Matching IRFP240 for Alpeh2

[Cephas]

i have a fool problems about to Matching IRFP240 for Alpeh2

for Alpeh2 have 24 pcs IRFP240(12 pcs each channel)
and each channel 6pcs(Q6-Q11) are for current source
6pcs(Q12-Q17) for output drains
total have 4 group X 6 pcs

so when i try to matching IRFP240
i need to match totally 24 pcs for nearest Vgs?
or just matching 4 group 6pcs ??

thanks,

 

[hifi]

4 groups of 6pcs will be sufficient.

/micke

 

[BrianGT]

The reason that you are matching them is because you have 2 groups of 6 devices running in parallel for each channel. It is important that the 6 devices are matched themselves, but it doesn't make much difference if the 2 groups are matched to each other.

I bought 124 IRFP240 and managed to get them matched up quite well. Most sets were well within 0.01 Vgs.

--
Brian
gte619j@prism.gatech.edu

 

[Cephas]

thanks

for parallel devices how many Vgs diff is sufficient?
and why 2 group doesn't make much difference Vgs?
how much will be sufficient?

 

[wuffwaff]

Cephas,

according to the Pass manuals up to 0,1volt will be OK.

The two groups can be as far apart as you want.

You only match the devices so that every one of them takes aprox. the same current when paralleled.

william