LINER LTC1485 Differential bus transceiver Datasheet

LTC1485
Differential Bus Transceiver
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DESCRIPTIO
FEATURES
■
■
■
■
■
■
■
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■
■
■
■
ESD Protection over ±10kV
Low Power: ICC = 1.8mA Typ
28ns Typical Driver Propagation Delays with
4ns Skew
Designed for RS485 or RS422 Applications
Single 5V Supply
– 7V to 12V Bus Common-Mode Range Permits ±7V
Ground Difference Between Devices on the Bus
Thermal Shutdown Protection
Power-Up/Down Glitch-Free Driver Outputs
Driver Maintains High Impedance in Three-State or
with the Power Off
Combined Impedance of a Driver Output and
Receiver Allows up to 32 Transceivers on the Bus
60mV Typical Input Hysteresis
Pin Compatible with the SN75176A, DS75176A, and
SN75LBC176
■
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. I/O pins are protected against
multiple ESD strikes of over ±10kV.
The receiver has a fail-safe feature which guarantees a
high output state when the inputs are left open.
S
Low Power RS485/RS422 Transceiver
Level Translator
, LTC and LT are registered trademarks of Linear Technology Corporation.
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■
The CMOS with Schottky design offers significant power
savings over its bipolar counterpart without sacrificing
ruggedness against overload or ESD damage.
Both AC and DC specifications are guaranteed from – 40°C
to 85°C and 4.75V to 5.25V supply voltage range.
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APPLICATI
The LTC ®1485 is a low power differential bus/line transceiver designed for multipoint data transmission standard
RS485 applications with extended common-mode range
(12V to – 7V). It also meets the requirements of RS422.
TYPICAL APPLICATI
DE
5V
5V
3
8
8
LTC1485
LTC1485
6
6
DI
4
120Ω
DRIVER
7
RO
1
120Ω
4000 FT 24 GAUGE TWISTED PAIR
DRIVER
RE
RECEIVER
5
4
DI
7
RECEIVER
2
DE
3
5
1
RO
2
RE
1485 TA01
1
LTC1485
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ABSOLUTE
PACKAGE/ORDER I FOR ATIO
RATI GS
(Note 1)
Supply Voltage (VCC) .............................................. 12V
Control Input Voltages ................... – 0.5V to VCC + 0.5V
Control Input Currents ........................ – 50mA to 50mA
Driver Input Voltages ..................... – 0.5V to VCC + 0.5V
Driver Input Currents .......................... – 25mA to 25mA
Driver Output Voltages ......................................... ±14V
Receiver Input Voltages ........................................ ±14V
Receiver Output Voltages .............. – 0.5V to VCC + 0.5V
Operating Temperature Range
LTC1485C .............................................. 0°C to 70°C
LTC1485I .......................................... – 40°C to 85°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec.)................ 300°C
ORDER PART
NUMBER
TOP VIEW
RO 1
DE 3
8 VCC
R
RE 2
7 B
6
D
DI 4
LTC1485CN8
LTC1485IN8
LTC1485CS8
LTC1485IS8
A
5 GND
S8 PACKAGE
N8 PACKAGE
8-LEAD PLASTIC DIP 8-LEAD PLASTIC SOIC
TJMAX = 125°C, θJA = 100°C/ W (N)
TJMAX = 150°C, θJA = 150°C/ W (S)
S8 PART MARKING
1485
1485I
Consult factory for Military grade parts.
DC ELECTRICAL CHARACTERISTICS
VCC = 5V (Notes 2, 3), unless otherwise noted.
