I'm making some replacement boards for a system I designed a while ago. 1980, actually. The power regulator board used a couple of LM376's, a nice little DIP8 voltage regulator that drives an off-board heatsunk PNP pass transistor. LM376 seems to be unavailable. But I can't find a substitute, namely a linear voltage regulator controller with foldback capability and external PNP pass transistor. Well, you could hack it with a 723, an even more ancient part. Strange that there's no equivalent, at least none I can find. Anybody know of one? I could make it out of opamps and stuff, I guess, or use an LM1117 in PNP-boost mode, with extra junk for the current liniting. The 376 was so elegant. John
regulator thingie
Started by ●June 21, 2011
Reply by ●June 21, 20112011-06-21
On Tuesday, June 21, 2011 10:48:26 AM UTC-7, John Larkin wrote:> I'm making some replacement boards [for a design using] > LM376's, a nice little DIP8 voltage regulator that drives an off-board > heatsunk PNP pass transistor.LP2951 is still available, might be suitable... somewhat. The offboard pass transistor might be better run by a four-terminal regulator rather than a three-terminal type; the addition of a current sense resistor is simplified somewhat if you do it that way.
Reply by ●June 21, 20112011-06-21
On 21 Jun., 19:48, John Larkin <jjlar...@highNOTlandTHIStechnologyPART.com> wrote:> I'm making some replacement boards for a system I designed a while > ago. 1980, actually. The power regulator board used a couple of > LM376's, a nice little DIP8 voltage regulator that drives an off-board > heatsunk PNP pass transistor. > > LM376 seems to be unavailable. But I can't find a substitute, namely a > linear voltage regulator controller with foldback capability and > external PNP pass transistor. Well, you could hack it with a 723, an > even more ancient part. > > Strange that there's no equivalent, at least none I can find. Anybody > know of one? I could make it out of opamps and stuff, I guess, or use > an LM1117 in PNP-boost mode, with extra junk for the current liniting. > > The 376 was so elegant. > > Johnone of the first hits on google is UC2836D digikey have some, though not cheap at ~10$ -Lasse
Reply by ●June 21, 20112011-06-21
On Tue, 21 Jun 2011 14:35:11 -0700 (PDT), "langwadt@fonz.dk" <langwadt@fonz.dk> wrote:>On 21 Jun., 19:48, John Larkin ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> I'm making some replacement boards for a system I designed a while >> ago. 1980, actually. The power regulator board used a couple of >> LM376's, a nice little DIP8 voltage regulator that drives an off-board >> heatsunk PNP pass transistor. >> >> LM376 seems to be unavailable. But I can't find a substitute, namely a >> linear voltage regulator controller with foldback capability and >> external PNP pass transistor. Well, you could hack it with a 723, an >> even more ancient part. >> >> Strange that there's no equivalent, at least none I can find. Anybody >> know of one? I could make it out of opamps and stuff, I guess, or use >> an LM1117 in PNP-boost mode, with extra junk for the current liniting. >> >> The 376 was so elegant. >> >> John > >one of the first hits on google is UC2836D >digikey have some, though not cheap at ~10$ > >-LasseInteresting part. Unitrode datasheet from 1994. Yes, it is a bit expensive. Looks like the best bet is to use an LM723, which is a, what, 40 year old chip? Lots of people still make the 723, and all the datasheets seem to be cribbed from the Fairchild original. And none discusses compensation in any detail. It's impressively under-specified. I suppose I'll hang a big cap on the comp pin, maybe a series R for luck, or else go into the schematic and analyze the beast. John
Reply by ●June 21, 20112011-06-21
On 22/06/2011 3:48 AM, John Larkin wrote:> > > I'm making some replacement boards for a system I designed a while > ago. 1980, actually. The power regulator board used a couple of > LM376's, a nice little DIP8 voltage regulator that drives an off-board > heatsunk PNP pass transistor. > > LM376 seems to be unavailable. But I can't find a substitute, namely a > linear voltage regulator controller with foldback capability and > external PNP pass transistor. Well, you could hack it with a 723, an > even more ancient part. > > Strange that there's no equivalent, at least none I can find. Anybody > know of one? I could make it out of opamps and stuff, I guess, or use > an LM1117 in PNP-boost mode, with extra junk for the current liniting. > > The 376 was so elegant. > > John >How about this supplier: http://www.mikes-hobby-shop.com/servlet/the-1670/LM-376-OP-AMP/Detail $1.75 in single quantities. Don't know how many they have but worth a try.
