I've used the TC55 series regulators to keep down the PSU power consumption, with consistent success. These are now obsolescent, the TC56 is the updated version. Quiescent power is 11uA, or 100nA during power down.
For desperately low consumption. add a big low-leakage capacitor at the output, then have the MSP430 wake up and enable the regulator for a few milliseconds from time to time. Datasheet is at http://ww1.microchip.com/dhttp://ww1.microchip.com/downloads/en/DeviceDoc/21436b.pdfownloads/en/DeviceDoc/21436b.pdf -- Rick Jenkins <r...@hartmantech.com> Hartman Technica http://www.hartmantech.com Phone +1 (403) 230-1987 voice & fax 221 35 Avenue. N.E., Calgary, Alberta, Canada T2E 2K5
