LTC1482 Datasheet, PDF (1/16 Pages) Linear Technology – Low Power RS485 Transceiver with Carrier Detect and Receiver Fail-Safe

FEATURES
s _{No Damage or Latchup to ±15kV (Human Body}
Model), IEC1000-4-2 Level 4 (±8kV) Contact and
Level 3 (±8kV) Air Discharge
s _{Active Low Carrier Detect Output}
s _{Guaranteed High Receiver Output State for}
Floating, Shorted or Terminated Inputs with
No Signal Present
s _{Drives Low Cost Residential Telephone Wires}
s _{Low Power: ICC = 700µA Max with Driver Disabled}
s _{ICC = 900µA Max in Driver Mode Without Load}
s _{20µA Max Quiescent Current in Shutdown Mode}
s _{Single 5V Supply}
s _{– 7V to 12V Common Mode Range Permits ±7V}
Ground Difference Between Devices on the Data Line
s _{Maximum Data Rate of 4Mbps}
s _{Power Up/Down Glitch-Free Driver Outputs}
s _{Up to 32 Transceivers on the Bus}
s _{Available in 8-Lead MSOP, PDIP and SO Packages}
U
APPLICATIO S
s _{Battery-Powered RS485/RS422 Applications}
s _{Low Power RS485/RS422 Transceiver}
s _{Level Translator}
, LTC and LT are registered trademarks of Linear Technology Corporation.
LTC1482
Low Power RS485 Transceiver
with Carrier Detect and
Receiver Fail-Safe
DESCRIPTIO
The LTC^®1482 is a low power RS485 compatible trans-
ceiver that offers an active low carrier detect output. The
open-drain carrier detect pin allows several transceivers
to share the same carrier detect line and can be used to
detect the insertion or removal of a driven RS485/RS422
cable.
Enhanced ESD protection allows the LTC1482 to with-
stand ±15kV (human body model), IEC-1000-4-2 level 4
(±8kV) contact and level 3 (±8kV) air discharge ESD
without latchup or damage.
The LTC1482 receiver stays alive at all times except in
shutdown. The supply current is a maximum of 700µA
and 900µA when the driver is disabled and enabled
respectively. In shutdown, the quiescent current of the
LTC1482 drops to a maximum of 20µA.
When the driver is disabled or the LTC1482 is in shut-
down, the driver outputs are three-stated and remain in
a high impedance state over the RS485 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 LTC1482 is fully specified over the commercial and
industrial temperature ranges and is available in 8-lead
MSOP, PDIP and SO packages.
TYPICAL APPLICATIO
RO1
CD1
DE1
DI1/SHDN1
RS485 Interface
LTC1482
R
D
V_CC1
B1
A1
120Ω
GND1
V_CC2
B2
120Ω _A2
GND2
LTC1482
R
D
RO2
CD2
DE2
DI2/SHDN2
1482 TA01
Carrier Detect Output (2000 Foot STP Cable)
DE1
A2
B2
CD2
DE1 ↑↓
DE2 = 0
1k PULL-UP AT CD
Dl1 = V_CC
Dl2 = V_CC
1482 TA01a
1