It is true, more money on the Caps and Inductors are the cost for a higher = efficiency. = Compare with LDOs, It is a $10 on SMPS Vs. $2-3 LDO. For high voltage system, that's the cost you must pay. Funny N. Au Group Electronics, New Bedford, MA, http://www.AuElectronics.com ----- Original Message ---- From: Rolf To: Microcontroller discussion list - Public. Sent: Wednesday, June 25, 2008 11:26:27 AM Subject: Re: [EE] Switch voltage Regulator - What chip to use? Rolf wrote: > Bob wrote: > = >> Hi, >> >> = >> >> Have been searching for a suitable switching regulator IC and I am total= ly >> 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 >> >> = >> = > Hi Bob. > > Don't know about popularity, but I like Linear stuff (I'm a hobbyist). I = > have even made a piece that uses a Linear switcher (the LT1111 - which = > has 30V max input). The thing I like about Linear is it's good website: > > It is easy to find: > http://www.linear.com/pc/viewCategory.jsp?navId=3DH0,C1,C1003,C1042,C1032 > > Then type in your specifications (I get URL: > > http://www.linear.com/pc/categoryProducts.jsp?vin_min=3D20&vin_max=3D50&q= psActive=3Dtrue&action=3DINITIAL&vout=3D5&filterOnInit=3Dtrue&iout=3D0.5&na= vId=3DH0%2CC1%2CC1003%2CC1042&y=3D5&x=3D25 > > ) which has probably wrapped horribly.... > > > And the most promising one looks like: LT1956-5 which will give just = > less than 90% efficiency at 5V with a 500kHz freq and 10uH inductor.... = > although at the 30mA side the efficiency is less..... from 250mA through = > 1A it looks great. > > Rolf > > = In reply to myself .... I love it when you read things like this in a = datasheet.... (from Linear's LT1956-5...) TPS capacitors are specially constructed and tested for low ESR, so they give the lowest ESR for a given volume. The value in microfarads is not particularly criti- cal, and values from 22=B5F to greater than 500=B5F work well, but you cannot cheat mother nature on ESR. If you find a tiny 22=B5F solid tantalum capacitor, it will have high ESR, and output ripple voltage will be terrible. Rolf -- = 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