Class-D Amp with IRS2092

[savu]

Hello Nigel.

250Khz is a decent sw freq (most kw level amps are running @ 250Khz)

But if the IC can do 800Khz why not aim for that?

Regards,
Savu

[nigelwright7557]

Originally Posted by savu

Hello Nigel.

250Khz is a decent sw freq (most kw level amps are running @ 250Khz)

But if the IC can do 800Khz why not aim for that?

Regards,
Savu

I had problems with the 2092 and mosfets getting hot at those frequencies.

[savu]

TC4420 has 55nS propagation delay.
ZXGD3002E6 has 2nS propagation delay.

In this case you need an emitter follower. ZXGD is the way to go.
If you were to make an opto isolated drive like for example with 6N137 followed by TC4420 than using TC4420 is a must.

Regards,
Savu

[savu]

If you use DirectFet types you could reach 800khz without melting the board.

But again 400khz is more than enough.

regards,
Savu

[nigelwright7557]

TC4420 has matched 25nS rise and fall times.

The propogation delay isnt a problem as the rise and fall time are matched.

Your device as well as being faster is also cheaper by quite a bit.

[savu]

You are right.

You just convinced me to test the TC4420.

[Dzony988]

I had never build amp with IRS2092 and I wanna try to bild with it but in data sheet nothing said about some stuff that I dont understand

All question are for schematic in post 1 of this treat



- I know for that fet death time must be 40-65ns ( resistors are like on schematic, gate res 10ohm and 8.2K+3.3K) for IRFB4227
- I know too that for VSS and VAA I need resitor (5.6V drop and 10mA and 5.6V zener)

*Now tell me, what is swich freq. with resitor 510ohms beetwen two 1n capacitors amd what is wit resitor 330ohms (without trim pot)?
*How can I set gain of whole amp
*How can I desiable curent sens and overload protection or how can I set uo it for diferent powers
*Can I use this schematic with different supplay voltage (from +-40 to +-90V) with all same values of components exept part for +12V ref to VCC- and VSS-VAA resistors
*How can I use SD pin for shut down funcion ( same like on IR2110 or ???)

[CPX]

You set deadtime using your scope to avoid masive shout throught and have the best audio quality possible.Without the scope set dead time so you will have no more than 150mA at +-45 vcc quiescent current.
You change gain and switching frequency by changing the 47 kohm and 901 ohm resistors..
Put CsD pin to ground for shutdown.

Try making datasheet schematic first and see how it works, i can not answer all your questions...maybe someone who did make this amplifier will help you more.

[electron21]

welcome
Please post the PCB for this amplifier
I want to realize this amplifier
thank you

[Dzony988]

I finsish schematic with lot of help of AN-1138

I attached you schematic. Can you look it and tell me is everuthing ok, with schematic andformulas...
But I stuck with calculation for R2 and R3, also with R4 and R5

On example +-70V @ 4 ohms load
IRFB4227 (Rds 0.024 max.)
AC sine voltage 48V before clip
AC sine current 14A (if speaker imedance fall to 3.5 ohms)
*that means aprox. 7A per voltage rail

-Dead time 45nS
- Rc = 120 ohms (Swich Freq. 300Khz)
- Rin = 47K / 30 = 1.5K (Gain 30x)
- Vaa = Vss = (70 - 5) / 10mA = 6.5K 2W

Now!!!!

- R3 = 10K (1.2 / ((Id x Rds) + 0.6))) = 10k (1.2 / (7A x 0.024) + 0.6))) = 15K
*How can I calculate R2 ???? R2+R3 have to be 10K (AN-1138)

- R5 = 10K ((Itrip x Rds) / 5) = 10K ((7A x 0.024) / 5) = 0.33K = 330ohms
* that means R4 = 9.2 K (this is maybe ok)

I dont know, I did all like in AN-1138
Where is my mestake??

And yes, which PNP NPN pairs can go to buffer?


Thanks