On-Chip system ESD protection design for STN LCD drivers

System ESD protection plays a significant role in many kinds of IC products due to reliability and safety concerns. The reliability requirements and protection methods are also different for various product applications. In this case, the system-level ESD reliability turns our to be critical for an STN LCD driver fabricated in a 9 V/1.0 um-CMOS technology using in panel display application in a cordless phone. The manufactures test results failed the system ESD level spec for air discharge (IEC 1000-4-2: EMC Part4, Session2: Electrostatic discharge immunity test) of minimum 12 KV (no failure) and 15 KV (no reset of panel display): It only passed +3 KV and -10 KV. In this paper the system-level ESD coupling mechanisms of STN LCD drivers are analyzed. From the analysis results, appropriate solutions are derived to enhance the system-level ESD robustness IC to more than 16 KV.