LTC1485
Differential
Bus Transceiver
FEATURES
DESCRIPTION
ESD Protection Over ±10kV
nn Low Power: I
CC = 1.8mA Typ
nn 28ns Typical Driver Propagation Delays
with 4ns Skew
nn Designed for RS485 or RS422 Applications
nn Single 5V Supply
nn −7V to 12V Bus Common-Mode Range Permits
±7V Ground Difference Between Devices on the Bus
nn Thermal Shutdown Protection
nn Power-Up/Down Glitch-Free Driver Outputs
nn Driver Maintains High Impedance in Three-State or
with the Power Off
nn Combined Impedance of a Driver Output and
Receiver Allows up to 32 Transceivers on the Bus
nn 60mV Typical Input Hysteresis
nn Pin-Compatible with the SN75176A, DS75176A,
and SN75LBC176
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.
nn
The CMOS with Schottky design offers significant power
savings over its bipolar counterpart without sacrificing
ruggedness against overload or ESD damage.
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.
Both AC and DC specifications are guaranteed from –40°C
to 85°C and 4.75V to 5.25V supply voltage range.
APPLICATIONS
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.
Low Power RS485/RS422 Transceiver
nn Level Translator
nn
TYPICAL APPLICATION
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
4
DI
7
RECEIVER
2
DE
3
RECEIVER
5
5
RE
1
RO
2
RE
1485 TA01
1485fb
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1
LTC1485
ABSOLUTE MAXIMUM RATINGS
PIN CONFIGURATION
(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
TOP VIEW
RO 1
R
RE 2
DE 3
DI 4
D
8 VCC
7 B
6
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)
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC1485CN8
LTC1485CN8
1485
8-Lead Plastic DIP
0°C to 70°C
LTC1485IN8
LTC1485IN8
1485I
8-Lead Plastic DIP
–40°C to 85°C
LTC1485CS8
LTC1485CS8
1485
8-Lead Plastic SOIC
0°C to 70°C
LTC1485IS8
LTC1485IS8
1485I
8-Lead Plastic SOIC
–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
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LTC1485
DC ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 5V (Notes 2, 3).
SYMBOL
PARAMETER
CONDITIONS
VOD1
Differential Driver Output Voltage (Unloaded)
IO = 0
l
MIN
VOD2
Differential Driver Output Voltage (With Load)
R = 50Ω, (RS422)
R = 27Ω, (RS485) (Figure 1)
l
l
∆VOD
Change in Magnitude of Driver Differential
R = 27Ω or R = 50Ω (Figure 1)
Output Voltage for Complementary Output States
VOC
Driver Common-Mode Output Voltage
TYP
MAX
5
2
1.5
UNITS
V
5
V
V
l
0.2
V
R = 27Ω or R = 50Ω (Figure 1)
l
3
V
∆|VOC|
Change in Magnitude of Driver Common-Mode
R = 27Ω or R = 50Ω (Figure 1)
Output Voltage for Complementary Output States
l
0.2
V
VINH
Input High Voltage
DI, DE, RE
l
2.0
V
VINL
Input Low Voltage
DI, DE, RE
l
0.8
V
IIN1
Input Current
DI, DE, RE
l
±2
µA
IIN2
Input Current (A, B)
VCC = 0V or 5.25V, VIN = 12V
VCC = 0V or 5.25V, VIN = −7V
l
l
1.0
−0.8
mA
mA
VTH
Differential Input Threshold Voltage for Receiver
–7V ≤ VCM ≤ 12V
l
0.2
V
∆VTH
Receiver Input Hysteresis
VCM = 0V
l
VOH
Receiver Output High Voltage
IO = –4mA, VID = 0.2V
l
−0.2
60
mV
3.5
V
VOL
Receiver Output Low Voltage
IO = 4mA, VID = –0.2V
l
0.4
V
IOZR
Three-State Output Current at Receiver
VCC = Max 0.4V ≤ VO ≤ 2.4V
l
±1
µA
ICC
Supply Current
No Load; DI = GND or VCC
Outputs Enabled
Outputs Disabled
l
l
2.3
2.3
mA
mA
1.8
1.7
RIN
Receiver Input Resistance
–7V ≤ VCM ≤ 12V
l
IOSD1
Driver Short-Circuit Current, VOUT = High
VO = –7V
l
250
mA
IOSD2
Driver Short-Circuit Current, VOUT = Low
VO = 10 V
l
250
mA
IOSR
Receiver Short-Circuit Current
0V ≤ VO ≤ VCC
l
85
mA
12
7
kΩ
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3
LTC1485
SWITCHING CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 5V (Notes 2, 3).
