three terminal volt regulator

Started by George Herold July 12, 2018
Hi all, Simple question.  Some 1/2 amp LM7805 is obselete (TO-220 pac) 

I need a replacement.  So either a 1 amp 7805
http://www.onsemi.com/pub/Collateral/MC7800-D.PDF

or a LM340
http://www.ti.com/lit/ds/symlink/lm340.pdf

Is there any (practical) difference between the two?  (besides the price.) 

George H.

Generally, 5 volts is 5 volts. The price shouldn't be a major concern unless you are
building a million units. In, ground and out.

At ½ amp you could probably shunt regulate it, a Zener would only dissipate
2.5 watts at no load. Not efficient but probably the cheapest option. 

Between the LM340XX-5 and the 7805, I'd get whichever is cheaper.
In article <6fc3dbef-b41a-4a8f-a3eb-5033c5742824@googlegroups.com>, 
gherold@teachspin.com says...
> Hi all, Simple question. Some 1/2 amp LM7805 is obselete (TO-220 pac) > > I need a replacement. So either a 1 amp 7805 > http://www.onsemi.com/pub/Collateral/MC7800-D.PDF > > or a LM340 > http://www.ti.com/lit/ds/symlink/lm340.pdf > > Is there any (practical) difference between the two? (besides the price.) > >
All of the regulators of that type are the same as far external circuits go. As long as the voltage and current ratings are the same or greater, just go with whatever you want. Just do not interchange the positive ones and negative ones.
In article <MPG.35b15dce3aab8110989804@news.east.earthlink.net>, 
rmowery28146@earthlink.net says...
> > All of the regulators of that type are the same as far external circuits > go. As long as the voltage and current ratings are the same or greater, > just go with whatever you want. > > >
That should have been the voltage the same and the current same or greater.
On Thursday, July 12, 2018 at 1:01:55 PM UTC-4, jurb...@gmail.com wrote:
> Generally, 5 volts is 5 volts. The price shouldn't be a major concern unless you
are building a million units. In, ground and out.
> > At &frac12; amp you could probably shunt regulate it, a Zener would only dissipate
2.5 watts at no load. Not efficient but probably the cheapest option.
> > Between the LM340XX-5 and the 7805, I'd get whichever is cheaper.
Thanks, I ordered the cheaper 7805... just wondering. George H.
On 2018-07-12, George Herold <gherold@teachspin.com> wrote:
> Hi all, Simple question. Some 1/2 amp LM7805 is obselete (TO-220 pac)
??? http://www.ti.com/product/lm78m/description -- &#1578;
George Herold wrote:
> > > Hi all, Simple question. >
** So they all say ....
> Some 1/2 amp LM7805 is obselete (TO-220 pac) >
** TO220 pac 7805s are rated at 1.5 amps, long as chip dissipation is not exceeded. IIRC, obsolete TO202 pac LM341s were 0.5 amp.
> I need a replacement. So either a 1 amp 7805 > http://www.onsemi.com/pub/Collateral/MC7800-D.PDF > > or a LM340 > http://www.ti.com/lit/ds/symlink/lm340.pdf > > Is there any (practical) difference between the two? (besides the price.) >
** IME, no. Some devices have both numbers printed on them. FYI: had to replace a couple of 7815s the other day in a dBx dual 31 band graphic. The regs were full pac versions with NEC brand name. After warming up a little, both examples shut down completely. ... Phil
On 07/12/18 12:34, George Herold wrote:
> Hi all, Simple question. Some 1/2 amp LM7805 is obselete (TO-220 pac) > > I need a replacement. So either a 1 amp 7805 > http://www.onsemi.com/pub/Collateral/MC7800-D.PDF > > or a LM340 > http://www.ti.com/lit/ds/symlink/lm340.pdf > > Is there any (practical) difference between the two? (besides the price.) > > George H. >
As long as you're using an electrolytic cap on the output, the two ought to be equivalent, but they might behave differently with big ceramic or alpo caps, whose ESR is very low. For instance, the ON Semi TLV431 is far more prone to oscillate than the TI or Diodes versions. National used to label its TO220 regulators with both LM7805 and LM340-5 on the same part--I still have some like that. With old parts like that, it's hard to know if what TI is selling these days is the old TI part or the old National part or what. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
On Thursday, July 12, 2018 at 3:31:21 PM UTC-4, Jasen Betts wrote:
> On 2018-07-12, George Herold <gherold@teachspin.com> wrote: > > Hi all, Simple question. Some 1/2 amp LM7805 is obselete (TO-220 pac) > > ??? > > http://www.ti.com/product/lm78m/description > > -- > &#1578;
Huh, Thanks... I'll order some of those then. (The Onsemi parts are going away.) George H.
On Thu, 12 Jul 2018 13:45:59 -0400, Ralph Mowery
<rmowery28146@earthlink.net> wrote:

>In article <6fc3dbef-b41a-4a8f-a3eb-5033c5742824@googlegroups.com>, >gherold@teachspin.com says... >> Hi all, Simple question. Some 1/2 amp LM7805 is obselete (TO-220 pac) >> >> I need a replacement. So either a 1 amp 7805 >> http://www.onsemi.com/pub/Collateral/MC7800-D.PDF >> >> or a LM340 >> http://www.ti.com/lit/ds/symlink/lm340.pdf >> >> Is there any (practical) difference between the two? (besides the price.) >> >> > >All of the regulators of that type are the same as far external circuits >go. As long as the voltage and current ratings are the same or greater, >just go with whatever you want.
As long as it doesn't oscillate. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com