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LTC491CS#PBF

P1-P3P4-P6P7-P9P10-P12
1
LTC491
491fa
■
Low Power: I
CC
= 300µA Typical
■
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 Permit
Live Insertion or Removal of Package
■
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
■
70mV Typical Input Hysteresis
■
28ns Typical Driver Propagation Delays with 5ns
Skew for 2.5MB Operation
■
Pin Compatible with the SN75180
■
Available in 14-Lead PDIP and SO Packages
Differential Driver and
Receiver Pair
The LTC
®
491 is a low power differential bus/line trans-
ceiver designed for multipoint data transmission standard
RS485 applications with extended common mode range
(12V to –7V). It also meets the requirements of RS422.
The CMOS 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.
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 0°C to
70°C and 4.75V to 5.25V supply voltage range.
■
Low Power RS485/RS422 Transceiver
■
Level Translator
LTC491 • TA01
120Ω 120Ω
120Ω 120Ω
4000 FT 24 GAUGE TWISTED PAIR
4000 FT 24 GAUGE TWISTED PAIR
RECEIVER
LTC491
DRIVER
RECEIVER
LTC491
DRIVER
R
D
R
D
5
2
11
12
10
9
4
DE
3
REB
DE
REB
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
, LTC and LT are registered trademarks of Linear Technology Corporation.
LTC491
2
491fa
A
U
G
W
A
W
U
W
ARB
S
O
LU
T
EXI T
I
S
WU
U
PACKAGE
/
O
RDER I FOR ATIO
ORDER PART
NUMBER
LTC491CN
LTC491CS
LTC491IN
LTC491IS
(Note 1)
Supply Voltage (V
CC
) ............................................... 12V
Control Input Voltages .................... –0.5V to V
CC
+ 0.5V
Control Input Currents .......................... –50mA to 50mA
Driver Input Voltages ...................... –0.5V to V
CC
+ 0.5V
Driver Input Currents ............................ –25mA to 25mA
Driver Output Voltages .......................................... ±14V
Receiver Input Voltages ......................................... ±14V
Receiver Output Voltages ............... –0.5V to V
CC
+ 0.5V
Operating Temperature Range
LTC491C ................................................. 0°C to 70°C
LTC491I.............................................. –40°C to 85°C
Storage Temperature Range ................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)..................300°C
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V ±5%
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
OD1
Differential Driver Output Voltage (Unloaded) I
O
= 0 ● 5V
V
OD2
Differential Driver Output Voltage (With load) R = 50Ω; (RS422) ● 2V
R = 27Ω; (RS485) (Figure 1) ● 1.5 5 V
∆V
OD
Change in Magnitude of Driver Differential Output R = 27Ω or R = 50Ω (Figure 1) ● 0.2 V
Voltage for Complementary Output States
V
OC
Driver Common Mode Output Voltage ● 3V
∆ V
OC
Change in Magnitude of Driver Common Mode ● 0.2 V
Output Voltage for Complementary Output States
V
IH
Input High Voltage D, DE, REB ● 2.0 V
V
IL
Input Low Voltage ● 0.8 V
l
IN1
Input Current ● ±2 µA
l
IN2
Input Current (A, B) V
CC
= 0V or 5.25V V
IN
= 12V ● 1.0 mA
V
IN
= –7V ● –0.8 mA
V
TH
Differential Input Threshold Voltage for Receiver –7V ≤ V
CM
≤ 12V ● –0.2 0.2 V
∆V
TH
Receiver Input Hysteresis V
CM
= 0V ● 70 mV
V
OH
Receiver Output High Voltage I
O
= –4mA, V
ID
= 0.2V ● 3.5 V
V
OL
Receiver Output Low Voltage I
O
= 4mA, V
ID
= –0.2V ● 0.4 V
I
OZR
Three-State Output Current at Receiver V
CC
= Max 0.4V ≤ V
O
≤ 2.4V ● ±1 µA
