ST6280BQ1 STMICROELECTRONICS [STMicroelectronics], ST6280BQ1 Datasheet - Page 58

• Manufacturer Part Number: ST6280BQ1
• Description: 8-BIT OTP/EPROM MCU WITH LCD DRIVER EEPROM AND A/D CONVERTER
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

ST62T80B/E80B
LCD CONTROLLER-DRIVER (Cont”d)
4.7.1 Multiplexing ratio and frame frequency
setting
Up to 16 common plates COM1..COM16 can be
used for multiplexing ratio of 1/8, 1/11 and 1/16.
The selection is made by the bits MUX11 and
MUX16 of the LCDCR as shown in the
Table 21. Multiplexing ratio
If the 1/1 multiplexing ratio is chosen, LCD seg-
ments are refreshed with a frame frequency Flcd
derived from 32Khz clock with a division ratio de-
fined by the bits LF0..LF2 of the LCDCR.
When a higher multiplexing ratio is set, refreshment
frequency is decreased accordingly
Table 22. LCD Frame Frequency Selection
4.7.2 Segment and common plates driving
LCD panels physical structure requires precise
timings and stepped voltage values on common
and segment outputs. Timings are managed by
the LCD controller, while voltages are generated
through an external resistive bridge. In 1/11 and
1/8 multiplexing mode, VLCD 2/5 and VLDCD 3/5
are shorted as seen on
58/80
58
MUX11 MUX16
LF1
0
1
0
1
1
0
1
0
1
LF0
1
0
0
1
1
0
0
1
1
Base
f
(Hz)
128
170
256
512
LCD
1/8 mux.ratio
1/11 mux.ratio
1/16 mux.ratio
-
Display Mode
mux.ratio
Frame Frequency f
Figure
128
170
256
512
1/8
Reserved
mux.ratio
32.
Active backplanes
COM1-8
COM1-16
COM1-16
Reserved
1/11
124
186
372
93
(Table
Table
mux.ratio
F
(Hz)
1/16
22).
128
256
64
85
21.
Figure 32. Bias Config for 1/2 Duty
Note: For display voltages V
tivity of the divider may be too high for some appli-
cations (especially using 1/3 or 1/4 duty display
mode). In that case an external resistive divider
must be used to achieve the desired resistivity.
C5
C4
C3
C2
C1
R5
R4
R3
R1
R2
(1/16 MUX)
1/5 bias
R2 to R5 should be 1K to 200K
C1 to C5 should be 0µF to 0.3 µF
VS
Contrast
VLCD
GND
VLCD 4/5
VLCD 3/5
VLCD 2/5
VLCD 1/5
LCD
C4
R4
C3
C2
R3
R2
C1
R1
(1/11, 1/8 MUX)
< 4.5V the resis-
1/4 bias
VS
GND
Contrast
VLCD
VLCD 4/5
VLCD 3/5
VLCD 2/5
VLCD 1/5
VR001662