ESD Protection Design for Touch Panel Control IC Against Latchup-Like Failure Induced by System-Level ESD Test

Due to the snapback holding voltage of high-voltage (HV) nMOS smaller than the maximum operating voltage, the traditional power-rail electrostatic discharge (ESD) clamp circuit implemented with such HV nMOS suffered latchup-like failure in a touch panel control IC after the system-level ESD test. A modified design on the power-rail ESD clamp circuit is proposed and verified in an HV CMOS process with 12 V double-diffused drain MOS device. With the holding voltage greater than the maximum operating voltage of 12 V, the touch panel equipped with the modified control IC can successfully pass the system-level ESD test of ±15 kV in the air-discharge test mode to meet the level 4 of IEC 61000-4-2 industry specification.