I
CC
Supply Current No Load; D = GND, Outputs Enabled ● 300 500 µA
or V
CC
Outputs Disabled ● 300 500 µA
R
IN
Receiver Input Resistance –7V ≤ V
CM
≤ 12V ● 12 kΩ
I
OSD1
Driver Short Circuit Current, V
OUT
= High V
O
= –7V ● 100 250 mA
I
OSD2
Driver Short Circuit Current, V
OUT
= Low V
O
= 12V ● 100 250 mA
I
OSR
Receiver Short Circuit Current 0V ≤ V
O
≤ V
CC
● 785mA
I
OZ
Driver Three-State Output Current V
O
= –7V to 12V ● ±2 ±200 µA
14
13
12
11
10
9
87
6
5
4
3
2
1
TOP VIEW
S PACKAGE
14-LEAD PLASTIC SO
NC
N PACKAGE
14-LEAD PDIP
Y
NC
Z
B
NC
V
CC
D
GND
GND
R
REB
DE
A
R
D
T
JMAX
= 100°C, θ
JA
= 90°C/W (N)
T
JMAX
= 100°C, θ
JA
= 110°C/W (S)
Consult LTC Marketing for parts specified with wider operating temperature ranges.
DC ELECTRICAL CHARACTERISTICS
3
LTC491
491fa
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
t
PLH
Driver Input to Output R
DIFF
= 54Ω, C
L1
= C
L2
= 100pF ● 10 30 50 ns
t
PHL
Driver Input to Output ● 10 30 50 ns
t
SKEW
Driver Output to Output ● 5ns
t
r
, t
f
Driver Rise or Fall Time ● 51525 ns
t
ZH
Driver Enable to Output High C
L
= 100pF (Figures 4, 6) S2 Closed ● 40 70 ns
t
ZL
Driver Enable to Output Low C
L
= 100pF (Figures 4, 6) S1 Closed ● 40 70 ns
t
LZ
Driver Disable Time From Low C
L
= 15pF (Figures 4, 6) S1 Closed ● 40 70 ns
t
HZ
Driver Disable Time From High C
L
= 15pF (Figures 4, 6) S2 Closed ● 40 70 ns
t
PLH
Receiver Input to Output R
DIFF
= 54Ω, C
L1
= C
L2
= 100pF ● 40 70 150 ns
t
PHL
Receiver Input to Output ● 40 70 150 ns
t
SKD
t
PLH
– t
PHL
Differential Receiver Skew ● 13 ns
t
ZL
Receiver Enable to Output Low C
L
= 15pF (Figures 3, 8) S1 Closed ● 20 50 ns
t
ZH
Receiver Enable to Output High C
L
= 15pF (Figures 3, 8) S2 Closed ● 20 50 ns
t
LZ
Receiver Disable From Low C
L
= 15pF (Figures 3, 8) S1 Closed ● 20 50 ns
t
HZ
Receiver Disable From High C
L
= 15pF (Figures 3, 8) S2 Closed ● 20 50 ns
S
U
GC CHARA TERIST
ICS
WI
TCH
I
(Figures 2, 5)
(Figures 2, 7)
Note 3: All typicals are given for V
CC
= 5V and temperature = 25°C.Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.
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.
NC (Pin 1): Not Connected.
R (Pin 2): Receiver Output. If the receiver output is enabled
(REB low), then if A > B by 200mV, R will be high. If A < B
by 200mV, then R will be low.
REB (Pin 3): Receiver Output Enable. A low enables the
receiver output, R. A high input forces the receiver output
into a high impedance state.
DE (Pin 4): Driver Output Enable. A high on DE enables the
driver outputs, Y and Z. A low input forces the driver
outputs into a high impedance state.
D (Pin 5): Driver Input. If the driver outputs are enabled
(DE high), then a low on D forces the driver outputs Y low
and Z high. A high on D will force Y high and Z low.
GND (Pin 6): Ground Connection.
GND (Pin 7): Ground Connection.
NC (Pin 8): Not Connected.
Y (Pin 9): Driver Output.
Z (Pin 10): Driver Output.
B (Pin 11): Receiver Input.
A (Pin 12): Receiver Input.
NC (Pin 13): Not Connected.
V
CC
(Pin 14): Positive Supply; 4.75V ≤ V
CC
≤ 5.25V.
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V ±5%
UU
U
PI FU CTIO S
P1-P3P4-P6P7-P9P10-P12

LTC491CS#PBF

Mfr. #:
Buy LTC491CS#PBF
Manufacturer:
Analog Devices Inc.
Description:
RS-422/RS-485 Interface IC Low Power RS485 Tx/Rx
Lifecycle:
New from this manufacturer.
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