General purpose NPN / PNP transistors >= 500mA

The BC547's complement is the BC557.

Graham

Graham's suggestion is good, roxlu, those two parts are true jellybeans. But for 500mA and up, while still in the convenient TO-92 package size, I suggest you choose parts from the Zetex E-line. DigiKey is a good source.

I also found the bc337 NPN (max 800mA) bc327 PNP (also max 800mA)

I want to use them for multiplexing LEDs with around the 32 rows and 16 columns, will those do for that when I limit the current for the columns so that it will be max

Gr. Roxlu

John Fields schreef:

If that's continuous duty they will become quite hot. Vce sat can be more than half a volt at 800mA. Operating something at the absolute maximum ratings is something I don't do in a design.

Also, don't expect a lot of current gain at those load levels. Can't you use FETs?

I like BCX70/71 as standard gumdrops, for their fantastic betas, but they're only rated for 200 mA.

John

I've been having good luck with BD135/BD136, suggested by others here a year or two ago. In my application I only push about 200mA through them at most, but they're rated to 1.5A and the TO126 case will dissipate somewhat more heat than a TO92 would, while still being smaller than a TO220. They come in various beta selections.

It's a shame there's not more stuff in that package size.

Graham

Indeed, but the BD135 and BD136 aren't very impressive when used as switches above 200 to 400mA. That's because they're total wimps for beta above 400 to 500mA, under 75 typical, and only 25 worst case, even for the high-beta version. And their collector-saturation voltage rapidly rises above 500mA, where it's already up to 500mV. Diederick says he wants to switch 800mA, where the worst-case limit is 810mV at 25C, rising to perhaps 1000mV at higher temps. And that's with a very painful rather-high 80mA drive!

By comparison a part like the Zetex ZTX849, for example, will run nice and cool, thanks to its beta of 100 min, 200 typical and its low 50mV saturation voltage at 1000mA, which is with, note!, only 20mA base drive! An amazing part like that can give a small MOSFET a real run for its money! In fact, Zetex' entire Super E-line TO-92 series is amazing.

BTW, the FZT849 and ZXT849 are pretty cool parts as well, more SMTs helping to give the old TO126 case a permanent heave-ho. The ZTX649 is a little less expensive.

I have had more bond failures with the TO126 case than with all other cases combined. The combination of stiff lead frame and minimal epoxy to contain them is very poor, in my opinion.

Hello Win,

Ouch. This application really calls for FETs if he has enough gate drive voltage.

Hi all,

I've bought the bc337 NPN (max 800mA) and bc327 PNP (also max 800mA), which work great for now! I'll keep you informed when I change transistors.

Greetings