On 6/1/07, enkitec@gmail.com wrote: > > Hi, > > I need to power a uP circuit with 3.3V @ 6mA from a 4700uF capacitor > charged to 12V. The circuit has to run until the capacitor discharges. > Have tried the Roman Black's SMPS circuits, but could'n go over 50% > efficiency at this 6mA current output. Even the Zener diode current is > excessive... > > Any ideas? Low cost and part number is a constrain. 1 resistor and one zenner (maybe a TL431) if you can loose around 60mW. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist