Newsgroups: comp.robotics
Path: brunix!sgiblab!zaphod.mps.ohio-state.edu!darwin.sura.net!news-feed-1.peachnet.edu!umn.edu!staff.tc.umn.edu!rogers
From: rogers@staff.tc.umn.edu ()
Subject: Re: ==]  MOSFET help for steppers...
Message-ID: <C5rC83.111@news2.cis.umn.edu>
Sender: news@news2.cis.umn.edu (Usenet News Administration)
Nntp-Posting-Host: staff.tc.umn.edu
Organization: University of Minnesota
References: <gJFZ2B1w165w@inqmind.bison.mb.ca> <lsr9d9INN11d@exodus.Eng.Sun.COM>
Date: Tue, 20 Apr 1993 01:02:25 GMT
Lines: 42

In article <lsr9d9INN11d@exodus.Eng.Sun.COM> cmcmanis@yikes.Eng.Sun.COM (Chuck McManis) writes:
>In article <gJFZ2B1w165w@inqmind.bison.mb.ca> (Baden de Bari) writes:
>> ... I was wondering if there was a high-voltage capable and oh, 2-3a
>> ic avail like the 4007 or 14007 that would have several mosfets on it.
> 
>Yup, Call up your local Texas Instruments distributer and ask them for
>samples and information on the TI TPIC2701N which is a 16 pin DIP package
>with 7 MOSFETs in it (you'd need 4 obviously) and they claim that the
>price is $1.85 in 1000s so figure $4-$5 in small quantities. If you call
>them at 1-800-477-8924 ext 3438 they will send you some as well.
>
>These can carry 7.5A continuous, have a .5 ohm on resistance and no
>doubt need to be heatsinked.
>--Chuck

Well, the first part is right but the 7.5 A figure is for the single and
dual models in a to-220 (big rectangle with a bolt hole for heat sink)

The 7-MOSFET part, the tpic2701 is only good for 3 A peak, .5 amp continuous
and thats just on one channel at a time.  The dip package can only dissapate
something like a 1.5 W.  I liked the looks of this at first but after looking
closer at the specs I found it doesnt have enough umph to drive the steppers
we use.

I have found really nice MOSFETs in a to-92 package (plain 2n2222 transitor
package) from a place called supertex.  call them for there catalog.

  ZETEX has these little descrete MOSFETS also, but not as low RDS on as
supertex (RDS = on resistance, the lower the better, the more power,
the more money).  Some ZETEX parts are listed in the digikey catalog.

For BIG MOSFETs look at the Phillips power MOSFETs in the Digikey catalog.
Pretty inexpensive.  A MTP3055 replacement is 1.01 in 1' quantity 
(.1 Ohm RDS on, 75W max dissipation). part number=BUK453-50
The big mother is the BUK456-50 with .028 RDS on for only $2.60 in 1's
Q., big enough to handle a one hell of a motor.

Brynn

rogers@staff.tc.umn.edu   


