1
24
V
V
DD CC
Tx1
22
20
18
16
14
3
DI1
DI2
DI3
5
Tx2
Tx3
V
= ± 2 V
in
7
9
DI4
DI5
Tx4
Tx5
11
V
GND
DD
12
Vin
I
Rout
13
Figure 1. Power–Off Source Resistance
Illustrated for MC145408
DRIVERS
+ 3 V
0 V
DI
50%
t
t
r
f
V
OH
OL
90%
Tx
10%
V
t
t
PLH
PHL
RECEIVERS
DRIVERS
+ 3 V
0 V
Rx
50%
+ 3 V
– 3 V
+ 3 V
– 3 V
Tx
t
t
PLH
PHL
90%
t
t
SLH
V
SHL
OH
DO
10%
6 V
or t
V
OL
Slew Rate =
t
t
f
t
SLH
SHL
r
Figure 2. Switching Characteristics
Figure 3. Slew Rate Characteristics
V
PIN DESCRIPTIONS
SS
Most Negative Device Pin
V
CC
Digital Power Supply
The most negative power supply pin, which is typically – 5
to – 12 V.
The digital supply pin, which is connected to the logic
power supply (+ 5.5 V maximum).
Rx1 – Rxn
Receive Data Input Pins
These are the EIA–232–E receive signal inputs. A voltage
between + 3 and + 25 V is decoded as a space, and causes
the corresponding DO pin to swing to ground (0 V). A voltage
between – 3 and – 25 V is decoded as a mark, and causes
GND
Ground
Ground return pin is typically connected to the signal
ground pin of the EIA–232–E connector (Pin 7) as well as to
the logic power supply ground.
the corresponding DO pin to swing to V
.
CC
DO1 – DOn
Data Output Pins
V
DD
Most Positive Device Pin
These are the receiver digital output pins which swing from
V to GND. Each output pin is capable of driving one
The most positive power supply pin, which is typically + 5
to + 12 V.
CC
LSTTL input load.
MOTOROLA
MC145403•MC145404•MC145405•MC145408
5
MOTOROLA [ MOTOROLA ]
