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CHAPTER 12 LCD CONTROLLER/DRIVER
12.2.2 LCD Controller/Driver External Voltage Divider
External voltage divider can also be used with devices that have internal voltage divider.
Display brightness can be adjusted by a variable resistor(VR) connected between the
V
CC
and V3 pins.
■ External voltage divider
When you do not wish to use the internal voltage divider, external voltage divider resistors can be
connected at the LCD drive voltage supply pins (V1 to V3). Figure 12.2-5 "External voltage divider
connection" shows connection for external voltage divider for the two biasing modes, and Table 12.2-1
"LCD drive voltages and biasing modes" lists the corresponding LCD drive voltages.
Figure 12.2-5 External voltage divider connection
Vcc
V3
V2
V1
VR
R
R
V
LCD
Vcc
V3
V2
V1
VR
R
R
V
LCD
R
MB89950/950A series MB89950/950A series
1/2 bias
1/3 bias
Table 12.2-1 LCD drive voltages and biasing modes
Bias
LCD drive voltages
V3 V2 V1
1/2 bias VLCD 1/2VLCD 1/2VLCD
1/3 bias VLCD 2/3VLCD 1/3VLCD
V1 to V3: Voltages at pins V1 to V3.
VLCD: LCD operating voltage