looking for specific bjt - Page 1
Forum section: electronics / general

author: LaserTazerPhaser
author_rank: Regular Contributor
timestamp: December 13, 2018, 08:37:52 am
content: what bjts come in to220 with very low thermal resistance between junction and case? Im looking for sub 1 C/W parts.

author: Benta
author_rank: Super Contributor
timestamp: December 13, 2018, 04:34:11 pm
content: Quote from: LaserTazerPhaser on December 13, 2018, 08:37:52 amExtremely few, I know of none. Does it have to be TO-220? TO-3P or TO-247 would be a better choice if you have space.

author: SeanB
author_rank: Super Contributor
timestamp: December 13, 2018, 07:17:14 pm
content: Pretty much sure almost no commonly available TO220 parts come under 1C/W junction to case, except for some really exotic parts with large dies inside and pure copper base plates, with silver solder joining them. Most with that spec in common production will be larger packages like TO3P or TO247, and for the really low values you are stuck with plain TO3 or the larger block types, which can be low enough simply because the contact area is so large and you can fit a decent heat spreader plate onto the die to get good conduction to the case.Looking on Farnell the only one in TO220 with 1c/w junction to case is the Bu323Z, which has had the TO220 variant discontinued, probably because they kept blowing up when driven to the limits.http://www.farnell.com/datasheets/1916279.pdf

author: tpowell1830
author_rank: Frequent Contributor
timestamp: December 13, 2018, 07:34:35 pm
content: I am not sure if I am reading this correctly, but these old TO220s that I use very often look like they will do the job. However, they are Darlingtons with a gain of 1000.https://www.mouser.com/ds/2/149/TIP120-890130.pdfLet me know if I am reading the datasheet wrong.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 13, 2018, 08:44:09 pm
content: Look for big die parts: lots of amps, linear application.If you are strapped for cost, or capacitance or other constraints, you may not have much room to negotiate.If this is a design question, consider using multiple in parallel, or MOSFETs.Tim

author: MK14
author_rank: Super Contributor
timestamp: December 13, 2018, 10:04:11 pm
content: Quote from: LaserTazerPhaser on December 13, 2018, 08:37:52 amThis obsolete one, seems to be 0.85 deg C/W Junction to Case.BUH150, Description: TRANS NPN 700V 15A TO-220ABDetailed Description: Bipolar (BJT) Transistor NPN 700V 15A 23MHz 150W Through Hole TO-220ABhttps://www.onsemi.com/pub/Collateral/BUH150-D.PDFAnother part, apparently still in production, seems to be 1 deg C/W Junction to Case.MJE18008G, Description: TRANS NPN 450V 8A TO220ABhttps://www.onsemi.com/pub/Collateral/MJE18008-D.PDF

author: LaserTazerPhaser
author_rank: Regular Contributor
timestamp: December 13, 2018, 11:49:14 pm
content: To247/264 are expensive packages yet you can get fakes for about the same price as to92 packaged parts off ebay and aliexpress. It must be the die size which raises cost and those inexpensive iterations from ebay and aliexpress are unlikely to feature large dies infact they might even have to92 dies or something slightly larger.

author: OwO
author_rank: Super Contributor
timestamp: December 14, 2018, 07:26:58 am
content: Not a BJT but the IRF2804 has 0.5 C/W thermal resistance in a TO220 package, so it seems possible.

author: David Hess
author_rank: Super Contributor
timestamp: December 14, 2018, 11:21:29 am
content: International Rectifier used to advertise about their special TO-220 package which could hold a larger die for higher power and lower junction-to-case thermal resistance. If you inspect the back of the package, you can see that the metal part of the lead frame takes up more area with less clearance on the sides of the plastic encapsulation.I do not know if anybody ever bothered to make bipolar transistors like that. The D44VH10/D45VH10 is 83 watts and 1.8C/W which is consistent with the results IR got with a larger die. Essentially you are looking for a 150 watt or greater power transistor.