LTC1483
Ultra-Low Power RS485 Low EMI
Transceiver with Shutdown
FEATURES
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DESCRIPTIO
s
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Low Power: I
CC
= 120µA Max with Driver Disabled
I
CC
= 500µA Max with Driver Enabled, No Load
1µA Quiescent Current in Shutdown Mode
Controlled Slew Rate Driver for Reduced EMI
Single 5V Supply
Drivers/Receivers Have
±10kV
ESD Protection
– 7V to 12V Common-Mode Range Permits
±7V
Ground Difference Between Devices on the Data Line
Thermal Shutdown Protection
Power Up/Down Glitch-Free Driver Outputs Permit
Live Insertion or Removal of Transceiver
Driver Maintains High Impedance in Three-State
or with the Power Off
Up to 32 Transceivers on the Bus
Pin Compatible with the LTC485
The LTC
®
1483 is an ultra-low power differential line trans-
ceiver designed for data transmission standard RS485
applications with extended common-mode range (– 7V to
12V). It will also meet the requirements of RS422. The
LTC1483 features output drivers with controlled slew rate,
decreasing the EMI radiated from the RS485 lines, and
improving signal fidelity with misterminated lines. The
CMOS design offers significant power savings over its
bipolar counterparts without sacrificing ruggedness against
overload or ESD damage. Typical quiescent current is only
80µA while operating and less than 1µA in shutdown.
The driver and receiver feature three-state outputs, with
the driver outputs maintaining high impedance over the
entire common-mode range. Excessive power dissipation
caused by bus contention or faults is prevented by a
thermal shutdown circuit which forces the driver outputs
into a high impedance state. The receiver has a fail-safe
feature which guarantees a high output state when the
inputs are left open. I/O pins are protected against multiple
ESD strikes of over
±10kV.
The LTC1483 is fully specified over the commercial and
extended industrial temperature range and is available in
8-pin DIP and SO packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATI
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Battery-Powered RS485/RS422 Applications
Low Power RS485/RS422 Transceiver
Level Translator
TYPICAL APPLICATI
RO1
RE1
DE1
DI1
D
R
V
CC1
R
TERM
GND1
DI
A–B
R
TERM
RO2
RE2
DE2
DI2
D
GND2
LTC1483 • TA01
R
V
CC2
RO
U
1483 TA02
UO
UO
1
LTC1483
ABSOLUTE
(Note 1)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
RO 1
RE 2
DE 3
DI 4
N8 PACKAGE
8-LEAD PDIP
D
R
8
7
6
5
V
CC
B
A
GND
Supply Voltage (V
CC
) .............................................. 12V
Control Input Voltage ..................... – 0.5V to V
CC
+ 0.5V
Driver Input Voltage ....................... – 0.5V to V
CC
+ 0.5V
Driver Output Voltage ...........................................
±14V
Receiver Input Voltage ..........................................
±14V
Receiver Output Voltage ................ – 0.5V to V
CC
+ 0.5V
Operating Temperature Range
LTC1483C........................................ 0°C
≤
T
A
≤
70°C
LTC1483I .................................... – 40°C
≤
T
A
≤
85°C
Lead Temperature (Soldering, 10 sec)................. 300°C
ORDER PART
NUMBER
LTC1483CN8
LTC1483IN8
LTC1483CS8
LTC1483IS8
S8 PART MARKING
1483
1483I
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 125°C,
θ
JA
= 130°C/ W (N8)
T
JMAX
= 125°C,
θ
JA
= 150°C/ W (S8)
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
SYMBOL
V
OD1
V
OD2
∆V
OD
V
OC
∆
V
OC
V
IH
V
IL
I
IN1
I
IN2
V
TH
∆V
TH
V
OH
V
OL
I
OZR
R
IN
I
CC
I
SHDN
I
OSD1
I
OSD2
I
OSR
PARAMETER
Differential Driver Output Voltage (Unloaded)
Differential Driver Output Voltage (with Load)
Change in Magnitude of Driver Differential Output
Voltage for Complementary Output States
Driver Common-Mode Output Voltage
Change in Magnitude of Driver Common-Mode
Output Voltage for Complementary Output States
Input High Voltage
Input Low Voltage
Input Current
Input Current (A, B)
Differential Input Threshold Voltage for Receiver
Receiver Input Hysteresis
Receiver Output High Voltage
Receiver Output Low Voltage
Three-State (High Impedance) Output
Current at Receiver
Receiver Input Resistance
Supply Current
Supply Current in Shutdown Mode
Driver Short-Circuit Current, V
OUT
= HIGH
Driver Short-Circuit Current, V
OUT
= LOW
Receiver Short-Circuit Current
V
CC
= 5V, (Notes 2, 3) unless otherwise noted.
