PIC VPP limiter schematic
Newer PIC18s, such as my current favorite – PIC18F26K20, don’t like to be programmed with 12V. The datasheet maximum is 9V. Older Microchip programmers/debuggers, such as PicKit and ICD 2, do not support variable programming voltage. When you start a MPLAB project consisting of K-series PIC18 and ICD 2 debugger, you will get a warning and suggested VPP limiting circuit schematic. In this article I’m describing this very circuit, so you can build it beforehand.