Block Diagram

Functional Description

GENERAL OVERVIEW

The FPD33684 is a low power, low EMI, 384 output column

driver with 64 gray level capability (6-bit). It provides direct

drive for TFT-LCD displays, eliminating the need for V

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modulation. Direct drive significantly reduces system power

consumption and also reduces component count while pro-

viding superior image quality and cross-talk margin. The

FPD33684 utilizes National’s Charge Conservation Technol-

ogy that recovers energy stored in the capacitance of the

column lines to reduce power consumption further.

The FPD33684 is designed for use in systems using dot

inversion as the method of polarity inversion. Column inver-

sion and N-line inversion are also supported. Other modes of

polarity inversion including line inversion and frame inversion

are not supported.

Digital video data inputs to the FPD33684 are received via a

low power, low EMI Reduced Swing Differential Signaling

64 gray level voltages on each output. Output voltages are

driven with individual high drive, low offset operational am-

plifiers. Data loading and line buffering is accomplished by

means of an internal, bi-directional shift register.

GAMMA CORRECTION

The FPD33684 is designed to offer compatibility with a wide

range of panel gamma characteristics. The output voltage is

tical R-DACs are used to program the output voltages. One

R-DAC provides the high-polarity output voltages (voltages

higher than V

output voltages (voltages lower than V

The FPD33684 is available with two R-DAC resistance curve

options, both of which have been carefully designed to ac-

curately match the natural, inverse gamma of a twisted

nematic (TN) display with a 2.2 gamma transfer character-

istic. A typical TN display, when operated with the FPD33684

drivers will produce a luminance with grayscale characteris-

tics typical of CRT monitors. The R-DAC resistance values

for the FPD33684A are shown in Figure 3 and Figure 4. The

DS200113-6

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