SYMBOL
VOD1
VOD2
∆VOD
PARAMETER
Differential Driver Output Voltage (Unloaded)
Differential Driver Output Voltage (With Load)
VINH
VINL
IIN1
IIN2
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)
VTH
∆VTH
VOH
VOL
IOZR
ICC
Differential Input Threshold Voltage for Receiver
Receiver Input Hysteresis
Receiver Output High Voltage
Receiver Output Low Voltage
Three-State Output Current at Receiver
Supply Current
VOC
∆| VOC |
RIN
IOSD1
IOSD2
IOSR
2
Receiver Input Resistance
Driver Short-Circuit Current, VOUT = High
Driver Short-Circuit Current, VOUT = Low
Receiver Short-Circuit Current
CONDITIONS
IO = 0
R = 50Ω, (RS422)
R = 27Ω, (RS485) (Figure 1)
R = 27Ω or R = 50Ω (Figure 1)
MIN
●
●
●
TYP
5
2
1.5
●
R = 27Ω or R = 50Ω (Figure 1)
R = 27Ω or R = 50Ω (Figure 1)
●
DI, DE, RE
DI, DE, RE
DI, DE, RE
VCC = 0V or 5.25V, VIN = 12V
VCC = 0V or 5.25V, VIN = – 7V
– 7V ≤ VCM ≤ 12V
VCM = 0V
IO = – 4mA, VID = 0.2V
IO = 4mA, VID = – 0.2V
VCC = Max 0.4V ≤ VO ≤ 2.4V
No Load; DI = GND or VCC
Outputs Enabled
Outputs Disabled
– 7V ≤ VCM ≤ 12V
VO = – 7V
VO = 10 V
0V ≤ VO ≤ VCC
●
●
●
●
– 0.2
0.4
±1
●
1.8
1.7
●
●
2.3
2.3
12
●
●
●
V
V
3.5
●
●
3
0.2
60
●
●
V
V
V
0.8
±2
1.0
– 0.8
0.2
●
7
UNITS
5
0.2
2.0
●
●
MAX
V
250
250
85
V
V
µA
mA
mA
V
mV
V
V
µA
mA
mA
kΩ
mA
mA
mA
LTC1485
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SWITCHI G CHARACTERISTICS
VCC = 5V (Notes 2, 3), unless otherwise noted.
SYMBOL
tPLH
PARAMETER
Driver Input to Output
tPHL
Driver Input to Output
tSKEW
Driver Output to Output
t r, t f
Driver Rise or Fall Time
t ZH
t ZL
t LZ
t HZ
t PLH
t PHL
t SKEW
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
t ZL
t ZH
t LZ
t HZ
CONDITIONS
RDIFF = 54Ω, CL1 = CL2 = 100pF
(Figures 2, 5)
RDIFF = 54Ω, CL1 = CL2 = 100pF
(Figures 2, 5)
RDIFF = 54Ω, CL1 = CL2 = 100pF
(Figures 2, 5)
RDIFF = 54Ω, CL1 = CL2 = 100pF
(Figures 2, 5)
CL = 100pF (Figures 4, 6) S2 Closed
CL = 100pF (Figures 4, 6) S1 Closed
CL = 15pF (Figures 4, 6) S1 Closed
CL = 15pF (Figures 4, 6) S2 Closed
RDIFF = 54Ω, CL1 = CL2 = 100pF (Figures 2, 7)
RDIFF = 54Ω, CL1 = CL2 = 100pF (Figures 2, 7)
RDIFF = 54Ω, CL1 = CL2 = 100pF (Figures 2, 7)
MIN
10
TYP
30
MAX
50
●
10
30
50
ns
4
10
ns
15
25
ns
40
40
40
40
25
30
5
70
70
70
70
50
55
15
ns
ns
ns
ns
ns
ns
ns
30
30
30
30
45
45
45
45
ns
ns
ns
ns
●
5
●
●
●
●
●
15
20
●
●
●
CL = 15pF (Figures 3, 8) S1 Closed
CL = 15pF (Figures 3, 8) S2 Closed
CL = 15pF (Figures 3, 8) S1 Closed
CL = 15pF (Figures 3, 8) S2 Closed
The ● denotes specifications which apply over the operating temperature
range.
Note 1: Absolute Maximum Ratings are those values beyond which the
safety of the device cannot be guaranteed.
●
●
●
●
●
UNITS
ns
Note 2: All currents into device pins are positive. All currents out of device
pins are negative. All voltages are referenced to device ground unless
otherwise specified.
