Pin Assignment
No. 5732-2/23
LC74789, 74789M, 74789JM
Pin Functions
Pin No.
Pin Name
Function
Notes
1
VSS1
Ground
Ground connection (digital system ground)
2
XtalIN
These pins are used either to connect the crystal and capacitors used to form an external
Crystal oscillator
crystal oscillator circuit to generate the internal synchronizing signals, or to input an external
XtalOUT
(MUTE input)
clock signal (2fsc or 4fsc). As a mask option, the XtalOUT pin can be set to function as the
3
(MUTE)
MUTE input pin. When this pin is set low, the video output is held at the pedestal level. (A pull-
up resistor is built in and the input has hysteresis characteristics.)
Switches the mode between external clock input and crystal oscillator operation. A low level
4
CTRL1
Crystal oscillator input switching
selects crystal oscillator operation and a high level selects external clock input. As a mask
(CHABLK)
(CHABLK output)
option, the CTRL1 input pin can be set to function as the CHABLK (character frame) output.
This is a 3-value output.
5
HFTONOUT
Background line output
Outputs the range signal specified by LNA*, LNB*, and LNC*. Outputs the crystal oscillator
clock when RST is low. (This signal is not output after a reset command is executed.)
6
OSCIN
LC oscillator
Connections for the inductor and capacitor that form the character output dot clock generation
7
OSCOUT
oscillator
Outputs the state of the external synchronizing signal presence/absence judgment. Outputs a
8
SYNCJDG
External synchronizing signal
high level when synchronizing signals are present.
judgment output
Outputs the dot clock (LC oscillator) when RST is low. (This signal is not output on command
resets.)
9
CS
Enable input
Serial data input circuit enable pin. Serial data input is enabled when a low level is input.
A pull-up resistor is built in. (This input has hysteresis characteristics.)
10
SCLK
Clock input
Serial data input circuit clock input.
A pull-up resistor is built in. (This input has hysteresis characteristics.)
11
SIN
Data input
Serial data input.
A pull-up resistor is built in. (This input has hysteresis characteristics.)
12
VDD2
Power supply
Composite video signal level adjustment power supply (analog system power supply)
Continued on next page.
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