CONDITIONS
I
O
= 0
R = 50Ω (RS422)
R = 27Ω (RS485), Figure 1
R = 27Ω or R = 50Ω, Figure 1
R = 27Ω or R = 50Ω, Figure 1
R = 27Ω or R = 50Ω, Figure 1
DE, DI, RE
DE, DI, RE
DE, DI, RE
DE = 0, V
CC
= 0V or 5.25V, V
IN
= 12V
DE = 0, V
CC
= 0V or 5.25V, V
IN
= – 7V
– 7V
≤
V
CM
≤
12V
V
CM
= 0V
I
O
= – 4mA, V
ID
= 200mV
I
O
= 4mA, V
ID
= – 200mV
V
CC
= Max, 0.4V
≤
V
O
≤
2.4V
– 7V
≤
V
CM
≤
12V
No Load, Output Enabled
No Load, Output Disabled
DE = 0, RE = V
CC
– 7V
≤
V
O
≤
12V
– 7V
≤
V
O
≤
12V
0V
≤
V
O
≤
V
CC
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
MIN
2
1.5
TYP
MAX
5
5
0.2
3
0.2
UNITS
V
V
V
V
V
V
V
2
0.8
±2
1.0
– 0.8
– 0.2
45
3.5
0.4
±1
12
25
300
80
1
35
35
7
500
120
10
250
250
85
0.2
2
U
V
µA
mA
mA
V
mV
V
V
µA
kΩ
µA
µA
µA
mA
mA
mA
W
U
U
W W
W
LTC1483
SWITCHI G CHARACTERISTICS
SYMBOL
t
PLH
t
PHL
t
SKEW
t
r
, t
f
t
ZH
t
ZL
t
LZ
t
HZ
t
PLH
t
PHL
t
SKD
t
ZL
t
ZH
t
LZ
t
HZ
f
MAX
t
SHDN
t
ZH(SHDN)
t
ZL(SHDN)
t
ZH(SHDN)
t
ZL(SHDN)
PARAMETER
Driver Input to Output
Driver Input to Output
Driver Output to Output
Driver Rise or Fall Time
Driver Enable to Output High
Driver Enable to Output Low
Driver Disable Time from Low
Driver Disable Time from High
Receiver Input to Output
Receiver Input to Output
t
PLH
– t
PHL
Differential Receiver Skew
Receiver Enable to Output Low
Receiver Enable to Output High
Receiver Disable from Low
Receiver Disable from High
Maximum Data Rate
Time to Shutdown
Driver Enable from Shutdown to Output High
Driver Enable from Shutdown to Output Low
Receiver Enable from Shutdown to Output High
Receiver Enable from Shutdown to Output Low
The
q
denotes specifications which apply over the full operating
temperature range.
Note 1:
Absolute maximum ratings are those beyond which the safety of
the device cannot be guaranteed.
TYPICAL PERFORMANCE CHARACTERISTICS
Supply Current vs Temperature
350
300
THERMAL SHUTDOWN
WITH DRIVER ENABLED
14
12
SUPPLY CURRENT (µA)
DRIVER ENABLED
200
150
100
50
0
–50 –25
DRIVER DISABLED
t
PLH
– t
PHL
(ns)
250
10
8
6
4
2
0
–50 –25
OUTPUT CURRENT (mA)
0
25 50 75 100 125 150 175
TEMPERATURE (°C)
1483 G01
U W
U
V
CC
= 5V, (Notes 2, 3) unless otherwise noted.
MIN
q
q
q
q
CONDITIONS
R
DIFF
= 54Ω, C
L1
= C
L2
= 100pF,
(Figures 3, 5)
LTC1483
TYP
MAX
1200
1200
UNITS
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
kbits/s
ns
ns
ns
ns
ns
150
150
100
150
100
100
150
150
30
30
140
140
13
20
20
20
20
250
50
200
600
1200
1500
1500
1500
1500
200
200
50
50
50
50
600
2000
2000
3500
3500
C
L
= 100pF (Figures 4, 6), S2 Closed
C
L
= 100pF (Figures 4, 6), S1 Closed
C
L
= 15pF (Figures 4, 6), S1 Closed
C
L
= 15pF (Figures 4, 6), S2 Closed
R
DIFF
= 54Ω, C
L1
= C
L2
= 100pF,
(Figures 3, 7)
q
q
q
q
q
q
q
C
RL
= 15pF (Figures 2, 8), S1 Closed
C
RL
= 15pF (Figures 2, 8), S2 Closed
C
RL
= 15pF (Figures 2, 8), S1 Closed
C
RL
= 15pF (Figures 2, 8), S2 Closed
DE = 0, RE =
C
L
= 100pF (Figures 4, 6), S2 Closed
C
L
= 100pF (Figures 4, 6), S1 Closed
C
L
= 15pF (Figures 2, 8), S2 Closed
C
L
= 15pF (Figures 2, 8), S1 Closed
q
q
q
q
q
q
q
q
q
q
Note 2:
All currents into device pins are positive; all currents out ot device
pins are negative. All voltages are referenced to device ground unless
otherwise specified.
