EMBEDDED SYSTEMS & MICROCONTROLLERS · PAGE 63
ESD and EMC Protection
Surviving sparks and interference.
A static spark from a finger can destroy an exposed pin. Add series resistors, protection diodes or special clamp parts on connectors that users can touch.
Fast edges radiate interference. Slower edges, short loops, ground planes and filters on cables reduce both what your board emits and what it picks up.
Build in protection early, since fixing it after layout is painful.