Prev: Cheap Wholesale Evisu Shoes (free shipping)
Next: Instrumentation op-amp for DC-coupling to audio input?
From: Tim Williams on 13 Jul 2010 07:19
http://www.fairchildsemi.com/ds/FG%2FFGA30N120FTD.pdf

Maximum collector current 60A at 25C. I don't see any condition, taking a reasonable guess at Vce(sat) at max Tj, where this could possibly dissipate anywhere near the power rating of 339W (also at Tc = 25C). In fact, the typical output characteristics show it should be closer to Vcesat = 3V, Ic = 120A, Vg = 15V. So why pick 60A?

More BS? What's the real rating? Buy from someone else? Ha, no one else even has honest ratings...

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
From: John Larkin on 13 Jul 2010 09:58
On Tue, 13 Jul 2010 06:19:55 -0500, "Tim Williams"
<tmoranwms(a)charter.net> wrote:

>http://www.fairchildsemi.com/ds/FG%2FFGA30N120FTD.pdf
>
>Maximum collector current 60A at 25C. I don't see any condition, taking a reasonable guess at Vce(sat) at max Tj, where this could possibly dissipate anywhere near the power rating of 339W (also at Tc = 25C). In fact, the typical output characteristics show it should be closer to Vcesat = 3V, Ic = 120A, Vg = 15V. So why pick 60A?
>
>More BS? What's the real rating?

I'd go for the headline: 30 amps. That's achievable, without a lot of
switching losses or water-cooled diamond heat sinks. The 339 watts is
absurd.


>Buy from someone else? Ha, no one else even has honest ratings...
>

Looks like everybody has to keep up with IR. They should add to "Abs
max ratings"

MAXIMUM LIES 12 typ

John

From: Jan Panteltje on 13 Jul 2010 10:46
On a sunny day (Tue, 13 Jul 2010 06:19:55 -0500) it happened "Tim Williams"
<tmoranwms(a)charter.net> wrote in <AZX_n.70579$Lj2.30489(a)newsfe05.iad>:

>http://www.fairchildsemi.com/ds/FG%2FFGA30N120FTD.pdf
>
>Maximum collector current 60A at 25C.


At 20 V gate, and 60 A the drop is 2 V, so that makes 120 W.
RTjunction-case = .38 �C / W,
so it rises 45.6 �C above 25 �C, makes 70 �C junction temp.
It will be difficult to maintain 25 �C Tc, so derate for your heatsink...
Without heatsink it is 40 �C /W so it will evaporate at 60 A.
So what do you think is a reasonable heatsink?
That is the question.
Tjmax = 150, so you can, at 50 �C ambient, rise 100 �C.
RTtotal at above 120 W must then be about 0.8 �C / W.
That leaves a heatsink of .42 �C / W.
Fan? processor cooler? Heat pipes?
Ice cubes? Liquid nitrogen? - no Tc min = -�55 C.
See, it is a real world value.
Or did I goof at the math?





> I don't see any condition, taking =
>a reasonable guess at Vce(sat) at max Tj, where this could possibly =
>dissipate anywhere near the power rating of 339W (also at Tc = 25C). =
>In fact, the typical output characteristics show it should be closer to =
>Vcesat = 3V, Ic = 120A, Vg = 15V. So why pick 60A?
>
>More BS? What's the real rating? Buy from someone else? Ha, no one =
>else even has honest ratings...
>
>Tim
>
>--
>Deep Friar: a very philosophical monk.
>Website: http://webpages.charter.net/dawill/tmoranwms
>
From: Joerg on 13 Jul 2010 10:48
John Larkin wrote:
> On Tue, 13 Jul 2010 06:19:55 -0500, "Tim Williams"
> <tmoranwms(a)charter.net> wrote:
>
>> http://www.fairchildsemi.com/ds/FG%2FFGA30N120FTD.pdf
>>
>> Maximum collector current 60A at 25C. I don't see any condition, taking a reasonable guess at Vce(sat) at max Tj, where this could possibly dissipate anywhere near the power rating of 339W (also at Tc = 25C). In fact, the typical output characteristics show it should be closer to Vcesat = 3V, Ic = 120A, Vg = 15V. So why pick 60A?
>>
>> More BS? What's the real rating?
>
> I'd go for the headline: 30 amps. That's achievable, without a lot of
> switching losses or water-cooled diamond heat sinks. The 339 watts is
> absurd.
>
>
>> Buy from someone else? Ha, no one else even has honest ratings...
>>
>
> Looks like everybody has to keep up with IR. They should add to "Abs
> max ratings"
>
> MAXIMUM LIES 12 typ
>

It can get worse. I saw an audio amp in a blister pack, IIRC at a
Walmart. Said 1000 watts PMPO on the label and the power supply was a
wall wart ...

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
From: Tim Williams on 13 Jul 2010 11:02
"Jan Panteltje" <pNaonStpealmtje(a)yahoo.com> wrote in message news:i1hu8o$ctk$1(a)news.albasani.net...
> That leaves a heatsink of .42 °C / W.
> Fan? processor cooler? Heat pipes?

T_HS = 40C is pretty easy to arrange, I intend on water cooling anything this powerful.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
 |  Next  |  Last
Pages: 1 2 3 4 5
Prev: Cheap Wholesale Evisu Shoes (free shipping)
Next: Instrumentation op-amp for DC-coupling to audio input?