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Old 11th January 2006, 09:17 PM   #1
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Default On Semi ThermalTrak

Has anybody tried the new ThermalTrak transistors from On Semiconductors? They have a diode for biasing built right into the package.
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Old 11th January 2006, 11:20 PM   #2
Stocker is offline Stocker  United States
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I was going to tell you to search, but then I did it and nobody had used them yet and reported back about it. I did find one interesting application note where the temperature monitoring was done with the inbuilt diodes in series on paralleled transistors, but that's about it.

somebody actually HAD some of these, but didn't report back what they did with them...?
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Old 11th January 2006, 11:22 PM   #3
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why not get some and have a play around uourself and see what you can get out of them? or are they stupidly expensive? they sound pretty cool though..
Owen
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Old 11th January 2006, 11:36 PM   #4
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They kind of are expensive. About $10 a piece from Digikey. Plus I don't have any equipment yet for building amps.
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Old 11th January 2006, 11:43 PM   #5
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fair enough, they are pretty expencive. They do sound pretty cool though, hopefully someone out there has played around with them, i will be keeping an eye on this thread, could turn out to be quite interesting.
Owen
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Old 11th January 2006, 11:50 PM   #6
Leolabs is offline Leolabs  Malaysia
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Sanken does manufacture those kind of transistors,should be nothing special.
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Old 11th January 2006, 11:54 PM   #7
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Heres an apllication note on using these in a power amplifier.

http://www.onsemi.com/pub/Collateral/AND8196-D.PDF
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Old 11th January 2006, 11:58 PM   #8
lineup is offline lineup  Sweden
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Interesting devices!

Diode that senses the temperature, like a transistor in a VBE multiplier,
has its own 2 pins.
So the ThermalTrak is a 5 pins device.
See attached image.
----------------------

Complementary ThermalTrak™ Transistors
NJL3281D(NPN) NJL1302D(PNP)
BIPOLAR POWER TRANSISTORS
TO-264, 0.625 °C/W
15 A, 260 V, 200 W
fT 30 MHz

http://www.onsemi.com/PowerSolutions...do?id=NJL1302D
Attached Images
File Type: png thermaltrak.png (34.1 KB, 3231 views)
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Old 12th January 2006, 12:02 AM   #9
clem_o is offline clem_o  Philippines
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Unfortunately they don't seem to be optioned for free sampling.

I wonder how well they match off with standard MJL3281/1302? Since most amplifier designers will go with a VBE multiplier (and perhaps use several output transistors in parallel), maybe it will be viable to get just one NJL device, use its thermal diode for bias tracking, and use standard MJL stuff for the rest - cost savings, assuming these transistors are reasonably matched...

Cheers!

Clem
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Old 12th January 2006, 02:03 AM   #10
anatech is offline anatech  Canada
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Hi Clem,
Good thought for a manufacturer who wants to mystify the average service person. It adds a skew to the inventory and may become unavailable. Standard methods are reliable and so most manufacturers will be reluctant to use them.

If it's needed to track temperature that closely in an amplifier, I feel it's a marginal design.

Now if a replacement from NTE shows up ... Sad state of affairs for many repair shops.

-Chris
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