LTC1535
Isolated RS485 Transceiver
FEATURES
DESCRIPTION
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The LTC®1535 is an isolated RS485 full-duplex differential
line transceiver. Isolated RS485 is ideal for systems where
the ground loop is broken to allow for much larger common
mode voltage ranges. An internal capacitive isolation barrier
provides 2500VRMS of isolation between the line transceiver
and the logic level interface. The powered side contains a
420kHz push-pull converter to power the isolated RS485
transceiver. Internal full-duplex communication occurs
through the capacitive isolation barrier. The transceiver
meets RS485 and RS422 requirements.
UL Rated Isolated RS485: 2500VRMS
UL Recognized
File #E151738
Eliminates Ground Loops
250kBd Maximum Data Rate
Self-Powered with 420kHz Converter
Half- or Full-Duplex
Fail-Safe Output High for Open or
Shorted Receiver Inputs
Short-Circuit Current Limit
Slow Slew Rate Control
68kΩ Input Impedance Allows Up to 128 Nodes
Thermal Shutdown
8kV ESD Protection On Driver Outputs and
Receiver Inputs
Available in 28-Lead SW Package
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APPLICATIONS
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Isolated RS485 Receiver/Driver
RS485 with Large Common Mode Voltage
Breaking RS485 Ground Loops
Multiple Unterminated Line Taps
The driver and receiver feature three-state outputs, with
the driver maintaining high impedance over the entire
common mode range. The drivers have short-circuit
current limits in both directions and a slow slew rate select
to minimize EMI or reflections. The 68kΩ receiver input
allows up to 128 node connections. A fail-safe feature
defaults to a high output state when the receiver inputs
are open or shorted.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
**
CTX02-14659
1/2 BAT54C
+
10μF
2
1/2 BAT54C
2
VCC
1
+
VCC
ST1
3
2
11
14
GND2
ST2
VCC2
420kHz
10μF
A
1
LOGIC COMMON
28
RO
RO
R
B
1
FLOATING RS485 COMMON
2
RE
27
DE
26
RO2
RE
** COOPER (888) 414-2645
25
DI
4
1
Y
DE
D
DI
GND
Z
SLO
16
15
TWISTED-PAIR
CABLE
17
13
12
18
1535 TA01
1535fb
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