LTC486
Quad Low Power
RS485 Driver
FEATURES
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DESCRIPTION
The LTC
®
486 is a low power differential bus/line driver
designed for multipoint data transmission standard RS485
applications with extended common-mode range (12V to
–7V). It also meets RS422 requirements.
The CMOS design offers significant power savings over
its bipolar counterpart without sacrificing ruggedness
against overload or ESD damage.
The driver features 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.
Both AC and DC specifications are guaranteed from 0°C
to 70°C (Commercial), –40°C to 85°C (Industrial), over
the 4.75V to 5.25V supply voltage range.
L,
LT, LTC, LTM, Linear Technology, µModule and the Linear logo are registered trademarks of
Linear Technology Corporation. All other trademarks are the property of their respective owners.
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Very Low Power: I
CC
= 110µA Typ
Designed for RS485 or RS422 Applications
Single 5V Supply
–7V to 12V Bus Common-Mode Range Permits ±7V
GND Difference Between Devices on the Bus
Thermal Shutdown Protection
Power-Up/Down Glitch-Free Driver Outputs Permit
Live Insertion/Removal of Package
Driver Maintains High Impedance in Three-State or
with the Power Off
28ns Typical Driver Propagation Delays with 5ns
Skew
Pin Compatible with the SN75172, DS96172,
µA96172, and DS96F172
APPLICATIONS
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Low Power RS485/RS422 Drivers
Level Translator
TYPICAL APPLICATION
RS485 Length Specification
10k
CABLE LENGTH (FT)
EN
4
DI
1
DRIVER
12
1/4 LTC486
EN
120
4000 FT BELDEN 9841
120
1
EN
4
RECEIVER
3
RO
1k
2
100
1/4 LTC488
486 TA01a
10
10k
100k
1M
2.5M
10M
DATA RATE (bps)
486 TA01b
* APPLIES FOR 24 GAUGE, POLYETHYLENE
DIELECTRIC TWISTED PAIR
486fc
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LTC486
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
DI1
DO1A
DO1B
EN
DO2B
DO2A
DI2
GND
1
2
3
4
5
6
7
8
16 V
CC
15
DI4
14 DO4A
13 DO4B
12 EN
11 DO3B
10 DO3A
9
DI3
Supply Voltage (V
CC
) ................................................12V
Control Input Voltages .......................0.5V to V
CC
+ 0.5V
Driver Input Voltages ...................... –0.5V to V
CC
+ 0.5V
Driver Output Voltages ............................................±14V
Control Input Currents .........................................±25mA
Driver Input Currents ...........................................±25mA
Operating Temperature Range
LTC486C .................................................. 0°C to 70°C
LTC486I................................................ –40°C to 85°C
Storage Temperature Range................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec) .................. 300°C
N PACKAGE
16-LEAD PLASTIC DIP
SW PACKAGE
16-LEAD PLASTIC SO
T
JMAX
= 125°C,
θ
JA
= 70°C/W (N)
T
JMAX
= 150°C,
θ
JA
= 95°C/W (SW)
Consult factory for Military grade parts.
