ST7571 Sitronix Technology, ST7571 Datasheet - Page 26

• Manufacturer Part Number: ST7571
• Description: 4 Gray Scale Dot Matrix LCD Controller/Driver
• Manufacturer: Sitronix Technology

www.DataSheet4U.com
ST7571
7.4 POWER SUPPLY CIRCUITS
The Power Supply circuits generate the voltage levels necessary to drive liquid crystal driver circuits with low power
consumption and the fewest components. There are voltage converter circuits, voltage regulator circuits, and voltage
follower circuits. They are controlled by power control instruction.
Voltage Regulator Circuits
The internal Voltage Regulator circuit provides the liquid crystal operating voltage (V0) by adjusting resistors (SRR and EV).
The parameter “SRR” can be set by “Select Regulator Register”.
The parameter “EV” can be set by “Set Electronic Volume Register”, and the range of EV is 0~63.
V0 = SRR x (1 - ——————) x 2.1
Fig. 18 shows V0 voltage measured by adjusting regulator register ratio and 6-bit electronic registers for each temperature
coefficient at Ta = 25°C. The recommended range of EV setting is level 16 ~ 47.
Ver 1.5a
(Select Regulator Ratio)
SRR
16
14
12
10
8
6
4
2
0
(63- EV)
210
Table 5 Internal Regulator Ratio depending on 3-bit Data (R2 R1 R0)
0 0 0
2.3
Fig. 18 Electronic Volume Level (25°C)
0 0 1
3.0
0 1 0
26/76
3.7
3-bit data settings (R2 R1 R0)
0 1 1
4.4
1 0 0
5.1
1 0 1
5.8
1 1 0
000
001
010
011
100
101
110
111
6.5
2009/7/21
1 1 1
7.2