Lcd Controller/Driver Internal Voltage Divider - Fujitsu Semiconductor Controller MB89950/950A Hardware Manual

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).
I 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
(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.
V
3
V
2
V
1
VSEL
V to V : Voltages at V1 to V3 pins.
1 3
Figure 12.2-2 Internal voltage divider equivalent circuit
P-ch
P-ch
P-ch
LCD enable
MB89950/950A series
CHAPTER 12 LCD CONTROLLER/DRIVER
V3
R
N-ch
V2
R
N-ch
V1
R
N-ch
N-ch
"), or in stop mode
B
Short together when
using 1/2 bias.
237