I found out the hard way that forward biasing either of the protection diodes on any analog input pin-- even with a small amount of current-- can cause ADC conversion errors on the other analog input pins. The best policy, I decided, was to ensure ALL pins on the device are kept between Vss and Vdd at ALL times, no matter what.I used a PIC in an application which fed a negative voltage to a pin with a resistor to limit the current well below the limit. It didn't damage the PIC but the internal oscillator was very messed up while that negative voltage was present. Major redesign required.
All of that information is in the data sheet, in the Electrical Characteristics section. Read the data sheet.How can I find current limits for the 18f8527...
Be aware of the difference between CMOS and TTL voltage differences. The chips I use default to TTL, which is not usually a problem, even when using level shifters to 3.3 V.thanks guys, as every some insightful information.
How can I find current limits for the 18f8527, the design I am looking at has no more than some voltage dividers going to the PIC which will be interpreted as a logic low or high, In the example below 6V will be at RF1 but I have seen instances of 8.5V been present on other pins, hence the topic
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Good advice for EVERY component you use, especially ICs-- not just PICs. Doing so will save you a lot of grief and help you avoid costly-- or even catastrophic-- mistakes."Study" the datasheet.
by Duane Benson
by Jake Hertz
by Jake Hertz
by Aaron Carman