Casio WK-1800 Service Manual page 20

LCD DRIVER (LSI601: SED1278F2A)
The LCD driver can drive a dot matrix LCD having 40 segment and 16 common lines. The LSI contains 240
graphic symbols in the built-in character generator ROM, and stores 80 characters in the built-in display
data RAM. In accordance with command from the CPU, the LSI is capable of displaying up to 16 characters
simultaneously. The following table shows the pin functions of LSI 601.
Pin No. Terminal
1 ~ 22,
SEG1 ~ SEG40
63 ~ 80
23 VSS
24, 25 OSC1, OSC2
26 ~ 30 V1 ~ V5
31, 32 LP, XSCL
33 VDD
34, 35 FR, DO
36 RS
37 R/W
38 E
39 ~ 42 DB0 ~ DB3
43 ~ 46 DB4 ~ DB7
47 ~ 62 COM1 ~ COM16
REGULATOR IC (IC202: BA9700A)
The regulator IC controls the output voltage by PWM (Pulse Wide Modulation) with outer switching transis-
tors and LC filters (integration circuit).
In/Out
Out Segment signal output
— GND (0 V) source
Terminals for the built-in clock pulse generator. The external re-
In/Out
sistor connected determines the oscillation frequency.
LCD drive voltage input.
In Those voltages are used for generating the stepped pulse of the
LCD drive signals.
— Not used
In LVDD (+5 V) source
— Not used
In Data/command determination terminal.High: data, Low: command
In Read/write terminal. High: read, Low: write
Chip enable signal.
In High: enable, the writing is done at fall edge.
Low: disenable
— Not used. Connected to GND (0 V)
In/Out Data bus
Out Common signal/output
NON
INVERT INVERT
INP 1/2Vret INP
14 13 12
+ –
30k
Error
Amp
30k
PWM
Comparator
Triangle
Oscillator
1 2 3
D-TIME RT CT
CONT
— 19 —
Function
POWER
Vret SW NC VCC
11 10 9
Voltage
Regulator
Vret
4 5 6
FEED OUT NC GND
BACK
8
7