TLDD6932COP472 Datasheet, PDF (5/8 Pages) National Semiconductor (TI) – COP472-3 Liquid Crystal Display Controller

Functional Description
The COP472-3 drives 36 bits of display information orga-
nized as twelve segments and three backplanes The
COP472-3 requires 40 information bits 36 data and 4 con-
trol The function of each control bit is described below
Display information format is a function of the LCD intercon-
nections A typical segment backplane configuration is illus-
trated in Figure 5 with this configuration the COP472-3 will
drive 4 digits of 9 segments
To adapt the COP472-3 to any LCD display configuration
the segment backplane multiplex scheme is illustrated in
Table I
Two or more COP472-3 chips can be cascaded to drive
additional segments There is no limit to the number of
COP472-3’s that can be used as long as the output loading
capacitance does not exceed specification
TABLE I COP472-3 Segment Backplane
Multiplex Scheme
Bit Number
Segment
Backplane
Data to
Numeric Display
1
SA1 BPC SH
2
SB1 BPB SG
3
SC1 BPA SF
4
SC1 BPB SE
5
SB1 BPC SD
6
SA1 BPB SC
7
SA1 BPA SB
8
SB1 BPA SA
Digit 1
9
SA2 BPC SH
10
SB2 BPB SG
11
SC2 BPA SF
12
SC2 BPB SE
13
SB2 BPC SD
14
SA2 BPB SC
15
SA2 BPA SB
16
SB2 BPA SA
Digit 2
17
SA3 BPC SH
18
SB3 BPB SG
19
SC3 BPA SF
20
SC3 BPB SE
21
SB3 BPC SD
22
SA3 BPB SC
23
SA3 BPA SB
24
SB3 BPA SA
Digit 3
25
SA4 BPC SH
26
SB4 BPB SG
27
SC4 BPA SF
28
SC4 BPB SE
29
SB4 BPC SD
30
SA4 BPB SC
31
SA4 BPA SB
32
SB4 BPA SA
Digit 4
33
SC1 BPC SPA
34
SC2 BPC SP2
35
SC3 BPC SP3
36
SC4 BPC SP4
37
not used
38
Q6
39
Q7
40
SYNC
Digit 1
Digit 2
Digit 3
Digit 4
SEGMENT DATA BITS
Data is loaded in serially in sets of eight bits Each set of
segment data is in the following format
SA SB SC SD SE SF SG SH
Data is shifted into an eight bit shift register The first bit of
the data is for segment H digit 1 The eighth bit is segment
A digit 1 A set of eight bits is shifted in and then loaded into
the digit one latches The second set of 8 bits is loaded into
digit two latches The third set into digit three latches and
the fourth set is loaded into digit four latches
CONTROL BITS
The fifth set of 8 data bits contains special segment data
and control data in the following format
SYNC Q7 Q6 X SP4 SP3 SP2 SP1
The first four bits shifted in contain the special character
segment data The fifth bit is not used The sixth and sev-
enth bits program the COP472-3 as a stand alone LCD driv-
er or as a master or slave for cascading COP472-3’s BPC
of the master is connected to BPA of each slave The fol-
lowing table summarizes the function of bits six and seven
Q7 Q6 Function BPC Output BPA Output
1 1 Slave
Backplane Oscillator
Output
Input
0 1 Stand Alone Backplane Backplane
Output
Output
1 0 Not Used Internal
Oscillator
Osc Output Input
0 0 Master
Internal
Backplane
Osc Output Output
The eighth bit is used to synchronize two COP472-3’s to
drive an 8 -digit display
5
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