tonymillar
New Member
Hi. I have a project in development that consists of an 08M2 & an 18M2. The 08M2 manages a DS3231 RTC & the 18 has a number of analogue & digital inputs. I have tried researching the PIC datasheets, but the quoted electrical characteristics do not include minimum input current requirements. e.g. for the voltage divider to measure the battery voltage, I am currently using a 3k and 500 ohm resistor ladder. Theoretically that gives me 1.714V at the tap, with a 12V supply. The current in the ladder is (theoretically) 3.42mA. I would like to reduce the current in this (& all other analogue inputs. If I scale the ladder by a factor of 100, i.e 300K & 50K, the voltage drops 0.93V. This tells me the input is drawing more current than the ladder can supply. Does anyone know what the minimum current is that is required by an analogue input on an 18M2. Thanks