OK for the switcher I don't mind changing. But what are the available packages and external components in order to use the switching regulators ? I would like them to be drop-in replacements ... regards, TH ----- Original Message ----- From: "David VanHorn" To: Sent: Tuesday, November 13, 2001 1:19 PM Subject: Re: [EE]: 7805 pin compatible switching regulator ? > At 04:10 PM 11/13/01 -0200, Marcelo Yamamoto wrote: > >If I remember correctly 78xx series have a thermal shutdown. They are rated > >for 1.5A. At this current and 24V supplying it, you will have: > >Power= 1.5x(24-5)= 28.5W > >Ensure you have a BIG heatsink or proper ventilation. > >Use a linear series regulator to drop the voltage to something around 8V and > >put the regulator after it. It will be more reliable than a simple > >transistor and a zener in a series regulator. > > No matter how you slice it, it's still bologna. > > If the output is 1A, then he has to get rid of 19W of heat. > Using a pre-reg just moves the heat to a different place. > This is why we use switchers. The waste will be more in the range of 0.5W. > > Input power will drop from 24W to something like 5.5W. > -- > Dave's Engineering Page: http://www.dvanhorn.org > > Got a need to read Bar codes? http://www.barcodechip.com > Bi-directional read of UPC-A, UPC-E, EAN-8, EAN-13, JAN, and Bookland, with > two or five digit supplemental codes, in an 8 pin chip, with NO external parts. > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads