If you work with voltages below +/-60V, then IRF250 and IRF250N are not a good choice. Unnecessary high voltage rating and you pay for this unnecessary property the price of a high gate charge and a poor body diode.
Note:
Especially the IRFP250 without N is a device from ice age.
Catastrophic body diode.
IMHO a device which should be avoided for class D in 2011.
Especially the IRFP250 without N is a device from ice age.
Catastrophic body diode.
IMHO a device which should be avoided for class D in 2011.
Then what do you recommend? Something not very expensive if is possible.
I`m going to work with +/- 40-50v
+/- 50 for irf540z and irf540n is absolute maximum rating, i`ll not use that rails, i`ll go with pafi recommended +- 45 vdc.
I know that +/-50v is maximum for irf540z, but my power supply will have +/-50v. That`s why i asked for another mosfet..
go for irfb4227, its hard to get in my country, damn... need to order outside maybe online ordering...
For +-50V rather use some 150V Fet, like:
IRFB4228, FDP2552, FDP2532, IRFB4321, IRFB4019 etc...
IRFB4228, FDP2552, FDP2532, IRFB4321, IRFB4019 etc...
Do It Yourself!
For any voltage:
- make a list (parametric search) of available MOSFETs with more Vdsmax than the maximal summed power supply voltage!
- keep only the lower 1 or (at most) 2 voltage category!
- keep only the ones whose Idmax is higher by 50 % then the highest possible peak current output!
- sort them by price!
- go through the list from the cheapest to the most expensive, check if Qrr is low enough (this is dependent somewhat on switching freq, specified current, supply voltage and some other factors, but generally more than 1 uC is too high)!
For high voltage (more than 200 V): diode trick, or IGBT is needed.
Everybody! We don't know what stores can you reach and what is available at the moment!
Hints:
- IRFB4xxx is a new, very good series, still not too expensive (where available).
- TO220 is cheaper than TO247 with the same chip. As a bonus, its inductance is lower also.
- If Qg is high (more than ~100 nC), use a BC327 to discharge gate!
norazmi!
IRFP4710 and IRFB4615 are both good, the first one is better for low impedance, the other is good for higher impedance and high quality.
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Have a look to the types which where proposed positively...and see the differences!
If you insist on the bold package: IRFP4321
Smaller packages:IRFB4321, IRFB4615, FDP2552
Check about values for gate charge, and for the data of the body diodes.
If these points don't tell you much, dig in the web for basics about switching MosFets. Application notes and papers from the semiconductor manufacturers are a good starting point.
Thanks Pafi, i would like to know how to setup this one as you mention, "If Qg is high (more than ~100 nC), use a BC327 to discharge gate!"
and what about totem pole discharge?
and what about totem pole discharge?
norazmi!
I'm not sure what do you mean as totem pole, but anything more complex than a pnp transistor is unneccessary, because IR2110 is strong enough to charge the gate fast enough, only the discharge needs to be made faster. Connect base to IR2110, collector to source, emitter to gate, and place Rg between emitter and base!
I'm not sure what do you mean as totem pole, but anything more complex than a pnp transistor is unneccessary, because IR2110 is strong enough to charge the gate fast enough, only the discharge needs to be made faster. Connect base to IR2110, collector to source, emitter to gate, and place Rg between emitter and base!
aight, got it Pafi, thanks for the info, i can see more improvement on the sound. 😀, btw mosfet also more cold than before.
regards
regards