True. Especially if you want to put more than 1 cap on the input and output= side for performance/secure reason. There must be some good chip and design which has the cost balanced. Soluti= ons from National Semi and Linear are not cheap. Funny N. Au Group Electronics, New Bedford, MA, http://www.AuElectronics.com ----- Original Message ---- From: Vasile Surducan To: Microcontroller discussion list - Public. Sent: Wednesday, June 25, 2008 2:40:15 PM Subject: Re: [EE] Switch voltage Regulator - What chip to use? On 6/25/08, Rolf wrote: > Rolf wrote: > > Bob wrote: > > > >> Hi, > >> > >> > >> > >> Have been searching for a suitable switching regulator IC and I am tot= ally > >> confused by the 1,000's of different types available!!! > >> > >> > >> > >> Can anyone suggest a 'popular' easily available IC? Or a simple circui= t? > >> > >> > >> > >> 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,C10= 32 > > > > Then type in your specifications (I get URL: > > > > http://www.linear.com/pc/categoryProducts.jsp?vin_min=3D20&vin_max=3D50= &qpsActive=3Dtrue&action=3DINITIAL&vout=3D5&filterOnInit=3Dtrue&iout=3D0.5&= navId=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. The funniest thing is when you buy the capacitor with $8 and the regulator itself is $1.4... aka Digikey. -- = 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