Note 3: All typicals are given for VCC = 5V and TA = 25°C.
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TYPICAL PERFOR A CE CHARACTERISTICS
Receiver Output Low Voltage vs
Output Current
Receiver Output High Voltage vs
Output Current
36
–18
TA = 25°C
4.8
TA = 25°C
–16
OUTPUT CURRENT (mA)
28
24
20
16
12
8
4
0
4.6
–12
–10
–8
–6
0.5
1.5
1.0
OUTPUT VOLTAGE (V)
2.0
1485 G01
4.2
4.0
3.8
3.6
–4
3.4
–2
3.2
0
0
I = 8mA
4.4
–14
OUTPUT VOLTAGE (V)
32
OUTPUT CURRENT (mA)
Receiver Output High Voltage vs
Temperature
5
4
3
OUTPUT VOLTAGE (V)
2
1485 G02
3.0
–50
–25
0
75
50
25
TEMPERATURE (°C)
100
125
1485 G03
3
LTC1485
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TYPICAL PERFOR A CE CHARACTERISTICS
Receiver Output Low Voltage
vs Temperature
Driver Differential Output Voltage
vs Temperature
Driver Differential Output Voltage
vs Output Current
0.9
I = 8mA
OUTPUT CURRENT (mA)
0.7
OUTPUT VOLTAGE (V)
TA = 25°C
64
0.6
0.5
0.4
0.3
0.2
RL =54Ω
2.4
DIFFERENTIAL VOLTAGE (V)
0.8
48
32
16
2.2
2.0
1.8
0.1
0
–50
0
–25
0
75
50
25
TEMPERATURE (°C)
100
1
0
125
3
2
OUTPUT VOLTAGE (V)
Driver Output Low Voltage vs
Output Current
TA = 25°C
0
–72
–48
–24
0
1
0
3
2
OUTPUT VOLTAGE (V)
1
0
4
3
2
OUTPUT VOLTAGE (V)
4
3
100
125
1485 G10
4
0
75
50
25
TEMPERATURE (°C)
1.8
3
1
–50
–25
0
75
25
50
TEMPERATURE (°C)
100
125
Supply Current vs Temperature
2
2
–25
1485 G09
SUPPLY CURRENT (mA)
4
TIME (ns)
TIME (ns)
5
0
75
25
50
TEMPERATURE (°C)
1.57
Driver Skew vs Temperature
5
–25
1.59
1485 G08
Receiver | tPLH – tPHL | vs
Temperature
1
–50
1.61
1.55
–50
4
1485 G07
125
1.63
INPUT THRESHOLD VOLTAGE (V)
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
20
100
TTL Input Threshold vs
Temperature
TA = 25°C
–96
40
0
75
25
50
TEMPERATURE (°C)
1485 G06
Driver Output High Voltage vs
Output Current
60
–25
1485 G05
1485 G04
80
1.6
–50
4
100
125
1485 G11
DRIVER ENABLED
1.7
1.6
DRIVER DISABLED
1.5
1.4
–50
–25
0
75
25
50
TEMPERATURE (°C)
100
125
1485 G12
LTC1485
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PI FU CTIO S
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.
DI (Pin 4): Driver Input. If the driver outputs are enabled
(DE high), then a low on DI forces the driver outputs A low
and B high. A high on DI will force A high and B 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.
GND (Pin 5): Ground Connection.
DE (Pin 3): Driver Output Enable. A high on DE enables the
driver outputs, A and B. A low input will force the driver
outputs into a high impedance state.
A (Pin 6): Driver Output/Receiver Input.
B (Pin 7): Driver Output/Receiver Input.
VCC (Pin 8): Positive Supply. 4.75V ≤ VCC ≤ 5.25V.
