Overview
The LC74751 is a CMOS LSI that supports on-screen
display of characters and patterns on a TV screen under
the control of a microcontroller. The LC74751 includes an
on-chip character ROM that provides 128 characters in a
12
18 dot format. This IC supports display of up to 12
lines of 24 characters each for a maximum of 288
characters.
Features
Display format: 24 characters by 12 rows
Characters displayed: Up to 288 characters
Display control ROM (line ROM): ROM for 64 lines
(Control in line units: lines consisting of 24 characters)
Display RAM: 176 characters (Used for the specification
of user-defined characters.)
Character format: 12 (horizontal)
18 (vertical) dots
Characters in font: 128
Character sizes: Four sizes each in the horizontal and
vertical directions
Initial display positions: 64 horizontal positions and 64
vertical positions
Blinking: Specifiable in character units
Blinking types:
-- Two periods supported: 1.0 second and 0.5 second
-- Three duty types supported: 25%, 50%, and 75%
Blanking: Over the whole font (12
18 dots)
Background color
-- 8 background colors (in internal synchronization
mode): 4fsc (NTSC/PAL/PAL-M/PAL-N)
-- 4 background colors (in internal synchronization
mode): 2fsc (NTSC)
-- Single background color (blue) (in internal
synchronization mode): 2fsc (PAL/PAL-M/PAL-N)
External control input: Serial data input
Synchronizing signals: Supports switching between
internal and external synchronizing signals.
On-chip sync separator circuit
Video output: Composite video output in the NTSC,
PAL, PAL-M, or PAL-N format
Superimpose function: Superimposes the character
output on the composite video output.
Package Dimensions
unit: mm
3059-DIP22S
CMOS LSI
Ordering number : EN
*
5396
83096HA (OT) No. 5396-1/15
Preliminary
SANYO: DIP22S
[LC74751]
SANYO Electric Co.,Ltd. Semiconductor Bussiness Headquarters
TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110 JAPAN
On-Screen Display LSI
LC74751
Pin Assignment
No. 5396-2/15
LC74751
Parameter
Symbol
Conditions
Ratings
Unit
min
typ
max
Supply voltage
V
DD1
V
DD1
4.5
5.0
5.5
V
V
DD2
V
DD2
4.5
5.0
1.27 V
DD1
V
Input high-level voltage
V
IH
CS, SIN, RST, SCLK, and SEP
IN
0.8 V
DD1
V
DD1
+ 0.3
V
Input low-level voltage
V
IL
CS, SIN, RST, SCLK, and SEP
IN
V
SS
0.3
0.2 V
DD1
V
Composite video input voltage
V
IN1
CV
IN
2 Vp-p
V
V
IN2
SYN
IN
2 Vp-p
2.5 Vp-p
V
f
OSC1
Crystal oscillator pins (NTSC: 2fsc mode)
7.15909
MHz
f
OSC2
Crystal oscillator pins (NTSC: 4fsc mode)
14.31818
MHz
Oscillator frequency
f
OSC3
Crystal oscillator pins (PAL: 4fsc mode)
17.73447
MHz
f
OSC4
Crystal oscillator pins (PAL-M: 4fsc mode)
14.30244
MHz
f
OSC5
Crystal oscillator pins (PAL-N: 4fsc mode)
14.32822
MHz
f
OSC6
LC oscillator pin (When an LC oscillator is used)
5
7
11
MHz
Allowable Operating Ranges
Specifications
Absolute Maximum Ratings
Parameter
Symbol
Conditions
Ratings
Unit
Supply voltage
V
DD
V
DD1
and V
DD2
V
SS
0.3 to V
SS
+7.0
V
Input voltage
V
IN
All input pins
V
SS
0.3 to V
DD
+0.3
V
Output voltage
V
OUT
V
SS
0.3 to V
DD
+0.3
V
Allowable power dissipation
Pd max
Ta = 25C
300
mW
Operating temperature
Topr
30 to +70
C
Storage temperature
Tstg
40 to +125
C
Parameter
Symbol
Conditions
Ratings
Unit
min
typ
max
Output off leakage current
I
leak
CV
OUT
10
A
Output high-level voltage
V
OH1
SEP
OUT
: V
DD1
= 4.5 V, I
OH
= 1.0 mA
3.5
V
Output low-level voltage
