Novel Low Power Drivers for Liquid-Crystal Displays

In this paper we focus on a novel generic method to decrease the power dissipation of the large number of output buffers (hundreds to thousands) that drive the large set of pixels, capacitor loads. By simply adding one or more appropriate surface mount inductors to the driver IC, RLC resonant circuits can be periodically constructed to charge and discharge the pixels. When the RLC resonant circuit is interrupted after half an oscillation period, a maximum amount of energy can be recycled, hence minimizing the dynamic power dissipation. After the RLC oscillation is interrupted, the pixels are snapped to their required gray level. We will discuss how the principle of RLC resonant circuits can be implemented for both passive and active matrix LCD’s. The implemented circuits also reduce quiescent current, therefore diminishing the static power. A prototype driver for a 24× 200 passive LCD has been successfully implemented in 2.4mm CMOS technology: in a first experiment energy recycling efficiency of 15% have been demonstrated. Keywords— Energy recycling, output drivers, low power, liquid crystal display