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
tPLH
Driver Input to Output
RDIFF = 54Ω, CL1 = CL2 = 100pF
(Figures 2, 5)
tPHL
Driver Input to Output
tSKEW
l
10
30
50
ns
RDIFF = 54Ω, CL1 = CL2 = 100pF
(Figures 2, 5)
l
10
30
50
ns
Driver Output to Output
RDIFF = 54Ω, CL1 = CL2 = 100pF
(Figures 2, 5)
l
4
10
ns
tr, tf
Driver Rise or Fall Time
RDIFF = 54Ω, CL1 = CL2 = 100pF
(Figures 2, 5)
l
15
25
ns
tZH
Driver Enable to Output High
CL = 100pF (Figures 4, 6) S2 Closed
l
40
70
ns
tZL
Driver Enable to Output Low
CL = 100pF (Figures 4, 6) S1 Closed
l
40
70
ns
tLZ
Driver Disable Time from Low
CL = 15pF (Figures 4, 6) S1 Closed
l
40
70
ns
tHZ
Driver Disable Time from High
CL = 15pF (Figures 4, 6) S2 Closed
l
40
70
ns
5
UNITS
tPLH
Receiver Input to Output
RDIFF = 54Ω, CL1 = CL2 = 100pF (Figures 2, 7)
l
15
25
50
ns
tPHL
Receiver Input to Output
RDIFF = 54Ω, CL1 = CL2 = 100pF (Figures 2, 7)
l
20
30
55
ns
tSKEW
| tPLH – tPHL |
Differential Receiver Skew
RDIFF = 54Ω, CL1 = CL2 = 100pF (Figures 2, 7)
l
5
15
ns
tZL
Receiver Enable to Output Low
CL = 15pF (Figures 3, 8) S1 Closed
l
30
45
ns
tZH
Receiver Enable to Output High
CL = 15pF (Figures 3, 8) S2 Closed
l
30
45
ns
tLZ
Receiver Disable from Low
CL = 15pF (Figures 3, 8) S1 Closed
l
30
45
ns
tHZ
Receiver Disable from High
CL = 15pF (Figures 3, 8) S2 Closed
l
30
45
ns
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
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.
TYPICAL PERFORMANCE CHARACTERISTICS
Receiver Output Low Voltage vs
Output Current
Receiver Output High Voltage vs
Output Current
–18
36
TA = 25°C
24
20
16
12
8
–12
–10
–8
–6
–4
4
0
0
1.5
1.0
OUTPUT VOLTAGE (V)
2.0
1485 G01
I = 8mA
4.4
–14
–2
0.5
4.6
OUTPUT VOLTAGE (V)
28
0
4.8
TA = 25°C
–16
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
32
4
Receiver Output High Voltage vs
Temperature
4.2
4.0
3.8
3.6
3.4
3.2
5
4
3
OUTPUT VOLTAGE (V)
2
1485 G02
3.0
–50
–25
0
75
25
50
TEMPERATURE (°C)
100
125
1485 G03
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LTC1485
TYPICAL PERFORMANCE CHARACTERISTICS
Receiver Output Low Voltage
vs Temperature
Driver Differential Output Voltage
vs Output Current
Driver Differential Output Voltage
vs Temperature
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
75
25
50
TEMPERATURE (°C)
–25
100
0
125
1
0
3
2
OUTPUT VOLTAGE (V)
1485 G04
TA = 25°C
0
1
0
3
2
OUTPUT VOLTAGE (V)
–72
–48
–24
0
4
1
0
3
2
OUTPUT VOLTAGE (V)
4
3
2
125
1485 G10
0
75
25
50
TEMPERATURE (°C)
1.8
3
1
–50
–25
0
75
25
50
TEMPERATURE (°C)
100
125
Supply Current vs Temperature
2
100
–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
Driver Output Low Voltage vs
Output Current
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
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5
LTC1485
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.
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 CIRCUIT
A
R
VOD2
A
R
VOC
B
DI
CL1
A
RDIFF
DRIVER
RECEIVER
CL2
B
RO
15pF
B
1485 F01
1485 F02
Figure 1. Driver DC Test Load
S1
RECEIVER
OUTPUT
CL
1k
1k
Figure 2. Driver/Receiver Timing Test Circuit
S1
VCC
VCC
OUTPUT
UNDER TEST
S2
500Ω
CL
S2
1485 F04
1485 F03
Figure 3. Receiver Timing Test Load
6
Figure 4. Driver Timing Test Load
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LTC1485
SWITCHING TIME WAVEFORMS
3V
f = 1MHz; tr ≤ 10ns; t f ≤ 10ns
1.5V
DI
0V
tPLH
tPHL
VO
VA – VB
–VO 10%
B
VO
1.5V
90%
90%
50%
50%
10%
tf
tr
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
VOH
2.3V
A,B
0V
OUTPUT NORMALLY LOW
0.5V
OUTPUT NORMALLY HIGH
0.5V
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
0V
1.5V
1.5V
1485 F07
Figure 7. Receiver Propagation Delays
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7
LTC1485
SWITCHING TIME WAVEFORMS
3V
1.5V
RE
0V
1.5V
f = 1MHz; tr ≤ 10ns; t f ≤ 10ns
tZL
tLZ
5V
RO
1.5V
VOL
VOH
1.5V
RO
0V
OUTPUT NORMALLY LOW
0.5V
OUTPUT NORMALLY HIGH
0.5V
tZH
1485 F08
tHZ
Figure 8. Receiver Enable and Disable Times
APPLICATIONS INFORMATION
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
2
RX
3
7
DX
4
DRIVER
DRIVER
120Ω
120Ω
4
DX
6
LTC1485
RECEIVER
1485 F09
1
2
RX
3
7
6
DRIVER
4
DX
Figure 9. Typical Connection
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LTC1485
APPLICATIONS INFORMATION
Thermal Shutdown
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)
10
1
0.1
0.1
1
10
FREQUENCY (MHz)
100
1485 F10
Figure 10. Attenuation vs Frequency for Belden 9481
Cables and Data Rate
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
end of the cable, since this eliminates the possibility of
CABLE LENGTH (FT)
10k
1k
100
10
10k
100k
1M
DATA RATE (bps)
2.5M
10M
1485 F11
Figure 11. Cable Length vs Data Rate
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 (Figure 12).
