EMI Bites: ESD Isn’t Just a Contact Problem
Many engineers think ESD only matters when someone touches the device. But the real danger?
ESD can disrupt circuits without any physical contact.
A discharge event creates a fast, high-energy electromagnetic field that radiates through space.
That energy can interfere with nearby electronics—even meters away.
Why this causes problems:
- Fast rise times = high-frequency fields that couple easily into circuits.
- Plastic enclosures offer no shielding; fields pass straight through.
- Nearby circuits can be affected without direct connections.
- Layouts often ignore radiated threats, focusing only on contact protection.
Key Insight:
It’s not just where the spark hits, it’s where the energy travels.
To reduce ESD impact:
- Use shielded enclosures, extra conductive plates, foils, or boxes when possible.
- Keep current loop areas small in critical zones, whether in PCB layout or cables.
- Place ESD protection devices at inputs/outputs, as close as possible to the ESD entry point.
- Ensure solid return and reference planes (RRP).
—Dario
P.S. Want more EMI control strategies to pass EMC?