Phenomenological approach for ESD immunity design

It is verified that, a 330 ohm/l50 pF ESD contact discharge simulator met the IEC 801-2 requirements in 150 ps and 350 ps rise time test setups. This same ESD simulator using air discharge in a 150 ps test setup, with a charge voltage, between 2 and 8 kV had a peak current 2 times higher and a rise time of 1/6 of the contact values. A five step design order is presented to achieve cost effective ESD equipment immunity design. The key consideration for obtaining this design is the understanding of the common-mode (CM) ESD current path. A number of examples illustrate this key from the simple reset hardening to the advance concept of ESD differential termination of the converted transient and using a CM inductor to improve the CM rejection in the receptor.<>