EMC immunity is the ability for an equipment to properly operate in its electromagnetic environment by limiting the reception of electromagnetic energy that may cause physical damages. Electrostatic Discharge called ESD fall into this category. ESD can be either conducted under the form of a Transient Voltage, but it can be also radiated due to its fast-raising time, generating harmonics, powerful enough to generate erratic behavior of your application by coupling with other signals. It means that ESD is a threat against which your printed Circuit Boards must be protected.
How to select the right ESD protection?
To select the right ESD protection, 3 parameters must be validated.
1. The ESD protection must be transparent for the application.
To do that the protection capacitance must be in-line with application bandwidth if analog or the data rate if digital.
2. The ESD protection must be efficient when ESD event is present.
To select the protection with a good clamping, it is recommended to select an ESD protection with a VRM just above the maximum line voltage.
3. To avoid snap-back protection latch-up once turned on, the holding voltage must be higher than DC line voltage to ensure a good system integration.
ESD protection type of products
Offering both uni-directional and bi-directional diode arrays, ST’s ESD portfolio supports many personal electronics devices including smartphones, audio accessories and IoT devices; industrial applications such as metering or medical electronics; and communication equipment for home gateways, servers and storage devices, to name just a few.
They are available in a wide range of SMD packages including the smallest single-line packages such as 01005 and 0201 as well as the popular SOT23, 0402 (SOD882), QFN, and DFN packages often used in industrial applications.
ESD protection benefits
They also offer robustness and reliable clamping capabilities against electrical overstress in compliance with the following standards:
- IEC 61000-4-2 for ESD protection (exceeds Level 4), up to ±30 kV (air discharge) and ±30 kV (contact discharge)
- IEC 61000-4-5 for surge immunity
Example of ESD protections and EMI filters around MCU