TEST CIRCUITS
A
R
VOD2
A
R
DI
VOC
B
DRIVER
A
CL1
RDIFF
RECEIVER
CL2
RO
15pF
B
B
1485 F02
1485 F01
Figure 1. Driver DC Test Load
S1
RECEIVER
OUTPUT
Figure 2. Driver/Receiver Timing Test Circuit
S1
1k
VCC
VCC
CL
1k
OUTPUT
UNDER TEST
S2
500Ω
CL
S2
1485 F04
1485 F03
Figure 3. Receiver Timing Test Load
Figure 4. Driver Timing Test Load
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LTC1485
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SWITCHI G TI E WAVEFOR S
3V
f = 1MHz; tr ≤ 10ns; t f ≤ 10ns
1.5V
DI
0V
tPHL
VO
V A – VB
1.5V
tPLH
90%
90%
50%
50%
10%
–VO 10%
tf
tr
B
VO
1/2 VO
1/2 VO
A
tSKEW
tSKEW
1485 F05
Figure 5. Driver Propagation Delays
3V
f = 1MHz; tr ≤ 10ns; t f ≤ 10ns
1.5V
DE
1.5V
0V
tZL
tLZ
5V
A,B
2.3V
VOL
OUTPUT NORMALLY LOW
0.5V
OUTPUT NORMALLY HIGH
0.5V
VOH
2.3V
A,B
0V
tZH
1485 F06
tHZ
Figure 6. Driver Enable and Disable Times
INPUT
VOD2
VA – VB
–VOD2
f = 1MHz; tr ≤ 10ns; t f ≤ 10ns
0V
tPLH
tPHL
OUTPUT
VOH
RO
VOL
1.5V
1.5V
1485 F07
Figure 7. Receiver Propagation Delays
6
0V
LTC1485
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SWITCHI G TI E WAVEFOR S
3V
1.5V
RE
0V
1.5V
f = 1MHz; tr ≤ 10ns; t f ≤ 10ns
tZL
tLZ
5V
RO
1.5V
VOL
OUTPUT NORMALLY LOW
0.5V
OUTPUT NORMALLY HIGH
0.5V
VOH
1.5V
RO
0V
tZH
1485 F08
tHZ
Figure 8. Receiver Enable and Disable Times
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APPLICATI
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Typical Application
ends with a resistor equal to their characteristic impedance, typically 120Ω. The input impedance of a receiver is
typically 20k to GND, or 0.6 unit RS485 load, so in practice
50 to 60 transceivers can be connected to the same wires.
The optional shields around the twisted pair help reduce
unwanted noise, and are connected to GND at one end.
A typical connection of the LTC1485 is shown in Figure 9.
Two twisted pair wires connect up to 32 driver/receiver
pairs for half duplex data transmission. There are no
restrictions on where the chips are connected to the wires
and it isn’t necessary to have the chips connected at the
ends. However, the wires must be terminated only at the
LTC1485
LTC1485
RX
1
2
3
RECEIVER
RECEIVER
1
RX
2
3
7
DX
4
DRIVER
DRIVER
120Ω
120Ω
4
DX
6
LTC1485
RECEIVER
1485 F09
1
2
RX
3
7
DRIVER
4
DX
6
Figure 9. Typical Connection
7
LTC1485
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APPLICATI
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10
The LTC1485 has a thermal shutdown feature which
protects the part from excessive power dissipation. If the
outputs of the driver are accidentally shorted to a power
supply or low impedance source, up to 250mA can flow
through the part. The thermal shutdown circuit disables
the driver outputs when the internal temperature reaches
150°C and turns them back on when the temperature
cools to 130°C. If the outputs of two or more LTC1485
drivers are shorted directly, the driver outputs can not
supply enough current to activate the thermal shutdown.
Thus, the thermal shutdown circuit will not prevent contention faults when two drivers are active on the bus at the
same time.
LOSS PER 100 FT (dB)
Thermal Shutdown
1
0.1
0.1
1
10
FREQUENCY (MHz)
100
1485 F10
Figure 10. Attenuation vs Frequency for Belden 9481
10k
The transmission line of choice for RS485 applications is
a twisted pair. There are coaxial cables (twinaxial) made
for this purpose that contain straight pairs, but these are
less flexible, more bulky, and more costly than twisted
pairs. Many cable manufacturers offer a broad range of
120Ω cables designed for RS485 applications.
