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CHAPTER 12 LCD CONTROLLER/DRIVER
12.2.1 LCD Controller/Driver Internal Voltage Divider
LCD driver supply voltage can be taken from an internal voltage divider (external
voltage divider may also be used).
■ Internal voltage divider
In these devices, external voltage divider may also be connected at pins V1 through V3.
The selection of internal or external voltage divider is made by the drive supply voltage control bit of LCD
control register (LCDR: VSEL). VSEL = "1" connects the internal voltage divider. Set VSEL to "1" when
you want to use the internal voltage divider only (when no external voltage divider is connected).
The LCD enable is inactive when LCD operation is stopped (LCDR: MS1, MS0 = "00
B
"), or in stop mode
(STBC: STP = "1"). Pin V2 and V1 should be shorted together when using the 1/2 bias setting.
Figure 12.2-2 "Internal voltage divider equivalent circuit" shows an equivalent circuit of the internal
voltage divider.
Figure 12.2-2 Internal voltage divider equivalent circuit
V3
V2
V1
N-ch
P-ch
R
N-ch
P-ch
R
N-ch
P-ch
R
N-ch
V
2
V
1
V
3
VSEL
Short together when
using 1/2 bias.
MB89950/950A series
LCD enable
V
1
to V
3
: Voltages at V1 to V3 pins.