Mosfet Replacement Question

[mmartell]

What are the specs one looks at when looking for a replacement transistor ? I had the datasheets for both but a little overwhelming... I'm hoping I can use a 5N3011 in place of a 88N30W. Thanks

[senz_90]

Re: Mosfet Replacement Question

What are the specs one looks at when looking for a replacement transistor ? I had the datasheets for both but a little overwhelming... I'm hoping I can use a 5N3011 in place of a 88N30W. Thanks

lower rds and capacitance but the others spec need higher if i remember correctly when try to replace mosfet.

[BigPete]

Re: Mosfet Replacement Question

Hi,

Could a 88N30W transistor be used in place of a 5N3011?

5N3011 datasheet

88n30w datasheet

A lot of specs are the same but I'm not sure which are the critical ones. Voltages and amps are the same mostly but the switching times(if thats what you call it) are faster with the 88n30w. So would that mean it would work harder than the other 5 that are in parallel with it, and burn out faster?
I have a 88n30w in stock and would need to order a 5n3011.

Thanks for the help.

[stj]

Re: Mosfet Replacement Question

faster is good.
lower on-resistance is also good because it means less heat.

[redwire]

Re: Mosfet Replacement Question

The specs look very similar, I would say it's a good substitute.
The 88N30W has a bit more input capacitance (8440pf vs 5000pF) and gate-charge (170nC vs 95nC), which adds a bit of work for your gate-drive circuit. It's a small difference in a bank of 5 MOSFETS.
What are you fixing that uses this much beef?

[BigPete]

Re: Mosfet Replacement Question

Thanks for the replys.
I'm fixing an oldish 50 inch Full HD Samsung sustain board. One of the six transistors was shorted(fortunately I only had to unsolder three transistors to find it).
I just put in the 88N30W transistor and the TV fired up. So very happy.
Thanks for the quick replys.

[BigPete]

Re: Mosfet Replacement Question

Just an update.
I got this TV going with 5 5N3011 transistors and 1 88N30W transistor. TV was running mint.
A mate of mine decided he wanted to buy it.
So I thought maybe it is a good idea to replace all the 5N3011 transistors with new 88N30W ones.
The TV didn't like it and blew a transistor.
Ordering 6 new 5N3011 transistors now.

[Longbow]

Re: Mosfet Replacement Question

Thanks for your update. I think it is very helpful to realize that circuits are often designed around specific parts. Flyback circuits, SMPS circuits, etc. all depend on specific components and values. Finally, as seems to be true in this case, a number of parallel power transistors must all be the same part. I think we have all verified that fact at one time or another!

[Agent24]

Re: Mosfet Replacement Question

The 88N30W has a bit more input capacitance (8440pf vs 5000pF) and gate-charge (170nC vs 95nC), which adds a bit of work for your gate-drive circuit.

Is there a rule of thumb or such about input\output capacitance etc when doing replacements? How much of an increase or decrease is too much?

[stj]

Re: Mosfet Replacement Question

increased capacitance can reduce the switching speed.
the real lesson here is not to mix parts that operate in a parallel array.

[mmartell]

Re: Mosfet Replacement Question

Hmm I'm no electronics genius but the set ran "mint" with mixed transistors. He doesn't say where the 88N30W's came from or if they were tested before installation so it's still possible there was a dud among the last four installed.

[Agent24]

Re: Mosfet Replacement Question

Maybe the circuit was fine with just one 88N30W in the mix but couldn't handle five?