Pages: [1]   Go Down
Author Topic: transistor symbols  (Read 777 times)
0 Members and 1 Guest are viewing this topic.
Offline Offline
Newbie
*
Karma: 0
Posts: 17
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Ok, so I have this  transistor here which i have blown and need replaced. On the front, it reads

IRF3205
1 (diode symbol) R 119P
J3 T5

So I google IRF3205 and get a lot of results back, however, the symbols on the front never match past the 1st line. before i order 16 of these things, i need to know. Is this a problem, or should i just grab any old IRF3205? what do these symbols mean?
Thank you,
Ryan
Logged

USA
Offline Offline
God Member
*****
Karma: 14
Posts: 644
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

The "R 119P" and "J3 T5" are likely part of a manufacturing date/batch coding system.  If so I wouldn't expect them to match unless you had two parts that were made by the same company, at the same factory, on the same line, in the same batch.  As the IFR stands for a specific manufacturer, International Rectifier, any IFR3205 in the same packaging should work as a replacement.
Logged

Danger Boy
Offline Offline
Edison Member
*
Karma: 14
Posts: 1108
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

"I (diode) R" is International Rectifier's trademark.  Good way to spot their semiconductors.  I also like the stylized LT that Linear puts on their chips, another nice dead giveaway who made it.
Logged

I have only come here seeking knowledge. Things they would not teach me of in college.

Georgina Ontario
Offline Offline
Sr. Member
****
Karma: 5
Posts: 437
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Hope it's not a blown UPS...
Logged

Just another Hacker

Anaheim CA.
Offline Offline
Faraday Member
**
Karma: 47
Posts: 2930
...
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

The IRF number is a JEDEC registered part number with a published set of spec's all the rest is not applicable manufacturers batch and date code stuff...

Doc
Logged

--> WA7EMS <--
“The solution of every problem is another problem.” -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

Offline Offline
Newbie
*
Karma: 0
Posts: 17
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Thanks for the responses, they've been a lot of help.  I also have a follow up question for you. The reason I ask this in the first place is because i blew the transistors on my pwm motor controller http://www.ebay.com/itm/221001606857?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

if i put 16 of these transistors where the 8 blown ones are, will that double the capacity? also, is it doable to solder them back to back so as to make them fit in the same holes?
Logged

USA
Offline Offline
God Member
*****
Karma: 14
Posts: 644
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

if i put 16 of these transistors where the 8 blown ones are, will that double the capacity? also, is it doable to solder them back to back so as to make them fit in the same holes?

No, not in the way you apparently mean.  If you need or want a HEXFET that can handle higher voltages and/or currents you'll need to get some with higher ratings.  If, on the other hand, the reason you "blew" these parts was they got too hot, I'd advise getting heatsinks for them, there are heatsinks designed specifically for transistor packages with metal tabs.

Edit: If you want to add more output signals than the additional HEXFETs might be useful, but you'll still won't be able solder all them in on the original motor controller board.  They will have to be on a separate board that's wired to the orignal board.
« Last Edit: July 25, 2012, 09:37:30 am by Far-seeker » Logged

South Texas
Offline Offline
Edison Member
*
Karma: 8
Posts: 1025
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Think about it - if you solder them back to back half the pins will be in the wrong place - there are 3 pins - Gate, Source and Drain - if you revers one the pins would be in the wrong place. Look for a device with a higher current/wattage.
Logged

Offline Offline
Newbie
*
Karma: 0
Posts: 17
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

I think i have not adequately explained myself (btw,i blew  it because i wired it incorrectly and/or put way too much power through it, not because of heat).  I am not looking to add more output channels. The controller is rated to 45 amps of motors (peak current), i need at least 60, and would prefer some additional cushioning. If i were to wire these transistors into the board, would I end up with a board of a 90 amp capacity?
Logged

Leeds, UK
Offline Offline
Edison Member
*
Karma: 80
Posts: 1729
Once the magic blue smoke is released, it won't go back in!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Not necessarily. Unless the two transistors are perfectly matched (highly unlikely), one of the pair will end up conducting more than the other. For low power applications like driving a 1W led for example, this wouldn't be an issue as you would be operating a long way from the transistors rated current limit. However in high power applications such as this one, a lot more care is needed.

For example (and this is just a hypothetical, don't take these figures as accurate):

Say you pump 90A through the board. You have two transistor rated at 45A MAX. Transistor A has an on resistance of 0.01 Ohm, transistor B an On resistance of 0.015 Ohm.
You would have essentially a 0.006 Ohm resistor (the two in parallel), which at 90A would drop 0.54V.
Consider transistor A. You would have V/R = I = 0.54/0.01 = 54A. BOOM, that transistor overheats and blows. Then you just have transistor B. That would now take the full 90A, and BOOM it too blows.
As you can see, in this hypothetical situation, even a difference of 5 thousandths of an ohm difference is On resistance would be enough to destroy both FETs.


You would need to replace the FET with one which has a higher current rating, but with similar gate characteristics to ensure compatibility. Something like this might be a possibility:
http://uk.farnell.com/international-rectifier/auirf3305/mosfet-w-dio-n-ch-55v-140a-to220ab/dp/1865601
Or this:
http://uk.farnell.com/international-rectifier/irlb3036pbf/mosfet-n-ch-60v-195a-to220/dp/1698300
« Last Edit: July 26, 2012, 11:57:40 am by Tom Carpenter » Logged

~Tom~

USA
Offline Offline
God Member
*****
Karma: 14
Posts: 644
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

As Tom Carpenter explained you will need to get HEXFETs that are rated at least as high as the peak currents you want to control, if not somewhat higher.  Although probably the best idea would be to look for a controller board that is built to handle higher currents.  Otherwise, even if you upgrade the FETs there's still a possibility of something else failing due to the current being beyond the boards originally spec'ed current levels.  
Logged

Anaheim CA.
Offline Offline
Faraday Member
**
Karma: 47
Posts: 2930
...
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

My Idea, after having fixed several different wheel Chair motor controllers is to match the gate characteristics as closely as possible ... to the Biggest, Lowest Rdson Fet I could find that would fit in the holes and mount properly and then replace every Mosfet on the controller board.... I Never had one return to me, I was fixing them for free... Most times I even bought the parts myself.Wheel Chair motor controllers have little in the way of excess capacity as the least expensive parts are used, the design philosophy being "Just Big Enough" apparently to drive off the delivery truck... It's cheaper in the long run to put bigger parts in than it is to fix the controller again, and again (I know I did it once).

Doc
Logged

--> WA7EMS <--
“The solution of every problem is another problem.” -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

Pages: [1]   Go Up
Jump to: