nication occurs through the capacitive isolation barrier.
The transceiver meets RS485 and RS422 requirements.
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 cur-
rent 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 Analog
Devices, Inc. All other trademarks are the property of their respective owners.
applicaTions
n
n
n
n
Isolated RS485 Receiver/Driver
RS485 with Large Common Mode Voltage
Breaking RS485 Ground Loops
Multiple Unterminated Line Taps
Typical applicaTion
**
CTX02-14659
1/2 BAT54C
+
10µF
2
2
V
CC
10µF
3
ST2
420kHz
1/2 BAT54C
2
11
GND2
14
V
CC2
+
1
1
V
CC
ST1
A
28
RO
R
B
RO2
16
15
17
LOGIC COMMON
1
FLOATING RS485 COMMON
2
** EATON (888) 414-2645
RO
TWISTED-PAIR
CABLE
RE
DE
DI
27
26
25
4
1
RE
DE
DI
GND
D
Y
Z
SLO
13
12
18
1535fc
1535 TA01
For more information
www.linear.com/LTC1535
1
LTC1535
absoluTe MaxiMuM raTings
(Note 1)
pin conFiguraTion
TOP VIEW
V
CC
1
ST1 2
ST2 3
GND 4
28 RO
27
RE
26 DE
25 DI
V
CC
to GND .................................................................6V
V
CC2
to GND2 ..............................................................8V
Control Input Voltage to GND....... – 0.3V to (V
CC
+ 0.3V)
Driver Input Voltage to GND ..........–0.3V to (V
CC
+ 0.3V)
Driver Output Voltage
(Driver Disabled) to GND2 ...............(V
CC2
– 13V) to 13V
Driver Output Voltage
(Driver Enabled) to GND2................ (V
CC2
– 13V) to 10V
Receiver Input Voltage to GND2 .............................. ±14V
Receiver Output Voltage ...............–0.3V to (V
CC
+ 0.3V)
Operating Temperature Range
LTC1535C ..........................................0°C ≤ T
A
≤ 70°C
LTC1535I ...................................... –40°C ≤ T
A
≤ 85°C
Storage Temperature Range ..................– 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................... 300°C
GND2 11
Z 12
Y 13
V
CC2
14
18
SLO
17 RO2
16 A
15 B
SW PACKAGE
28-LEAD PLASTIC SO
T
JMAX
= 125°C,
θ
JA
= 125°C/W
orDer inForMaTion
LEAD FREE FINISH
LTC1535CSW#PBF
LTC1535ISW#PBF
TAPE AND REEL
LTC1535CSW#TRPBF
LTC1535ISW#TRPBF
http://www.linear.com/product/LTC1535#orderinfo
PART MARKING*
1535
1535
PACKAGE DESCRIPTION
28-Lead Plastic SO
28-Lead Plastic SO
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/.
Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
2
1535fc
For more information
www.linear.com/LTC1535
LTC1535
elecTrical characTerisTics
SYMBOL PARAMETER
V
CC
V
CC2
I
CC
I
CC2
V
OD1
V
OD2
V
OC
I
OSD1
V
IH
V
IL
I
IN
V
TH
∆V
TH
R
IN
V
IOC
V
OH
V
OL
I
OZ
V
OH2
V
OL2
f
SW
R
SWH
R
SWL
I
REL
I
REH
V
UVL
V
UVH
V
ISO
V
CC
Supply Range
V
CC2
Supply Range
V
CC
Supply Current
V
CC2
Supply Current
Differential Driver Output
Differential Driver Output
Driver Output Common Mode Voltage
Driver Short-Circuit Current
V
OUT
= HIGH
V
OUT
= LOW
Logic Input High Voltage
Logic Input Low Voltage
Input Current (A, B)
Receiver Input Threshold
Receiver Input Hysteresis
Receiver Input Impedance
Receiver Input Open Circuit Voltage
RO Output High Voltage
RO Output Low Voltage
Driver Output Leakage
RO2 Output High Voltage
RO2 Output Low Voltage
DC Converter Frequency
DC Converter Impedance High
DC Converter Impedance Low
RE
Output Low Current
RE
Output High Current
Undervoltage Low Threshold
Undervoltage High Threshold
Isolation Voltage
RE
Sink Current, Fault = 0
RE
Source Current, Fault = 1
RE
Fault = 1, (Note 5)
RE
Fault = 0, (Note 5)
1 Minute, (Note 6)
1 Second
I
RO
= – 4mA, V
CC
= 4.5V
I
RO
= 4mA, V
CC
= 4.5V
Driver Disabled (DE = 0)
I
RO2
= – 4mA, V
CC
= 4.5V
I
RO2
= 4mA, V
CC
= 4.5V
l
l
l
l
l
l
l
l
l
l
l
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, V
CC2
= 5V unless otherwise noted.
CONDITIONS
l
l
MIN
4.5
4.5
TYP
MAX
5.5
7.5
UNITS
V
V
mA
mA
mA
V
V
V
Transformer Not Driven (Note 10)
R = 27Ω, Figure 2
No Load
No Load
R = 50Ω (RS422) (Note 2), V
CC2
= 4.5V
R = 27Ω(RS485), Figure 2, V
CC2
= 4.5V
DC Level, R = 50Ω, Figure 2
Driver Enabled (DE = 1)
–7V ≤ V
CM
≤ 10V
–7V ≤ V
CM
≤ 10V
DE, DI,
RE
SLO
DE, DI,
RE
SLO
(Note 3)
–7V ≤ V
CM
≤ 12V, (Note 4)
–7V ≤ V
CM
≤ 12V
0°C ≤ T
A
≤ 70°C
– 40°C ≤ T
A
≤ 85°C
V
IN
= 12V
V
IN
= –7V
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
13
63
7
2
1.5
2.0
60
60
2
4
28
73
12
5
2
2.5
100
100
1.7
2.2
1.7
1.8
0.8
1
0.25
–0.20
3.0
150
150
V
mA
mA
V
V
V
V
mA
mA
mV
mV
mV
kΩ
V
V
–200
10
5
50
3.7
–90
30
30
68
3.4
4.0
0.4
1
–10
70
70
100
0.8
V
µA
V
3.7
290
3.9
0.4
420
4
2.5
0.8
590
6
5
–80
130
4.25
4.40
V
kHz
Ω
Ω
µA
µA
V
V
V
RMS
V
RMS
–40
80
3.70
4.05
2500
3000
–50
100
4.00
4.20
1535fc
For more information
www.linear.com/LTC1535
3
LTC1535
elecTrical characTerisTics
SYMBOL PARAMETER
t
SJ
f
MAX
t
PLH
t
PHL
t
r
, t
f
t
ZH
t
ZL
t
LZ
t
HZ
t
PLH
t
PHL
t
PLH
t
PHL
t
r
, t
f
t
LZ
t
HZ
t
START
t
TOF
Data Sample Jitter
Max Baud Rate
Driver Input to Output
Driver Input to Output
Driver Rise or Fall Time
Driver Enable to Output
Driver Enable to Output
Driver Disable to Output
Driver Disable to Output
Receiver Input to RO
Receiver Input to RO
Receiver Input to RO2
Receiver Input to RO2
Receiver Rise or Fall Time
Receiver Disable to Output
Receiver Disable to Output
Initial Start-Up Time
Data Time-Out Fault
ST1, ST2 Duty Cycle
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, V
CC2
= 5V, R = 27Ω (RS485) unless otherwise noted.
CONDITIONS
Figure 8, (Note 7)
Jitter = 10% Max,
SLO
= 1, (Note 8)
DE = 1,
SLO
= 1, Figure 4, Figure 6
DE = 1,
SLO
= 0, Figure 4, Figure 6
DE = 1,
SLO
= 1, Figure 4, Figure 6
DE = 1,
SLO
= 1, Figure 4, Figure 6
DE = 1,
SLO
= 1, Figure 4, Figure 6
DE = 1,
SLO
= 0, V
CC
= V
CC2
= 4.5V
DI = 1,
SLO
= 1, Figure 5, Figure 7
DI = 0,
SLO
= 1, Figure 5, Figure 7
DI = 0,
SLO
= 1, Figure 5, Figure 7
DI = 1,
SLO
= 1, Figure 5, Figure 7
RE
= 0, Figure 3, Figure 8
RE
= 0, Figure 3, Figure 8
RE
= 0, Figure 3, Figure 8
RE
= 0, Figure 3, Figure 8
RE
= 0, Figure 3, Figure 8
Figure 3, Figure 9
Figure 3, Figure 9
(Note 9)
(Note 9)
0°C ≤ T
A
≤ 70°C
–40°C ≤ T
A
≤ 85°C
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
MIN
250
TYP
250
410
600
1300
600
1300
MAX
285
855
1560
855
1560
100
1000
1400
1400
1300
1300
855
855
UNITS
ns
kBd
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
150
20
500
1000
1000
700
700
600
600
30
30
20
30
30
1200
1200
56
57
%
%
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
RS422 50Ω specification based on RS485 27Ω test.
Note 3:
I
IN
is tested at V
CC2
= 5V, guaranteed by design from
GND2 ≤ V
CC2
≤ 5.25V.
Note 4:
Input fault conditions on the RS485 receiver are detected with a
fixed receiver offset. The offset is such that an input short or open will
result in a high data output.
Note 5:
The low voltage detect faults when V
CC2
or V
CC
drops below
V
UVL
and re-enables when greater than V
UVH
. The fault can be monitored
through the weak driver output on
RE.
Note 6:
Value derived from 1 second test.
Note 7:
The input signals are internally sampled and encoded. The internal
sample rate determines the data output jitter since the internal sampling is
asynchronous with respect to the external data. Nominally, a 4MHz internal
sample rate gives 250ns of sampling uncertainty in the input signals.
Note 8:
The maximum baud rate is 250kBd with 10% sampling jitter.
Lower baud rates have lower jitter.
Note 9:
Start-up time is the time for communication to recover after a fault
condition. Data time-out is the time a fault is indicated on
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