Npn-Pnp combo IC - Page 1
Forum section: electronics / beginners

author: sparksflying
author_rank: Contributor
timestamp: June 06, 2014, 04:36:35 am
content: Hello,I am making something that uses PNP-NPN transistors to switch a higher voltage than the logic control voltage.Like this:http://jeelabs.org/wp-content/uploads/2012/11/npn-pnp.pngI'll be putting 30 or so of these on my board. With 4 discreet componets per output, that's a lot of time to place components. I'm sure there would be an IC that incorporates all of this with multiple channels per chip.What would this type of chip be called?

author: mariush
author_rank: Super Contributor
timestamp: June 06, 2014, 04:40:53 am
content: See these pages.. check pnp+npn or other categories :http://uk.farnell.com/transistors-bipolar-bjt-arrayshttp://www.digikey.com/product-search/en/discrete-semiconductor-products/transistors-bjt-arrays/1376378http://www.digikey.com/product-search/en/discrete-semiconductor-products/transistors-bjt-arrays-pre-biased/1377267get the chip name, then look up on findchips.com or whatever store is more convenient for you.

author: DJohn
author_rank: Regular Contributor
timestamp: June 06, 2014, 07:44:16 am
content: That's a 'source driver' or 'high-side driver'. Some just provide your circuit (or a slightly more elaborate version) repeated a few times. You can also get ones with internal latches and shift registers, which is useful if you have a lot of channels and not enough I/O on your processor.

author: fcb
author_rank: Super Contributor
timestamp: June 06, 2014, 08:30:01 am
content: Possible options.1. Could replace the NPN with a 2N7002 and save the base resistor (depending on your high side supply voltage)2. Replace the NPN with a digital transistor (same results as above) - e.g. MMUN22113. Replace both the NPN and PNP with digital transistors (how much power is your load taking??) - e.g. MMUN2211 & MMUN21114. Use a SOT23-6 packaged part like the BC847BPN (although this is really only good for machine placement)5. Use something like a ULN2803A to replace the 8x NPN's and base resistors.

author: nuno
author_rank: Frequent Contributor
timestamp: June 06, 2014, 11:01:38 am
content: Or a complementary pair of FET in 6 pin smd, ditching the resistors:http://pt.mouser.com/Search/ProductDetail.aspx?R=FDC6327Cvirtualkey51210000virtualkey512-FDC6327CBut there's probably some other kind of chip for that, what you want is a "non-inverting driver", depending on the load type and required current you may find some "buffers" that can handle it, and buffers may come in sets of 8 in a chip.

author: sparksflying
author_rank: Contributor
timestamp: June 07, 2014, 01:24:59 pm
content: Thanks guys, I'll look through my options

author: sparksflying
author_rank: Contributor
timestamp: June 17, 2014, 02:27:03 am
content: End up going with the PUMD15, Digital Transistor, NPN, PNP 100mA 50V 4.7k?, Ratio Of 1, 6-Pin UMThttp://au.rs-online.com/web/p/digital-transistors/5183728/?searchTerm=5183728&relevancy-data=636F3D3126696E3D4931384E525353746F636B4E756D6265724D504E266C753D656E266D6D3D6D61746368616C6C26706D3D5E5C647B367D247C5E5C647B377D247C5E5C647B31307D2426706F3D313426736E3D592673743D52535F53544F434B5F4E554D4245522677633D4E4F4E45267573743D3531383337323826#Thanks

author: Swake
author_rank: Frequent Contributor
timestamp: June 17, 2014, 12:57:12 pm
content: Have a look at the Darlington Driver 8-Channel ULN2803.I quote from Sparkfun and the PDF:Description: 8 Darlington Arrays in 18-Pin DIP Package part # ULN2803A. Perfect for running relays and high-power devices up to 500mA and up to 50V.the ULN2803Ahas a 2.7k? input resistor for 5V TTL and CMOSCosts is about 2$/piece

author: Swake
author_rank: Frequent Contributor
timestamp: June 17, 2014, 12:59:11 pm
content: And several chips exists in this family with slight different specs.

author: AnalogKid
author_rank: Newbie
timestamp: June 17, 2014, 03:12:57 pm
content: If you can find them, the UDN2981 and UDN2982 sound like a fit. TI discontinued them, but they probably are on ebay. Other than that, you can do arrays of 3904s, 3906s, and resistors to reduce the handling over discretes.ak

author: Richard Crowley
author_rank: Super Contributor
timestamp: June 17, 2014, 03:44:58 pm
content: Of course, at least for completeness (although never disclosed by the OP) the preferable way to do this is to switch the LOW end which is much simpler and capable of handling most any supply voltage and current (with the appropriate transistor, of course). But there are some cases where you must switch the high-side, and perhaps this was one of them. But you can see that it significantly complicates the situation.