A single chip driver system for 1.2 inch organic electroluminescent display

A single chip driver system for a passive matrix organic electroluminescent display (PMOELD) with resolution of 128×80 plus 20 icons, has been developed for low cost and small size mobile phone applications. The developed OELD driving single chip comprises a novel current programmable data driver circuit with high voltage current mirror, a scan driver circuit with level shifted high voltage outputs, embedded RAMs, a DC-DC converter that generates a maximum 16 V from a single battery, whose voltage is typically 3.3 V, and digital control circuits that are used for handling display data from an external MCU and control signals. The chip has been fabricated using 0.6 μm CMOS technology with 20 V high voltage devices and it has been attached to the PMOELD panel in a commercial mobile phone by COF (chip on film) technology. The measured minimum power conversion efficiency of the integrated DC-DC converter is 82% and the measured maximum channel-to-channel current variation of the data driver circuit is 5% for a full green image under various luminance conditions. The measured peak luminance of the OELD is 500 cd/m² at the panel power consumption of 0.53 W and the full green image pattern with over 100:1 contrast ratio