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.
For more information www.linear.com/LTC1485
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9
LTC1485
APPLICATIONS INFORMATION
PROBE HERE
DX
Rt
DRIVER
RECEIVER
RX
Rt = 120Ω
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
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.
Figure 12. Termination Effects
AC Cable Termination
5V
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.
110Ω
130Ω
130Ω
110Ω
RECEIVER
RX
RECEIVER
RX
RECEIVER
RX
5V
1.5k
120Ω
120Ω
RECEIVER
1.5k
RX
C
5V
1485 F13
C = LINE LENGTH (FT) • 16.3pF
100k
Figure 13. AC-Coupled Termination
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
of the coupling capacitor should therefore be set at 16.3pF
10
C
120Ω
1485 F14
Figure 14. Forcing “0” When All Drivers Are Off
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LTC1485
APPLICATIONS INFORMATION
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
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
Figure 15. ESD Protection with TransZorbs
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.
TYPICAL APPLICATIONS
RS232 Receiver
RS232
IN
RX
RECEIVER
5.6k
1485 TA02
RS232 to RS485 Level Translator with Hysteresis
220k
A
10k
RS232
IN
5.6k
120Ω
DRIVER
B
1485 TA03
HYSTERESIS = 10k • |VA – VB| /R ≈ 19 (kΩ • VOLT)/R
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11
LTC1485
PACKAGE DESCRIPTION
Please refer to http://www.linear.com/product/LTC1485#packaging for the most recent package drawings.
N Package
8-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510 Rev I)
.400*
(10.160)
MAX
8
7
6
5
1
2
3
4
.255 ±.015*
(6.477 ±0.381)
.300 – .325
(7.620 – 8.255)
.008 – .015
(0.203 – 0.381)
(
+.035
.325 –.015
8.255
+0.889
–0.381
)
.045 – .065
(1.143 – 1.651)
.065
(1.651)
TYP
.100
(2.54)
BSC
.130 ±.005
(3.302 ±0.127)
.120
(3.048) .020
MIN
(0.508)
MIN
.018 ±.003
N8 REV I 0711
(0.457 ±0.076)
NOTE:
1. DIMENSIONS ARE
INCHES
MILLIMETERS
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)
12
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For more information www.linear.com/LTC1485
LTC1485
REVISION HISTORY
(Revision history begins at Rev B)
REV
DATE
DESCRIPTION
B
11/15
Updated format
Updated package drawings
PAGE NUMBER
1-12
11, 12
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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 its circuits
as described
herein will not infringe on existing patent rights.
For more
information
www.linear.com/LTC1485
13
LTC1485
PACKAGE DESCRIPTION
Please refer to http://www.linear.com/product/LTC1485#packaging for the most recent package drawings.
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610 Rev G)
.189 – .197
(4.801 – 5.004)
NOTE 3
.045 ±.005
.050 BSC
8
.245
MIN
.160 ±.005
6
5
.150 – .157
(3.810 – 3.988)
NOTE 3
.228 – .244
(5.791 – 6.197)
.030 ±.005
TYP
1
RECOMMENDED SOLDER PAD LAYOUT
.010 – .020
× 45°
(0.254 – 0.508)
.008 – .010
(0.203 – 0.254)
7
2
3
4
.053 – .069
(1.346 – 1.752)
.004 – .010
(0.101 – 0.254)
0°– 8° TYP
.016 – .050
(0.406 – 1.270)
NOTE:
1. DIMENSIONS IN
.014 – .019
(0.355 – 0.483)
TYP
INCHES
(MILLIMETERS)
2. DRAWING NOT TO SCALE
3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
4. PIN 1 CAN BE BEVEL EDGE OR A DIMPLE
.050
(1.270)
BSC
SO8 REV G 0212
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
14 Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
For more information www.linear.com/LTC1485
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com/LTC1485
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LT 1115 REV B • PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 1995
工商网监
湘ICP备2023018690号