Note 3:
All typicals are given for V
CC
= 5V and T
A
= 25°C.
Receiver
t
PLH
– t
PHL
vs
Temperature
70
60
50
40
30
20
10
0
50
25
75
0
TEMPERATURE (°C)
100
125
Driver Differential Output Voltage
vs Output Current
T
A
= 25°C
0
1
4
3
OUTPUT VOLTAGE (V)
2
5
1483 G03
1483 G02
3
LTC1483
TYPICAL PERFORMANCE CHARACTERISTICS
Driver Differential Output Voltage
vs Temperature
2.5
2.4
DIFFERENTIAL VOLTAGE (V)
R
L
= 54Ω
60
OUTPUT CURRENT (mA)
2.3
2.2
2.1
2.0
1.9
1.8
1.7
1.6
1.5
–50
0
50
40
30
20
10
OUTPUT CURRENT (mA)
–25
50
25
0
75
TEMPERATURE (°C)
PIN FUNCTIONS
RO (Pin 1):
Receiver Output. If the receiver output is
enabled (RE low), then if A > B by 200mV, RO will be high.
If A < B by 200mV, then RO will be low.
RE (Pin 2):
Receiver Output Enable. A low enables the
receiver output, RO. A high input forces the receiver
output into a high impedance state.
DE (Pin 3):
Driver Outputs Enable. A high on DE enables
the driver output. A, B and the chip will function as a line
driver. A low input will force the driver outputs into a high
impedance state and the chip will function as a line
receiver. If RE is high and DE is low, the part will enter a low
power (1µA) shutdown state.
DI (Pin 4):
Driver Input. If the driver outputs are enabled
(DE high) then a low on DI forces the outputs A low and B
high. A high on DI with the driver outputs enabled will force
A high and B low.
GND (Pin 5):
Ground.
A (Pin 6):
Driver Output/Receiver Input.
B (Pin 7):
Driver Output/Receiver Input.
V
CC
(Pin 8):
Positive Supply. 4.75V < V
CC
< 5.25V.
FU CTIO TABLES
LTC1483 Transmitting
INPUTS
RE
X
X
0
1
DE
1
1
0
0
DI
1
0
X
X
0
1
Z
Z*
OUTPUTS
B
A
1
0
Z
Z*
RE
0
0
0
1
*Shutdown mode for LTC1483
4
U W
100
125
1483 G04
Driver Output Low Voltage
vs Output Current
70
T
A
= 25°C
0
–10
–20
–30
–40
–50
–60
–70
–80
Driver Output High Voltage
vs Output Current
T
A
= 25°C
0
1
2
OUTPUT VOLTAGE
3
4
1483 G05
–90
0
1
3
2
OUTPUT VOLTAGE (V)
4
5
1483 G06
U
U
U
U
U
LTC1483 Receiving
INPUTS
DE
0
0
0
0
A–B
≥
0.2V
≤
– 0.2V
Inputs Open
X
OUTPUTS
RO
1
0
1
Z*
*Shutdown mode for LTC1483
LTC1483
TEST CIRCUITS
A
R
V
OD
R
B
LTC1483 • F01
RECEIVER
OUTPUT
TEST POINT
S1
1k
V
CC
V
OC
C
RL
1k
S2
LTC1483 • F02
Figure 1. Driver DC Test Load
Figure 2. Receiver Timing Test Load
3V
DE
A
DI
B
R
DIFF
C
L2
C
L1
A
RO
B
RE
LTC1483 • F03
S1
OUTPUT
UNDER TEST
500Ω
S2
C
L
LTC1483 • F04
V
CC
15pF
Figure 3. Driver/Receiver Timing Test Circuit
Figure 4. Driver Timing Test Load
SWITCHI G TI E WAVEFOR S
3V
DI
0V
t
PLH
B
V
O
A
V
O
0V
–V
O
1/2 V
O
10%
t
r
t
SKEW
90%
V
DIFF
= V(A) – V(B)
t
f
t
SKEW
90%
10%
LTC1483 • F05
1.5V
Figure 5. Driver Propagation Delays
3V
DE
0V
5V
A, B
V
OL
V
OH
A, B
0V
2.3V
1.5V
Figure 6. Driver Enable and Disable Times
W
W
U
t
r
≤
10ns, t
f
≤
10ns
t
PHL
1.5V
1/2 V
O
t
r
≤
10ns, t
f
≤
10ns
t
ZL(SHDN)
, t
ZL
t
LZ
1.5V
2.3V
OUTPUT NORMALLY LOW
0.5V
OUTPUT NORMALLY HIGH
t
HZ
0.5V
LTC1483 • F06
t
ZH(SHDN)
, t
ZH
5
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