That's a chip operating at 52K Hz, there are also some 150K Hz buck converter from National semi. The higher frequency, the smaller the overall power system would be, also the cheaper on L and C components. Funny N. Au Group Electronics, New Bedford, MA, http://www.AuElectronics.com ----- Original Message ---- From: Bob To: piclist@mit.edu Sent: Wednesday, June 25, 2008 6:41:57 AM Subject: RE: [EE] Switch voltage Regulator - What chip to use? Hi, Many thanks for all the replies. I have looked at the links and found (tripped over) a suitable IC. It is the LM2574HV which will handle an input voltage of 63v and give 5v at 500mA. Have just ordered some so thanks again. Bob -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of Bob Sent: 25 June 2008 9:58 AM To: piclist@mit.edu Subject: [EE] Switch voltage Regulator - What chip to use? Hi, Have been searching for a suitable switching regulator IC and I am totally confused by the 1,000's of different types available!!! Can anyone suggest a 'popular' easily available IC? Or a simple circuit? It needs to handle an input voltage between 20 and 50 volts, supply a current of between 30mA and 500mA with an output voltage of 5 volts. Thanks, Bob -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist No virus found in this incoming message. Checked by AVG. Version: 8.0.101 / Virus Database: 270.4.1/1517 - Release Date: 24/06/2008 8:41 pm -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist