Read Harman Kardon AVR 2550 (serv.man6) Service Manual online
Pin
Pin No.
Function
I/O
Handling when unused
V
FL
1, 13
Driver block power supply connection. (Both pins must be connected.)
—
—
V
DD
60
Logic block power supply connection. Provide a voltage between 4.5 and 5.5 V.
—
—
V
SS
57
Power supply connection. Connect to the ground.
—
—
OSCI
59
Oscillator connection. An oscillator circuit is formed by connecting an external resistor
I
GND
OSCO
58
and capacitor to these pins.
O
OPEN
Display off control input.
BLK
61
BLK = Low (V
SS
) ... Display off. (S1 to S43 and G1 to G11 at V
FL
level.)
I
GND
BLK = High (V
DD
) ... Display on.
Note that serial data can be transferred while the display is turned off.
CL
63
DI
64
I
GND
CE
62
G1 to G11
2 to 12
Digit outputs. These pins are P-channel open drain outputs with pull-down resistors.
O
OPEN
S1 to S43
56 to 14
Segment outputs for displaying the display data transferred by serial data input. These pins
O
OPEN
are P-channel open drain outputs with pull-down resistors.
Serial data transfer inputs. These pins must be connected to the system microcontroller.
CL: Synchronization clock
DI: Transfer data
CE: Chip enable
CL: Synchronization clock
DI: Transfer data
CE: Chip enable
BLOCK DIAGRAM
VFD DRIVER IC PIN FUNCTION (LC75725E) : IC74
Click on the first or last page to see other AVR 2550 (serv.man6) service manuals if exist.