Losses in a transmission line are a complex combination
of DC conductor loss, AC losses (skin effect), leakage, and
AC losses in the dielectric. In good polyethylene cables
such as the Belden 9841, the conductor losses and dielectric losses are of the same order of magnitude, leading to
relatively low overall loss (Figure 10).
When using low loss cables, Figure 11 can be used as a
guideline for choosing the maximum line length for a given
data rate. With lower quality PVC cables the dielectric loss
factor can be 1000 times worse. PVC twisted pairs have
terrible losses at high data rates (>100kbs), and greatly
reduce the maximum cable length. At low data rates
however, they are acceptable and much more economical.
Cable Termination
The proper termination of the cable is very important. If
the cable is not terminated with its characteristic impedance, distorted waveforms will result. In severe cases,
distorted (false) data and nulls will occur. A quick look at
the output of the driver will tell how well the cable is
terminated. It is best to look at a driver connected to the
8
CABLE LENGTH (FT)
Cables and Data Rate
1k
100
10
10k
100k
1M
DATA RATE (bps)
2.5M
10M
1485 F11
Figure 11. Cable Length vs Data Rate
end of the cable, since this eliminates the possibility of
getting reflections from two directions. Simply look at the
driver output while transmitting square wave data. If the
cable is terminated properly, the waveform will look like
a square wave (Figure12).
If the cable is loaded excessively (47Ω) the signal initially
sees the surge impedance of the cable and jumps to an
initial amplitude. The signal travels down the cable and is
reflected back out of phase because of the mistermination.
When the reflected signal returns to the driver, the amplitude will be lowered. The width of the pedestal is equal to
twice the electrical length of the cable (about 1.5ns/foot).
If the cable is lightly loaded (470Ω) the signal reflects in
phase and increases the amplitude at the driver output. An
input frequency of 30kHz is adequate for tests out to 4000
feet of cable.
LTC1485
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APPLICATI
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PROBE HERE
DX
Rt
DRIVER
RECEIVER
RX
Rt = 120Ω
of the coupling capacitor should therefore be set at 16.3pF
per foot of cable length for 120Ω cables. With the coupling
capacitors in place, power is consumed only on the signal
edges and not when the driver output is idling at a 1 or 0
state. A 100nF capacitor is adequate for lines up to 400 feet
in length. Be aware that the power savings start to decrease once the data rate surpasses 1/(120Ω • C).
Receiver Open-Circuit Fail-Safe
Rt = 47Ω
Rt = 470Ω
1485 F12
Figure 12. Termination Effects
Some data encoding schemes require that the output of
the receiver maintains a known state (usually a logic 1)
when the data is finished transmitting and all drivers on the
line are forced into three-state. The receiver of the LTC1485
has a fail-safe feature which guarantees the output to be in
a logic 1 state when the receiver inputs are left floating
(open-circuit).
If the receiver output must be forced to a known state, the
circuits of Figure 14 can be used.
AC Cable Termination
Cable termination resistors are necessary to prevent unwanted reflections, but they consume power. The typical
differential output voltage of the driver is 2V when the
cable is terminated with two 120Ω resistors, causing
33mA of DC current to flow in the cable when no data is
being sent. This DC current is about 10 times greater than
the supply current of the LTC1485. One way to eliminate
the unwanted current is by AC-coupling the termination
resistors as shown in Figure 13.
5V
110Ω
130Ω
130Ω
110Ω
RECEIVER
RX
RECEIVER
RX
RECEIVER
RX
5V
1.5k
120Ω
120Ω
RECEIVER
RX
1.5k
C
1485 F13
C = LINE LENGTH (FT) • 16.3pF
5V
Figure 13. AC-Coupled Termination
100k
The coupling capacitor must allow high frequency energy
to flow to the termination, but block DC and low frequencies. The dividing line between high and low frequency
depends on the length of the cable. The coupling capacitor
must pass frequencies above the point where the line
represents an electrical one-tenth wavelength. The value
C
120Ω
1485 F14
Figure 14. Forcing “0” When All Drivers Are Off
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LTC1485
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APPLICATI
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The termination resistors are used to generate a DC bias
which forces the receiver output to a known state, in this
case a logic 0. The first method consumes about 208mW
and the second about 8mW. The lowest power solution is
to use an AC termination with a pull-up resistor. Simply
swap the receiver inputs for data protocols ending in
logic 1.
