Thanks Bob, But I forgot to say, that the system will use 2 button cell (lithium) batteries in parallel, so Vdd is 6volt, and will use a 4mhz Xtal, cause it has to download data every 1 month. Another thing, is that I have never been able to get a lower consumption that 0.08 ma @5v, in sleep mode !!! So, what can I do ? -----Mensaje original----- De: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]En nombre de Bob Ammerman Enviado el: Jueves, 20 de Junio de 2002 23:56 Para: PICLIST@MITVMA.MIT.EDU Asunto: Re: [PIC]: Turning on a PIC micro every 5 minutes..... If you PIC will be on and working 20 seconds out of every 300 seconds then SLEEP should be a good choice for you. Here is why: Assumptions (adjust to match your application): Active power consumption = 3ma (1 ma for PIC at 3.3V + 2ma for whatever else you are doing) Sleep power consumption = 0.0022ma (Ipd from data sheet) + 0.010ma (assumption for using a 32KHz XTAL on timer 1 for wakeup) power consumed per 300 seconds while active = 20 seconds * 3 ma = 60 ma seconds power consumed per 300 seconds while sleeping = 280 seconds * 0.0122 ma = 3.4 ma seconds Obviously the power consumed during the non-sleep interval greatly exceeds the sleep time. About 95% of your available battery capacity is used doing useful work. Bob Ammerman RAm Systems ----- Original Message ----- From: "Gabriel Caffese" To: Sent: Thursday, June 20, 2002 10:54 PM Subject: [PIC]: Turning on a PIC micro every 5 minutes..... Hello everyone, I have a project where I have to take GREAT care of battery life. It4s a portable system with a 16F627, that has to make some measurements every 300 seconds, and stay on for 20 seconds. Once the system is turned on, it will NEVER be turned off. So, system4s life depends on batteries life. When batteries die, the whole system is disposed. For the batteries I have to use, putting the 16F627 in sleep mode wouldn4t be a solution, cause I would be far away from where I should (in terms of battery life). Now, the question: I thought of using a DS1337 RTC, wich has an alarm output that could be configured to power the PIC every 60 seconds. I4ve also thought of use a 4060 counter, and others in cascade, but....... Would there be a better solution (cheaper, easier) for powering the 16F627 ? Thanks in advance, Gabriel.- -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu