LTC1334 View Datasheet(PDF) - Linear Technology
Part Name
Description
Manufacturer
LTC1334 Datasheet PDF : 16 Pages
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LTC1334
APPLICATI S I FOR ATIO
1
C1
0.1µF 2
VDD
3
0.1µF
INPUT A
4
K1A
LTC1334
28
27 0.1µF
26
25 0.1µF
RX OUT
C2
VCC
5V
PORT 1
120Ω
INPUT B
5
INTERFACE
OUTPUT A
6
5V
K1B
K1*
TX2A-5V
120Ω
7
OUTPUT B
FMMT619**
360k
TERM1
7.5k
13
INPUT A
K2A
24
RX OUT
22
DR IN
8
SEL1
23
DR IN/ENABLE
21 LB
20 ON/OFF
16 RX OUT
PORT 2
INTERFACE
5V
K2*
TX2A-5V
FMMT619**
120Ω
12
INPUT B
11
OUTPUT A
K2B
17 RX OUT
19
DR IN
9
SEL2
120Ω
OUTPUT B
10
14
360k
18
DR IN/ENABLE
15
VEE
0.1µF
TERM2 *AROMAT CORP (800) 276-6289
7.5k
**ZETEX (516) 543-7100
LTC1334 • F12
Figure 12. Multiprotocol Interface
with Optional, Switchable Terminations
Each receiver in the LTC1334 is designed to present one
unit load (5kΩ nominal for RS232 and 12kΩ 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 120Ω 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.
1/2 LTC1334
19
DR IN
11
18
10
DR IN
17
RX OUT
13
16
RX OUT
12
9
RS232/
EIA562
INTERFACE
LINES
1/2 LTC1334
4
24 RX OUT
5
25
RX OUT
6
22 DR IN
7
23 DR IN
8
LTC1334 • F13
Figure 13. Typical Connection for RS232/EIA562 Interface
12
1/2 LTC1334
24
4
RX OUT
5
23
DR ENABLE
6
22
DR IN
7
8
5V
120Ω
120Ω
76
54
1/2
LTC1334
22 23 24 8
DR IN RX OUT
DR ENABLE 5V
1/2 LTC1334
13
17
12
18
11
10
19
9
Figure 14. Typical Connection for RS485 Interface
RX OUT
DR ENABLE
DR IN
5V
LTC1334 F14
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