Reply by ●June 21, 20112011-06-21
On Jun 21, 1:48=A0pm, John Larkin <jjlar...@highNOTlandTHIStechnologyPART.com> wrote:> I'm making some replacement boards for a system I designed a while > ago. 1980, actually. The power regulator board used a couple of > LM376's, a nice little DIP8 voltage regulator that drives an off-board > heatsunk PNP pass transistor. > > LM376 seems to be unavailable. But I can't find a substitute, namely a > linear voltage regulator controller with foldback capability and > external PNP pass transistor. Well, you could hack it with a 723, an > even more ancient part. > > Strange that there's no equivalent, at least none I can find. Anybody > know of one? I could make it out of opamps and stuff, I guess, or use > an LM1117 in PNP-boost mode, with extra junk for the current liniting. > > The 376 was so elegant. > > JohnIt crosses to NTE1930 and ECG1930 exact replacements and you can still find those in stock although obsolete too.
Reply by ●June 22, 20112011-06-22
It looks like the current limit on the UC3836 is permanently wired for 2.5A (maybe you could parallel a resistor to get it to go higher, but not lower). uA723/LM723 is OK for higher voltages (9.5V minimum input) and LP2951 for low voltages (2V to 30V input range). None of these is a straight substitute for the LM376, though.
Reply by ●June 22, 20112011-06-22
On Tue, 21 Jun 2011 10:48:26 -0700 John Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in Message id: <ful107hc4if8pdn1eukhnbavctl33j7o4j@4ax.com>:> > >I'm making some replacement boards for a system I designed a while >ago. 1980, actually. The power regulator board used a couple of >LM376's, a nice little DIP8 voltage regulator that drives an off-board >heatsunk PNP pass transistor. > >LM376 seems to be unavailable. But I can't find a substitute, namely a >linear voltage regulator controller with foldback capability and >external PNP pass transistor. Well, you could hack it with a 723, an >even more ancient part. > >Strange that there's no equivalent, at least none I can find. Anybody >know of one? I could make it out of opamps and stuff, I guess, or use >an LM1117 in PNP-boost mode, with extra junk for the current liniting. > >The 376 was so elegant.According to http://www.national.com/kbase/category/Power.html#114 "LM376 was an LM305 in a plastic DIP package" Which can still be found, but not cheap by any means. http://www.findchips.com/avail?part=LM305 http://www.oemstrade.com/search/LM305/
Reply by ●June 22, 20112011-06-22
John Larkin wrote:> > > I'm making some replacement boards for a system I designed a while > ago. 1980, actually. The power regulator board used a couple of > LM376's, a nice little DIP8 voltage regulator that drives an off-board > heatsunk PNP pass transistor. > > LM376 seems to be unavailable. But I can't find a substitute, namely a > linear voltage regulator controller with foldback capability and > external PNP pass transistor. Well, you could hack it with a 723, an > even more ancient part. > > Strange that there's no equivalent, at least none I can find. Anybody > know of one? I could make it out of opamps and stuff, I guess, or use > an LM1117 in PNP-boost mode, with extra junk for the current liniting. > > The 376 was so elegant. > > John >I used to like the LM611/613/614 for that job. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics Electro-optics Photonics Analog Electronics 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 email: hobbs (atsign) electrooptical (period) net http://electrooptical.net
Reply by ●June 22, 20112011-06-22
On Wed, 22 Jun 2011 06:32:16 -0400, JW <none@dev.null> wrote:>On Tue, 21 Jun 2011 10:48:26 -0700 John Larkin ><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in Message id: ><ful107hc4if8pdn1eukhnbavctl33j7o4j@4ax.com>: > >> >> >>I'm making some replacement boards for a system I designed a while >>ago. 1980, actually. The power regulator board used a couple of >>LM376's, a nice little DIP8 voltage regulator that drives an off-board >>heatsunk PNP pass transistor. >> >>LM376 seems to be unavailable. But I can't find a substitute, namely a >>linear voltage regulator controller with foldback capability and >>external PNP pass transistor. Well, you could hack it with a 723, an >>even more ancient part. >> >>Strange that there's no equivalent, at least none I can find. Anybody >>know of one? I could make it out of opamps and stuff, I guess, or use >>an LM1117 in PNP-boost mode, with extra junk for the current liniting. >> >>The 376 was so elegant. > >According to http://www.national.com/kbase/category/Power.html#114 >"LM376 was an LM305 in a plastic DIP package" > >Which can still be found, but not cheap by any means. >http://www.findchips.com/avail?part=LM305 >http://www.oemstrade.com/search/LM305/I don't think any of them are still in production, and old parts from brokers are risky. Looks like a ua723 will do what I want, but it has a lot of constraints. I was just sort of surprised that nothing like the 376 is still made. What do people do when they need a big honking linear power supply? Make the controller from a reference and a couple of opamps and a transistor or two, I guess... a lot of parts to replace one DIP8. Seems strange that the best, basically only, linear regulator controller left, the 723, is about 40 years old. John
