LTC1334 LINER [Linear Technology], LTC1334 Datasheet - Page 12

• Manufacturer Part Number: LTC1334
• Description: Single 5V RS232/RS485 Multiprotocol Transceiver
• Manufacturer: LINER [Linear Technology]

LTC1334
A
12
FMMT619**
FMMT619**
INTERFACE
TX2A-5V
INTERFACE
TX2A-5V
PPLICATI
PORT 1
PORT 2
K1*
K2*
5V
5V
C1
OUTPUT A
OUTPUT B
OUTPUT A
OUTPUT B
360k
360k
INPUT A
INPUT B
7.5k
Figure 12. Multiprotocol Interface
with Optional, Switchable Terminations
7.5k
INPUT A
INPUT B
0.1 F
DR ENABLE
V
120
120
120
120
DD
K1A
K1B
K2A
K2B
O
0.1 F
TERM2
TERM1
RX OUT
DR IN
U
5V
13
12
11
10
14
S
1
2
3
4
5
6
7
**
*
24
23
22
AROMAT CORP [phone]
ZETEX [phone]
8
1/2 LTC1334
I FOR ATIO
U
LTC1334
5
6
4
7
W
Figure 14. Typical Connection for RS485 Interface
0.1 F
15
28
27
26
25
24
22
8
23
21
20
16
17
19
9
18
120
RX OUT
RX OUT
DR IN
SEL1
DR IN/ENABLE
ON/OFF
RX OUT
RX OUT
DR IN
SEL2
DR IN/ENABLE
LB
0.1 F
0.1 F
U
LTC1334 • F12
V
EE
C2
DR IN
V
5V
CC
DR ENABLE
7 6
22
23
RX OUT
Each receiver in the LTC1334 is designed to present one
unit load (5k nominal for RS232 and 12k minimum for
RS485) to the cable. Some RS485 and RS422 applications
call for terminations, but these are only necessary at two
nodes in the system and they must be disconnected when
operating in the RS232 mode. A relay is the simplest, low-
est cost method of switching terminations. In Figure 12
TERM1 and TERM2 select 120 terminations as needed.
If terminations are needed in all RS485/RS422 applica-
tions, no extra control signals are required; simply con-
nect TERM1 and TERM2 to SEL1 and SEL2.
Typical Applications
A typical RS232/EIA562 interface application is shown in
Figure 13 with the LTC1334.
A typical connection for a RS485 transceiver is shown in
Figure 14. A twisted pair of wires connects up to 32 drivers
and receivers for half duplex multipoint data transmission.
The wires must be terminated at both ends with resistors
equal to the wire’s characteristic impedance. An optional
shield around the twisted pair helps to reduce unwanted
noise and should be connected to ground at only one end.
5 4
24 8
Figure 13. Typical Connection for RS232/EIA562 Interface
5V
RX OUT
RX OUT
1/2
LTC1334
DR IN
DR IN
120
19
18
17
16
9
1/2 LTC1334
13
12
11
10
11
10
13
12
1/2 LTC1334
INTERFACE
RS232/
EIA562
LINES
17
18
19
9
RX OUT
DR ENABLE
5V
DR IN
4
5
6
7
1/2 LTC1334
LTC1334 F14
LTC1334 • F13
24
25
22
23
8
RX OUT
RX OUT
DR IN
DR IN