PD16724_15 datasheet(9/26 Pages) RENESAS

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Data Sheet S16086EJ1V0DS

µµµµPD16724

4. RELATIONSHIP BETWEEN INPUT DATA AND OUTPUT VOLTAGE VALUE

The

µPD16724 incorporates a 8-bit D/A converter which can output respectively gray scale voltages of differing

polarity with respect to the LCD’s counter electrode voltage as shown in Figure 4

−1. The D/A converter consists of

ladder resistors and switches.

The ladder resistors (r0 to r253) are designed so that the ratio of LCD panel (

γ -compensated voltages to V0’-V255’ and

V0”-V255” is almost equivalent. For the 2 sets of nine

γ -compensated power supplies, V0-V8 and V9-V17, respectively,

input gray scale voltages of the same polarity with respect to the 0.5 VDD2.

Figure 4

−1 shows the relationship between the driving voltages such as liquid-crystal driving voltages VDD2, VSS2 and

0.5 VDD2, and

γ -corrected voltages V0-V17 and the input data. Be sure to maintain the voltage relationships below.

VDD2

− 0.2 V ≥ V0 > V1 > V2 > V3 > V4 > V5 > V6 > V7 > V8 ≥ 0.5 VDD2 + 0.5 V

0.5 VDD2

− 0.5 V ≥ V9 > V10 > V11 > V12 > V13 > V14 > V15 > V16 > V17 ≥ 0.5 VSS2 + 0.2 V

VDD2

− 0.2 V ≥ V8 > V7 > V6 > V5 > V4 > V3 > V2 > V1 > V0 ≥ 0.5 VDD2 + 0.5 V

0.5 VDD2

− 0.5 V ≥ V17 > V16 > V15 > V14 > V13 > V12 > V11 > V10 > V9 ≥ 0.5 VSS2 + 0.2 V

Also, V7-V8, V8-V9 and V9-V10 are left open in the IC. Be sure to input the gray scale level power supply at a

constant level to the all pins.

Figures 4

−2 and 4−3 show the relation ship between the input data and the output voltage and the resistance values

of the resistor strings.

Figure 4

−−−−1. Relationship between Input Data and γγγγ -corrected Power Supplies

VDD2

0.5 VDD2

V10

V11

V12

V13

V14

V15

VSS2

00 01

Input Data (HEX)

0.2 V

0.5 V

V17

V16

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