
2
FN2954.2
August 24, 2006
Pin Description
PIN NUMBER
TYPE
SYMBOL
DESCRIPTION
16
VCC
VCC: Is the +5V power supply pin. A 0.1μF capacitor between pins 16 and 8 is
recommended for decoupling.
8GND
GROUND
5
I
CP
EXTERNAL CLOCK INPUT
4I
ECP
EXTERNAL CLOCK ENABLE: A low signal on this input allows the baud rate to be
generated from the CP input.
7I
IX
CRYSTAL INPUT
6O
OX
CRYSTAL DRIVE OUTPUT
15
I
IM
MULTIPLEXED INPUT
11, 12, 13, 14
I
S0 - S3
BAUD RATE SELECT INPUTS
9
O
CO
CLOCK OUTPUT
1, 2, 3
O
Q0 - Q2
SCAN COUNTER OUTPUTS
10
O
Z
BIT RATE OUTPUT
CLOCK MODES AND INITIALIZATION
IX
ECP
CP
OPERATION
H
L
Clocked from IX
X
L
Clocked from CP
X
H
Continuous Reset
X
L
Reset During 1st CP = High
Time
H = HIGH Level
L = LOW Level
X = Don’t Care
= Clock Pulse
= 1st HIGH Level Clock Pulse after ECP goes LOW
NOTE: Actual output frequency is 16 times the indicated Output
Rate, assuming a clock frequency of 2.4576MHz.
HD-4702