Andy A series resistor will get the majority of the dissipation away from the IC. You can let the regulator drop only a few volts when you are at full design current. At low or no current the regulator will take most of the dissipation and voltage but it will be less critical. You nominated SMT but the resistors may not have to be. 4 x Philips SFR16 series resistors will handle max required dissipation (and will mount in about 6mm x 3mm space each if necessary) and there are of course lots of metal film resistors which will handle this power in a single unit. regards Russell McMahon. -----Original Message----- From: Andy Kunz To: PICLIST@MITVMA.MIT.EDU Date: Saturday, May 15, 1999 6:31 AM Subject: voltage regulator question >Anybody know of a SMT regulator which can handle 45V input, 5V/50mA output? > 40V * 50mA = 2W - an awful lot for a tiny PCB to handle. > >I'm finding very few options in the datasheets. > >PCB size is a premium. Reliability is SUPER important, component >cost/complexity is secondary. > >Ideas? > >Thanks! > >Andy > >================================================================== > Montana Design Tech Support - http://www.montanadesign.com >================================================================== >