S6B0755 Datasheet, PDF (32/68 Pages) Samsung semiconductor – 128 SEG / 65 COM DRIVER & CONTROLLER FOR STN LCD

S6B0755
PRELIMINARY SPEC. VER. 1.0
128 SEG / 65 COM DRIVER & CONTROLLER FOR STN LCD
In Case of Using External Resistors, Ra and Rb (INTRS = "L")
When INTRS pin is "L", it is necessary to connect external regulator resistor Ra between VR and VSS, and Rb
between V0 and VR.
Example: For the following requirements
1. LCD driver voltage, V0 = 10V
2. 6-bit reference voltage register = (1, 0, 0, 0, 0, 0)
3. Maximum current flowing Ra, Rb = 1 uA
From Eq. 1
Rb
10 = (1 +  ) x VEV
Ra
[V] ------ (Eq. 3)
From Eq. 2
(63 - 32)
VEV = (1 -  ) x 2.1 = 1.79 [V] ------ (Eq. 4)
210
From requirement 3.
10
 = 1 [uA] ------ (Eq. 5)
Ra + Rb
From equations Eq. 3, 4 and 5
Ra = 1.79 [MΩ]
Rb = 8.21 [MΩ]
Table 12 Shows the Range of V0 depending on the above Requirements.
Table 12. The Range of V0
Electronic volume level
0
.......
32
.......
V0
8.21
.......
10.00
.......
63
11.73
Voltage Follower Circuits
VLCD voltage (V0) is resistively divided into four voltage levels (V1, V2, V3 and V4), and those output impedance
are converted by the Voltage Follower for increasing drive capability. Table 13 shows the relationship between V1
to V4 level and each duty ratio.
Table 13
LCD bias
V1
V2
V3
V4
Remarks
1/N
(N-1)/N x V0
(N-1)/N x V0
2/N x V0
1/N x V0
N = 4 to 9
29