On 6/11/08, Alan B. Pearce wrote: > >Use the AD reference at 4V or so. Where do you get inexpensive > >4V or so reference? > >TL431 or LM431 > > Anyone looking for low noise accurate references may like to look at the new > Analog Devices range. Look at the ADR44x range, each voltage output comes in > 2 grades of tolerance, and includes 2.048 and 4.096V references. That is a totally different grade of component than the TL431. I am using ADR03 and tried ADR421 as well because of their good temperature drift performance (3ppm worst case). They have much better speciifcation than the TL431 and are much more expensive as well. But TL431 is more than a reference. You can refer to the following written by the famous R. B. Ridley (ok, he is famous only in the field of power electronics). http://switchingpowermagazine.com/downloads/15%20Designing%20with%20the%20TL431.pdf Xiaofan Xiaofan -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist