFET due to the lack of heatsink, so one pair tends to be hotter than the rest. I didn't want to push this prototype further, as I must ship it to my customer before 13:00 and I can't afford damaging it.

It does nearly full music output into 8 ohm and 4 ohm without heatsink.

No diodes used. They won't improve it. No dead time used either

[authlxl]

Looks nice,tell us your osc frequency and output THD+N and rating power.
if the osc frequency so lower,we will careless about it.

No dead time ?is the topology not full bridge?