I have used the 16HV540 in a design too... I used a 9V battery as:- a) there was a case that hard a compartment for them b) the higher voltage gave a better volume from a Piezo alarm With the part in sleep mode - and the circuit designed so that the PIC I/O = pins supplied power to the peripherals (meant everything could be turned = off) I was able to have a sleep current of 5uA. I don't believe there are any other PICs with the regulators onchip ... it = seems a shame as the HV540 is basically a 16C54 so it has very few = hardware peripherals. >>> andscott@LOGANTELE.COM 05/13/02 12:38AM >>> For the PIC I used a 16HV540 which has built in voltage regulators. Do these regulators have the same losses as a 7805? My guess is that they don't since my current consumption was low and I calculated(?) a 5 year battery life. The 16HV540 seems to be a unique chip. With the built in regulators there are also several features to lower voltages during sleep, power the I/O ports, etc. Are there any other PICs or other MCUs that will take the high (9V+) supply voltages? -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics