Generally, most phone chargers will need 5.5V to successfully and completely charge its battery, expecting the battery is either a 3 cell Ni or 1 cell Li. I agree that ripple is a greater concern with ADC measurements and other components in the design, and less of a concern for most micros as long as the supply voltage does not drop below or rise above specs. ----- Original Message ----- From: "Olin Lathrop" To: "Microcontroller discussion list - Public." Sent: Thursday, May 12, 2005 7:15 AM Subject: Re: [EE] Will phone charger work as a 5v DC power supply? > Lindy Mayfield wrote: >> When does ripple cause problems? Will a rippled (rippling?) input >> cause a problem with PICS? > > Ripple means the supply bounces around hopefully between two known limits. > First and foremost those limits must not exceed the PICs Vdd limits for > its > operating mode. As long at that is true, the PIC should continue to work. > However, the external circuit may not be so happy with that. If you're > trying to make analog measurement, supply ripple can be a problem. The > same > is true if the PIC is trying to produce an output voltage for uses not > relative to the supply voltage. For example, if the PIC is producing PWM > that will be low pass filtered and driven into a speaker with respect to > ground, then you will hear the ripple to the extent it is in the range of > frequencies passed by the filter and the speaker. > > High frequency ripple is also bad due to its dV/dt, but that is usually > not > an issue for 120Hz power line ripple. > > > ***************************************************************** > Embed Inc, embedded system specialists in Littleton Massachusetts > (978) 742-9014, http://www.embedinc.com > -- > 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