Grounded? Think Again for EMI Control
Grounded? Think Again for EMI Control
A frequent design error causes electronics to fail EMC tests: pigtail connections between shielded cables and chassis.
Many assume grounding the shield prevents EMI, thinking, “Isn’t the shield now grounded?” Not exactly.
A single-point, high-impedance connection disrupts the Faraday cage effect intended to contain common mode currents.
This allows currents to escape as emissions or makes circuits susceptible to external interference, such as ESD (watch for my upcoming guide).
The chassis does not absorb currents as a sink.
The shield must extend the Faraday cage, protecting internal circuitry and preventing emissions.
The solution: connect the shield to the chassis with a 360° low-impedance connection to maintain a continuous structure that contains electromagnetic energy.
Apply this approach to improve EMC performance.
-Dario
PS. Want more EMI control strategies to help you pass EMC?
Check out my blog here: fresuelectronics.com/blog