ST7528 Sitronix, ST7528 Datasheet - Page 42

• Manufacturer Part Number: ST7528
• Description: 16 Gray Scale Dot Matrix LCD Controller
• Manufacturer: Sitronix

ST7528
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
10 = (1 +
From Eq. 1
VEV = (1 -
From requirement 3.
10
Ra + Rb
From equations Eq. 3, 4 and 5
Ra = 1.79 [M ]
Rb = 8.21 [M ]
Table 7 Shows the Range of V0 depending on the above Requirements.
V0
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 8 shows the relationship between V1 to V4 level
and each duty ratio.
LCD bias
1/N
Ver2.3
Rb
Ra
= 1 [uA] ------ (Eq. 5)
(63 - 32)
210
) x VEV [V] ------ (Eq. 3)
Electronic volume level
0
8.21
V1
(N-1)/N x V0
Table 8 The Relationship between V1 to V4 Level and Each Duty Ratio
) x 2.1 = 1.79 [V] ------ (Eq. 4)
.......
.......
V2
(N-2)/N x V0
Table 7 The Range of V0
42/97
32
10.00
V3
2/N x V0
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.......
.......
V4
1/N x V0
63
11.73
N = 5 to 12
Remarks
2007/1/3
Datasheet pdf - http://www.DataSheet4U.net/