We have developed the 1.8-inch 128(×RGB)×160 full-color passive matrix organic electro-luminescent display (PMOELD) for IMT-2000 terminals and its driver chipset. A PWM (Pulse Width Modulated) current-controlled gray scale method with a new pre-charging architecture, which considers the power limitation of the battery-operated systems, has been proposed for the accurate gray scale with securing safe operation. The measured results show that the proposed gray scale method has the merits of linear gray scale realization and over 15% power saving effect in comparison with the conventional method.