HD66766R Datasheet, PDF (73/97 Pages) Hitachi Semiconductor – 132 x 176-dot Graphics LCD Controller/Driver for 65K Colors

HD66766R
Rev. 1.0-1 / September 2002
Notes: 1. Generate an output voltage (VOUT) from step-up circuit 1 within the range from 4.0 to 5.75V.
2. Do not allow the output voltage (VCH) from step-up circuit 2 to exceed 22 V.
3. Do not allow the output from Vci2 to exceed VOUT voltage .
4. When capacitor with polarity is used, be sure that an inverted voltage is not applied to it in
any state of the system.
5. Vci1 is used as both the reference voltage input and power supply in the step-up circuit.
Keep sufficient LCD drive current.
6. Rated voltage of capacitors possible to be used are as described below. Required voltage
depends on used panels. When actual voltage is less than 16V, capacitors with 16V rated
voltage can be used.
6.3V: VREFM, VciOUT, C11, C12, VOUT, BIASC, Vci2, C21, C22, C23, VSH, VM
25V(16V): VCH, CE, VCL
LCD Drive Voltage
The required voltage can be calculated by applying the following expressions. Drive voltages are
standard; generate a voltage to suit the panel to be used.
1
VSH-VM, VM-VSL
2
1
VCH-VM, VM-VCL
2
2N
N _-1
2N N
N _-1
x Vth
x Vth
Vth: Threshold voltage of the LCD panel to be used.
N: Display duty cycle.
LCD Drive Bias
An optimal bias can be calculated by applying the following expression. The value that has been
calculated is theoretically optimal. If a lower bias value than the optimal value is used to drive the LCD,
contrast may be reduced depending on lighting conditions. However, the power consumption can be
reduced by lowering the drive voltage. Adjust the value according to the system to be used.
1
Bias value =
N
How to determine the VCH voltage
VCH = N_B x N_D2 x VSH
N_B : Bias ratio
N_D2 : Step-up factor of the step-up circuit 2
Contrast adjustment
R_B : Contrast resistance (0.000R to 1.016R)
VSH = VREFM x 2R / (Rb + 2R)
Table 40
CT setting value
CT6 CT5 CT4 CT3 CT2 CT1 CT0 Rb resist value
0
0
000
0
0
0
0
000
0
1
0
0
000
1
0
0
0
000
1
1
0
0
001
0
0
1.016R
1.008R
1.000R
0.992R
0.984R
11
1111
0
11
1111
1
0.008R
0.000R
73
VCI2
VCH
step-up
circuit 2
VCI2=VM N_B
VCH=VM ^{NB N 2}
VREFM
Rb
Rb Resist for adjusting contrast
(0.000R 1.016R)
VSH
R
VM
R
VSL
Figrue 56