This slide shows the difference between the systems level ESD protection which is also known as IEC61000-4-2 ESD specification as opposed to device level ESD specification such as HBM, CDM, or MM. If you look at the lower right corner of the graph, the red curve represents the current associated with system level ESD specification. The green curve represents current associated with HBM ESD specification. So, the device IEC specifications can withstand much more ESD stress compared to the HBM device level ESD. Another key difference with the IEC ESD, is that it ensures that when your system is up and running, if the system is zapped with an ESD strike, the device with the IEC ESD specification can tolerate the ES zap and still continue to function. But the device level ESD specifications like HBM, CDM, or MM don’t ensure that the device will continue to function when the system is zapped with a ESD strike. The RS232 devices with the IEC ESD specifications conform to the level 4 standard which is 8 kV contact discharge and a 15 kV air gap discharge.