Datasheet

SN75C185
LOW-POWER MULTIPLE DRIVERS AND RECEIVERS
SLLS065F – AUGUST 1989 – REVISED JANUARY 2000
9
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
11
12
13
14
15
16
17
18
19
20
GND
RY5
DA3
RY4
DA2
DA1
RY3
RY2
RY1
V
CC
V
SS
RA5
DY3
RA4
DY2
DY1
RA3
RA2
RA1
V
DD
10
9
8
7
6
5
4
3
2
1
43
37
40
13
36
11
41
42
RI
DTR
CTS
SO
RTS
SI
DSR
DCD
R1
DTR
CTS
TX
RTS
RX
DSR
DCD
SN75C185
5 V
TL16C450
ACE
1
5
6
9
12 V
–12 V
TIA/EIA-232-F
DB9S
Connector
Figure 7. Typical Connection
The SN75C185 supports data rates up to 120 kbit/s over a 3-meter cable. Laboratory experiments show that,
with C
L
= 500 pF and R
L
= 3 kΩ (minimum RS-232 input resistance load), the device can support this data rate.
The 500-pF load approximates a typical 3-meter cable because the maximum RS-232 specification is 2500 pF
(or about 15 meters). Figure 8 shows the test circuit used. Temperature was varied from 0°C to 70°C for the
experiment.
NOTES: A. The pulse generator has the following characteristics: PRR = 60 kHz (120 kbit/s), Z
O
= 50 Ω.
B. V
CC
= 5 V, V
DD
= 12 V, V
SS
= –12 V.
C
L
R
L
Input
Output
Pulse
Generator
(See Note A)
V
SS
V
CC
V
DD
Figure 8. Data-Rate Test Circuit