A
120Ω
DRIVER
B
1485 F15
Fault Protection
Figure 15. ESD Protection with TransZorbs
All of LTC’s RS485 products are protected against ESD
transients up to 2kV using the human body model
(100pF, 1.5kΩ). However, some applications need more
protection. The best protection method is to connect a
bidirectional TransZorb® from each line side pin to ground
(Figure 15).
A TransZorb is a silicon transient voltage suppressor that
has exceptional surge handling capabilities: fast response
time and low series resistance. They are available from
General Semiconductor Industries and come in a variety
of breakdown voltages and prices. Be sure to pick a
breakdown voltage higher than the common-mode voltage required for your application (typically 12V). Also,
don’t forget to check how much the added parasitic
capacitance will load down the bus.
TransZorb is a registered trademark of General Instruments, GSI
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TYPICAL APPLICATI
S
RS232 Receiver
RS232
IN
5.6k
RX
RECEIVER
1485 TA02
RS232 to RS485 Level Translator with Hysteresis
220k
A
10k
RS232
IN
120Ω
DRIVER
5.6k
B
1485 TA03
HYSTERESIS = 10k •  VA – VB /R ≈ 19 (kΩ • VOLT)/R
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LTC1485
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PACKAGE DESCRIPTIO
Dimensions in inches (millimeters) unless otherwise noted.
N8 Package
8-Lead Plastic DIP
0.400*
(10.160)
MAX
8
7
6
5
1
2
3
4
0.255 ± 0.015*
(6.477 ± 0.381)
0.300 – 0.325
(7.620 – 8.255)
0.009 – 0.015
(0.229 – 0.381)
(
+0.025
0.325 –0.015
+0.635
8.255
–0.381
)
0.045 – 0.065
(1.143 – 1.651)
0.130 ± 0.005
(3.302 ± 0.127)
0.065
(1.651)
TYP
0.125
(3.175)
MIN
0.045 ± 0.015
(1.143 ± 0.381)
0.100 ± 0.010
(2.540 ± 0.254)
0.018 ± 0.003
(0.457 ± 0.076)
0.015
(0.380)
MIN
N8 0694
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm).
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of circuits as described herein will not infringe on existing patent rights.
11
LTC1485
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PACKAGE DESCRIPTIO
Dimensions in inches (millimeters) unless otherwise noted.
S8 Package
8-Lead Plastic SOIC
0.189 – 0.197*
(4.801 – 5.004)
8
7
6
5
0.150 – 0.157*
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
1
0.010 – 0.020
× 45°
(0.254 – 0.508)
2
3
4
0.053 – 0.069
(1.346 – 1.752)
0.008 – 0.010
(0.203 – 0.254)
0.004 – 0.010
(0.101 – 0.254)
0°– 8° TYP
0.016 – 0.050
0.406 – 1.270
0.014 – 0.019
(0.355 – 0.483)
0.050
(1.270)
BSC
SO8 0294
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006 INCH (0.15mm).
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC486
Quad RS485 Driver
Fits 75172 Pinout, Only 110µA IQ
LTC488
Quad RS485 Receiver
Fits 75173 Pinout, Only 7mA IQ
LTC490
Full Duplex RS485 Transceiver
Fits 75179 Pinout, Only 300µA IQ
LTC1481
Ultra-Low Power Half Duplex RS485 Transceiver
Fits 75176 Pinout, 80µA IQ
12
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7487
(408) 432-1900 FAX: (408) 434-0507 TELEX: 499-3977
●
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sn1485 1485fs LT/GP 0795 2K REV A • PRINTED IN THE
USA
 LINEAR TECHNOLOGY CORPORATION 1995