There are two ratings of electrostatic discharges (ESD) caused by human contact: component-level ESD and system-level ESD. Component level ESD immunity rating applies to the manufacturing environment where component assembly, packaging, and shipping are performed in an ESD controlled environment through the application of ESD protective gear. Here, the ESD stress upon a component is significantly reduced and an ESD generator model, known as the human body model (HBM), is used to simulate a charged person’s discharge through component or device under test (DUT) to ground. System level ESD immunity rating applies to the uncontrolled end-user environment where a charged person can subject a system to much higher voltages by touching screw terminals when connecting or disconnecting cables. Here, the ESD generator model is specified by the IEC 61000-4-2 standard that replicates a charged person discharging via a metal object, such as a screw driver, into a grounded electrical system. ESD protection structures designed for IEC61000-4-2 can often tolerate HBM test voltages of up to 2.75x their IEC test voltage. An ESD structure designed for 8kV IEC contact discharge should thus be able to withstand an HBM contact discharge of up to 22kV. The opposite however, that HBM-ESD structures can cope with large IEC-ESD strikes, is unlikely because HBM structures with response times of up to 10ns and significantly lower peak currents are too slow to catch the short front time (<1ns) of an IEC ESD strike and too weak to withstand its high peak current. All Renesas high speed transceivers are rated for the more stringent IEC-ESD requirements.