HI Bruce,Frank and anyone else interested..

I have been looking around for the spice files, etc. I easily found my STP11NM80 spice model on the ST site, but Fairchild doesn't have data published on the FQA11N90 that I can find..

Here is the stuff I found:

nice articles on the Infineon site on modeling FETS

http://www.infineon.com/cms/en/product/ ... all+groupshttp://www.infineon.com/dgdl/an_psm3e.p ... 0a482e04ebST site articles and spice data for their FETs:

http://www.st.com/stonline/products/fam ... ircuit.htmhttp://www.st.com/stonline/books/pdf/docs/3674.pdfHere is a text model of the STW12NK90Z, which is sold as a replacement for the FQA11N90, but that doesn't mean it is the same exactly, but should be close anyway. ST is much better at providing this kind of data, unless I am missing it at Fairchild's site.

* MODELLING FOR STW12NK90Z

.SUBCKT STW12NK90Z 1 2 3

LG 2 4 7.5n

LS 12 3 7.5n

LD 6 1 4.5n

RG 4 5 1.995

RS 9 12 0.172E-02

RD 7 6 0.516

RJ 8 7 0.574E-02

CGS 5 9 0.323E-08

CGD 7 10 0.445E-08

CK 11 7 0.559E-10

DGD 11 7 DGD

DBS 12 6 DBS

DBD 9 7 DBD

MOS 13 5 9 9 MOS L=1u W=1u

E1 10 5 101 0 1

E2 11 5 102 0 1

E3 8 13 POLY(2) 6 8 6 12 0 0 0 0 0.299E-01

G1 0 100 7 5 1u

D1 100 101 DID

D2 102 100 DID

R1 101 0 1MEG

R2 102 0 1MEG

.ENDS STW12NK90Z

.MODEL MOS NMOS

+ LEVEL = 3

+ VTO = 4.542

+ PHI = 1.018

+ IS = 0.1E-12

+ JS = 0

+ THETA = 0.789E-01

+ KP = 13.738

.MODEL DGD D

+ IS = 0.1E-12

+ CJO = 0.156E-10

+ VJ = 0.709

+ M = 0.339

.MODEL DBD D

+ IS = 0.1E-12

+ CJO = 0.147E-10

+ VJ = 0.779

+ M = 0.335

.MODEL DBS D

+ IS = 0.1E-12

+ BV = 969

+ N = 1

+ TT = 0.964E-06

+ RS = 0.559E-02

.MODEL DID D

+ IS = 0.01E-12

+ RS = 0

+ BV = 979

* END OF MODELLING

Fairchild has some spice models for some FETs, but not the FQA11N90. I tried to find an easy way to email them and ask for it but could not easily find an email address. Not a very friendly website for engineers.... ST much better in terms of supplying data, etc.

Here is a search result on Fairchild's site on Spice modeling:

http://www.fairchildsemi.com/sitesearch ... ender=1&w=I guess we can read their articles and read ST articles on the models and see how they might be used together, or just use the ST equivalents if you actually want to know the real data on them....

Mike