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From: Tong Narak
Subject: Re: LM317 or 7808 is better performance for 9V output ?
Date: Wed, 04 Dec 2002 22:36:35 +0700
Organization: C.S. Communications Co. Ltd.
NNTP-Posting-Date: Wed, 4 Dec 2002 15:36:42 +0000 (UTC)
X-Mailer: Mozilla 4.8 [en] (Windows NT 5.0; U)
Um... I have ton of 7808 and 7805 chips.
And I just want to know about performance and efficiency ?
Someone recommend LM317 as adjustable regulator always.
I think it is just a 1.25v regulator and adjust output by shift
the ground level. I think it is 7801.
Nobody tell us to use 7805.. The head room voltage just 2v.
7805 can adjustable output as LM317. it can work as current
regulator the same way as LM317.
Which one is better ?
I think 78xx is better because head room drop as low as 2v.
And the pinout is more make sense.
> On Wed, 04 Dec 2002 14:16:26 +0700, Tong Narak
> >Hi all,
> >A. LM317 require 5V head room.
> >B. 78XX require 2V head room ( Is these correct ? ).
> >I would like to set the output to 9V. Load ~300mA.
> >(1) Which one is better proformance and efficiency ?
> >(2) 7805 and 7808 are same efficiency when adjustable to 9V ?
> >Thanks for advance.
> Why not just use a 7809?
> Jenal Communications
> Manufacturers and Suppliers of HF Selcall
> P O Box 1108, Morley, WA, 6943
> Tel: +61 8 9370 5533 Fax +61 8 9370 5106
> Web Site: http://www.jenal.com
> e-mail: http://www.jenal.com/contact.php
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