Current capacity

Non-trivial to determine (and temperature-dependent).

The current to actually melt a copper wire of that cross section (long and without heat sinking) is in the 50A range.

Some data sheets say 75A (presumably under improbable conditions).

Probably 30A-40A is sort-of safe.

Best regards, Spehro Pefhany

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Never did this before but convert it to a wire gauge and use the AWG wire chart......

0.029 x 0.031 inches 29 x 31 mils = 899 square mils x 4 / Pi = 1144.64 circular mils

Between 10 and 9 AWG (closer to 10AWG) ~15A a conservative rating.

!Fusing current is 333 A

Your PCB Traces are probably the limiting factor.

Cheers

Hmm, I use 10AWG for 30A. 15A is quite conservative!

And that's for long lengths, cylindrical cross section, wrapped in insulation -- the flattened leads will be somewhat less conductive lengthwise (= slightly harder for the component body and PCB to sink heat from the middle of the leads), but the increased surface area, bare metal, and undefined temperature rating (not limited by insulation breakdown) mean it should handle more like 60A quite easily.

For practical purposes, I limit my use of TO-220 at 50A and as many watts, and TO-247 at 100W and A.

Tim

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Website: http://webpages.charter.net/dawill/tmoranwms

1144 circular mils is more like AWG 20, which has a fusing current of 58A.

Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

6 to 8 amps continuous , wire bond in part limits, also lands to lead

The limit occurs in the wire-bond of the TO220 part, not the conductors themselves.

RL

"The conductors" are referred to by the industry as "the lead frame"

and is typically a plated copper media stamped out. around which the plastic package is molded. The device die itself is bonded to the lead frame for heat sinking/migration purpose. The CONNECTIONS to the elements on the die, whether it is a diode, transistor, or other multi-connection device menagere,are made by bond wire. Used to be Aluminum. For power packages, many in parallel are used. The plastic case then gets molded around it.

The current bottleneck is indeed in the wires that attach the device element on the die to the device LEGS on the lead frame. Their attach points are the actual weak point,Once one goes,the rest go like a zipper.

That is why they usually put so many (wire bonds) down on high power devices,so the device will fail before the connection mechanics.

And 30 A on a PWB trace is already difficult to manage.

?-)