Block Diagram

Applications

The LMC6009 is useful for buffering the nine reference volt-

ages for gamma correction in a TFT-LCD as shown in

Figure 7. The A/B channel inputs allow the user to alternate

two sets of gamma references to compensate for asymmetri-

cal Gamma characteristic during Row Inversion. The

LMC6009 eliminates the need for nine external switches or

an 18-to-9 multiplexer.

Since the buffers in the LMC6009 draw extremely low bias

current (1.5 µA max), large resistance values can be used in

the reference voltage string. This allows the power dissipa-

tion in the gamma reference circuit to be minimized. The

nine buffers are guaranteed to deliver 80 mA to the load, al-

lowing the pixel voltages of the TFT-LCD to settle very

quickly.

DS012533-8

FIGURE 6. Block Diagram of LMC6009

www.national.com

5