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Mystery Siliconix Power Transistor

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Marconi_MPT4
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Having trawled through all the Siliconix data books VMOS, MOSPower from 1983, 85, 88 and 1990, I am still unable to identify Siliconix type WM360 TO-3 power transistor. The anti-static pack label suggests 1990 vintage and device has T9036 (date code?) printed below part number.

Tests performed show it appears to behave as a MOSFET as the gate can be biased on and there is a near short circuit measured between Drain and Source in both directions. This condition persists until the gate is discharged.

Any ideas on what it might be?

Cheers
Rich

 
Posted : 14/04/2014 12:54 am
Refugee
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It is most likely to be an audio MOSFET.
Link G to S and connect a DVM across it and show it a Megger. It will act like a zena diode at about twice the VGS rating.

 
Posted : 14/04/2014 3:42 am
Anonymous
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The background is insert of "History of Fairport Convention"? Not sure as I had to leave mine behind in 1975 or 1990.

Perhaps the Transistor is a Power Mosfet with OEM/Customer code.

 
Posted : 14/04/2014 9:02 am
Marconi_MPT4
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The background is insert of "History of Fairport Convention"? .

Got it in one! I was having a chill out session with some old vinyl and Fairport sleeve was on the desk. Sandy Denny singing 'A sailors life' has never been bettered....

Given there is very little in the way of information on this device, I am beginning to think it may be an OEM part.

It is most likely to be an audio MOSFET.
Link G to S and connect a DVM across it and show it a Megger. It will act like a zena diode at about twice the VGS rating.

It is possible so will do a bit more testing.

Cheers
Rich

 
Posted : 14/04/2014 6:42 pm
Red_to_Black
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I found this, if it is any help ?

http://www.alibaba.com/product-detail/- ... 92078.html

Of course I cannot verify any of the data contained.

 
Posted : 14/04/2014 6:59 pm
Marconi_MPT4
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Of course I cannot verify any of the data contained.

Thanks for link, interestingly puzzling specs. Input impedance is quoted at 1.5Mohms with a bias current of 400nA suggesting a bias voltage of 0.6V which they also state is in the range of -35V to +270V. Power dissipation is quoted at 0.021 to 1.05 W, I would expect a TO-3 device to be in the region of 100 to 150W at ambient. Operating temp quoted at -110 to 198 C which exceeds the upper limit of silicon by some margin, so right to be cautious in trusting validity!

Findings so far suggest the WM360 is either a MOSFET or IGBT. With my limited equipment it has an un-measurable input impedance between, lets call them notionally, gate and source. A diode can be measured between source and drain which could be the parasitic diode found in most MOSFET transistors. I checked an IRF3205 N-channel fet and found this also had the same topology.

In practice I think it may be difficult to discern if this is an IGBT or MOSFET just from simple analysis.

A little bit more testing is needed I think.

Cheers
Rich

 
Posted : 15/04/2014 1:16 am
Refugee
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That data is very vague as it is being supplied by some company that is selling them.

 
Posted : 15/04/2014 1:34 am
Red_to_Black
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If you type the WM360 into the alibaba site it comes up with various device ratings and types, I actually wondered if it was possibly lost in translation somewhere a long the lines, given most that of the suppliers seem to be based in China.

Almost all searches for that type number seem to come up as pages of various languages of the same alibaba site.

Not much help I know. :bbd

 
Posted : 15/04/2014 1:38 am
Marconi_MPT4
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I have noticed on these Chinese sites, that for a product 25 years old, they will supply as many as required on request. Interesting since the data sheet is surprisingly scarce and Siliconix have been part of Vishay for just as long. I would be surprised if they were genuine NOS product.

Today I set up two power supplies, one connected between drain and source set for 20V, current limited to 0.5A. Another connected between gate and source with positive to gate via 10k resistor [note], current limited to 100mA adjustable from 0 to 30V.

With gate voltage set to 0V the drain current was zero. Slowly adjusting the voltage upwards, drain current started at 0.1A when Vgs was 2.2V. Increasing gate voltage further increased drain current until at around 4.0V the FET was fully enhanced with Ids at 0.5A, Vds < 0.1V. With a low Vgs threshold it looks as if this device might be designed to interface at 5V TTL levels.

Next test will be to ascertain the drain to source avalanche voltage.

[note] without 10k stopper resistor this device burst into oscillation!

Rich

 
Posted : 15/04/2014 10:37 pm
Refugee
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That is looking more and more like a FET with plenty of gain.

 
Posted : 15/04/2014 11:41 pm
Marconi_MPT4
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...Next test will be to ascertain the drain to source avalanche voltage...
Rich

With gate and source shorted, the drain-source avalanche voltage measured at just over 70 Volts. In practice the rule of thumb is that avalanche voltage is roughly 1.3 times operating voltage, suggesting this device is rated at 55-60V.

Perhaps the type number provides a clue in that WM360 might suggest 3A or 60V operation within power rating.

At some point I am going to plot the characteristic curves using a National Instruments USB DAQ borrowed from a mate. Some level shifting circuitry has to be built first for control over power supply settings and test software written to simply set test voltages, read current and write data to a disc file for later plotting.

Rich

 
Posted : 25/04/2014 3:37 pm
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