LTC1535
Isolated RS485 Transceiver
Fea T Descrip T
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UL Rated Isolated RS485: 2500V
The LTC 1535 is an isolated RS485 full-duplex differential
RMS
UL Recognized File #E151738
line transceiver. Isolated RS485 is ideal for systems where
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Eliminates Ground Loops
the ground loop is broken to allow for much larger com-
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250kBd Maximum Data Rate
mon mode voltage ranges. An internal capacitive isola-
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Self-Powered with 420kHz Converter
tion barrier provides 2500V of isolation between the
RMS
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Half- or Full-Duplex
line transceiver and the logic level interface. The powered
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Fail-Safe Output High for Open or
side contains a 420kHz push-pull converter to power the
Shorted Receiver Inputs
isolated RS485 transceiver. Internal full-duplex commu-
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Short-Circuit Current Limit
nication occurs through the capacitive isolation barrier.
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Slow Slew Rate Control
The transceiver meets RS485 and RS422 requirements.
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68k Input Impedance Allows Up to 128 Nodes
The driver and receiver feature three-state outputs, with
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Thermal Shutdown
the driver maintaining high impedance over the entire
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8kV ESD Protection On Driver Outputs and
common mode range. The drivers have short-circuit cur-
Receiver Inputs
rent limits in both directions and a slow slew rate select
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Available in 28-Lead SW Package
to minimize EMI or reflections. The 68k receiver input
allows up to 128 node connections. A fail-safe feature
a T
defaults to a high output state when the receiver inputs
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Isolated RS485 Receiver/Driver
are open or shorted.
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RS485 with Large Common Mode Voltage
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Analog
Devices, Inc. All other trademarks are the property of their respective owners.
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Breaking RS485 Ground Loops
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Multiple Unterminated Line Taps
Typical a T
**
CTX02-14659
1/2 BAT54C
+
10F
2
1/2 BAT54C 2
2 3 11 14
ST1 ST2 GND2 V
CC2
V 1 V
CC CC
420kHz
+
10F
A
1
16
RO TWISTED-PAIR
RO 28 R
LOGIC COMMON
CABLE
B
15
1
FLOATING RS485 COMMON
RO2
17
RE
2
RE 27
** EATON (888) 414-2645
Y
DE 13
26
DE
D
DI Z
DI 25 12
4 GND SLO
18
1
1535 TA01
1535fc
1
For more information www.linear.com/LTC1535
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(Note 1)
V to GND .................................................................6V TOP VIEW
CC
V to GND2 ..............................................................8V
V 1
CC2 28 RO
CC
Control Input Voltage to GND ....... 0.3V to (V + 0.3V) ST1 2
27 RE
CC
ST2 3
Driver Input Voltage to GND ..........0.3V to (V + 0.3V) 26 DE
CC
GND 4
25 DI
Driver Output Voltage
(Driver Disabled) to GND2 ...............(V 13V) to 13V
CC2
Driver Output Voltage
(Driver Enabled) to GND2 ................ (V 13V) to 10V
CC2
Receiver Input Voltage to GND2 .............................. 14V
Receiver Output Voltage ...............0.3V to (V + 0.3V)
CC
Operating Temperature Range
GND2 11
18 SLO
LTC1535C ..........................................0C T 70C
A
Z 12
17 RO2
LTC1535I ...................................... 40C T 85C
A
Y 13
16 A
Storage Temperature Range ..................65C to 150C
V 14
15 B
CC2
Lead Temperature (Soldering, 10 sec) ...................300C
SW PACKAGE
28-LEAD PLASTIC SO
T = 125C, = 125C/W
JMAX JA
o r Der i n F Ma T