ORDER INFORMATION
LEAD FREE FINISH
LTC486CN#PBF
LTC486CSW#PBF
LTC486IN#PBF
LTC486ISW#PBF
TAPE AND REEL
LTC486CN#TRPBF
LTC486CSW#TRPBF
LTC486IN#TRPBF
LTC486ISW#TRPBF
PART MARKING
LTC486CN
LTC486CSW
LTC486IN
LTC486ISW
PACKAGE DESCRIPTION
16-Lead Plastic DIP
16-Lead Plastic SO
16-Lead Plastic DIP
16-Lead Plastic SO
TEMPERATURE RANGE
0°C to 70°C
0°C to 70°C
–40°C to 85°C
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
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/
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LTC486
DC ELECTRICAL CHARACTERISTICS
SYMBOL
V
OD1
V
OD2
V
OD
V
OC
|V
OC
|
V
IH
V
IL
I
IN1
I
CC
I
OSD1
I
OSD2
I
OZ
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
Supply Current
Driver Short-Circuit Current, V
OUT
= High
Driver Short-Circuit Current, V
OUT
= Low
High Impedance State Output Current
No Load
V
OUT
= –7V
V
OUT
= 12V
V
OUT
= –7V to 12V
Output Enabled
Output Disabled
110
110
100
100
±10
DI, EN,
EN
2.0
0.8
±2
200
200
250
250
±200
V
CC
= 5V ±5%, 0°C ≤ Temperature ≤ 70°C (Commercial), –40°C ≤ Temperature ≤ 85°C (Industrial) (Notes 2, 3)
CONDITIONS
I
OUT
= 0
R = 50Ω; (RS422)
R = 27Ω; (RS485) (Figure 1)
R = 27Ω or R = 50Ω
(Figure 1)
2
1.5
5
0.2
3
0.2
MIN
TYP
MAX
5
UNITS
V
V
V
V
V
V
V
V
µA
µA
µA
mA
mA
µA
SWITCHING CHARACTERISTICS
SYMBOL
t
PLH
t
PHL
t
SKEW
t
r
, t
f
t
ZH
t
ZL
t
LZ
t
HZ
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
V
CC
= 5V ±5%, 0°C ≤ Temperature ≤ 70°C (Commercial), –40°C ≤ Temperature ≤ 85°C (Industrial) (Notes 2, 3)
CONDITIONS
R
DIFF
= 54Ω, C
L1
= C
L2
= 100pF
(Figures 2, 4)
MIN
10
10
5
C
L
= 100pF (Figures 3, 5) S2 Closed
C
L
= 100pF (Figures 3, 5) S1 Closed
C
L
= 15pF (Figures 3, 5) S1 Closed
C
L
= 15pF (Figures 3, 5) S2 Closed
TYP
30
30
5
15
35
35
35
35
MAX
50
50
15
25
70
70
70
70
UNITS
ns
ns
ns
ns
ns
ns
ns
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 V
CC
= 5V and temperature = 25°C.
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LTC486
SWITCHING TIME WAVEFORMS
DI
3V
1.5V
0V
B
A
V
O
–V
O
V
O
1/2 V
O
80%
10%
t
r
t
SKEW
V
DIFF
= V(A) – V(B)
1/2 V
O
90%
20%
t
f
486 F01
f = 1MHz : t
r
< 10ns : t
f
< 10ns
1.5V
t
PHL
t
PLH
t
SKEW
Figure 1. Driver Propagation Delays
EN
3V
1.5V
0V
t
ZL
2.3V
f = 1MHz : t
r
≤ 10ns : t
f
≤ 10ns
1.5V
t
LZ
5V
A, B
V
OL
V
OH
A, B
0V
OUTPUT NORMALLY LOW
0.5V
0.5V
t
HZ
2.3V
t
ZH
OUTPUT NORMALLY HIGH
486 F02
Figure 2. Driver Enable and Disable Times
486fc
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LTC486
TYPICAL PERFORMANCE CHARACTERISTICS
Driver Output High Voltage
vs Output Current T
A
= 25°C
–96
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
64
OUTPUT CURRENT (mA)
0
1
2
3
4
486 G02
Driver Differential Output Voltage
vs Output Current T
A
= 25°C
80
Driver Output Low Voltage
vs Output Current T
A
= 25°C
–72
48
60
–48
32
40
–24
16
20
0
0
1
2
3
4
486 G01
0
0
0
1
2
3
4
486 G03
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
TTL Input Threshold
vs Temperature
1.63
INPUT THRESHOLD VOLTAGE (V)
5
Driver Skew vs Temperature
1.61
TIME (ns)
4
1.59
3
1.57
2
1.55
–50
0
50
100
486 G04
1
–50
0
50
100
486 G05
TEMPERATURE (°C )
TEMPERATURE (°C )
Supply Current vs Temperature
130
DIFFERENTIAL VOLTAGE (V)
SUPPLY CURRENT (µA)
2.3
Driver Differential Output Voltage
vs Temperature R
O
= 54Ω
120
2.1
110
1.9
100
1.7
90
–50
0
50
100
486 G06
1.5
–50
0
50
100
486 G07
TEMPERATURE (°C )
TEMPERATURE (°C )
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Embedded System
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