At 04:19 PM 11/9/99 -0500, Dave wrote: > > There is apparently never a reason to use higher than 100 uF or lower than > > 0.1 uF on the regulator output. And with lower values, you don't need a > > discharge resistor or diode to protect the regulator. > >Important point, the 100 or whatever is IN ADDITION to the 0.1uF. >The larger caps don't work so well at 1-2 MHz, which is what the 0.1 is >there for. Again, I'm not an EE. However, I'm not sure I agree with this 'conventional wisdom'. The point of concern is the impedance of the capacitor at the frequency of interest. Although smaller capacitors may have less lead inductance, the higher capacitance of the larger ones may result in a lower impedance at that frequency, giving better performance. Any analysis I've seen has always indicated that higher capacitance is better, even at reasonably high frequencies (e.g., 20 MHz). E.g., a 10 uF tantalum is superior to a 0.1 uF tantalum or ceramic. Perhaps Paul or Michael have something to contribute on this issue. ================================================================ Robert A. LaBudde, PhD, PAS, Dpl. ACAFS e-mail: ral@lcfltd.com Least Cost Formulations, Ltd. URL: http://lcfltd.com/ 824 Timberlake Drive Tel: 757-467-0954 Virginia Beach, VA 23464-3239 Fax: 757-467-2947 "Vere scire est per causae scire" ================================================================