V
OL1
SEP
OUT
: V
DD1
= 4.5 V, I
OL
= 1.0 mA
1.0
V
Input current
I
IH
CS, SIN, RST, SCLK, and SEP
IN
: V
IN
= V
DD1
1
A
I
IL
OSC
IN
: V
IN
= V
SS
1
A
Operating current drain
I
DD1
V
DD1
; All outputs open, Xtal: 17.734MHz, LC = 7MHz
10
mA
I
DD2
V
DD2
; V
DD2
= 5.0 V
15
mA
Electrical Characteristics
at Ta = 30 to +70C, V
DD1
= 5 V unless otherwise specified
No. 5396-3/15
LC74751
Parameter
Symbol
Conditions
Ratings
Unit
min
typ
max
Minimum input pulse width
t
W(SCLK)
SCLK
200
ns
t
W(CS)
CS (the period when CS is high)
1
s
Data setup time
t
SU(CS)
CS
200
ns
t
SU(SIN)
SIN
200
ns
Data hold time
t
h(CS)
CS
2
s
t
h(SIN)
SIN
200
ns
One-word write time
t
word
The time to write 16 bits of data
10
s
t
wt
The time to write data to RAM
1
s
Timing Characteristics
at Ta = 30 to +70C, V
DD1
= 50.5 V
Serial Data Input Timing
Pin Functions
No. 5396-4/15
LC74751
Pin no.
Pin
Function
Notes
1
V
SS
Ground
Ground (digital system ground)
2
Xtal
IN
Crystal oscillator
Connections for the crystal and capacitors used to form the crystal oscillator for generating
3
Xtal
OUT
internal synchronizing signals.
4
TEST
Test output
Test data output
5
RST
Reset input
System reset input (This input has hysteresis characteristics.)
6
SCLK
Clock input
Clock input for the serial data input function (This input has hysteresis characteristics.)
7
SIN
Data input
Serial data input (This input has hysteresis characteristics.)
Data is input in 16-bit units.
8
CS
Enable input
Serial data input enable input (This input has hysteresis characteristics.)
Serial data input is enabled when this pin is low.
9
LVBK
Blanking level adjustment input
Level input signal used to adjust the blanking level.
10
LVCHA
Character level adjustment input
Level input signal used to adjust the character level.
11
V
DD2
Power supply
Composite video signal adjustment power supply (analog system power supply)
12
CV
OUT
Video signal output
Composite video signal output
13
NC
This pin must be either connected to ground or left open.
14
CV
IN
Video signal input
Composite video signal input
15
V
DD1
Power supply
Power supply (+5 V)
16
SYN
IN
Sync separator circuit input
Input to the composite sync signal sync separator circuit
17
SEP
C
Sync separator circuit adjustment
Sync separator circuit adjustment
18
SEP
OUT
Composite sync signal output
Sync separator circuit composite sync signal output
19
SEP
IN
Vertical synchronizing signal input
Connect an integration circuit between the SEP
OUT
pin and this pin, which inputs the vertical
synchronizing signal, to integrate the output signal from the SEP
OUT
pin.
20
OSC
OUT
LC oscillator
Connections for the coil and capacitor that form the oscillator used to generate the character
21
OSC
IN
output dot clock.
22
V
DD1
Power supply (+5 V)
Power supply (+5 V)
System Block Diagram
Display Screen Structure
The display mode has a 24-character by 12-row format.
The maximum number of characters that can be displayed is 288.
When character sizes are enlarged, the maximum number of characters that can be displayed is reduced.
Display ROM (12-line specification) and display RAM (for 176 characters)
Specify fixed characters in the display line ROM.
Application programs use the display RAM to specify characters for sections of the display in which the characters
change.
No. 5396-5/15
LC74751
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