LTC1487_15 Datasheet, PDF (1/8 Pages) Linear Technology – Ultra-Low Power RS485 with Low EMI, Shutdown and High Input Impedance

LTC1487
Ultra-Low Power RS485
with Low EMI, Shutdown
and High Input Impedance
FEATURES
s _{High Input Impedance: Up to 256 Transceivers}
on the Bus
s _{Low Power: ICC = 120µA Max with Driver Disabled}
s _{ICC = 200µA Max with Driver Enabled, No Load}
s _{1µA Quiescent Current in Shutdown Mode}
s _{Controlled Slew Rate Driver for Reduced EMI}
s _{Single 5V Supply}
s _{ESD Protection to ±10kV On Receiver Inputs and}
Driver outputs
s _{– 7V to 12V Common-Mode Range Permits ±7V}
Ground Difference Between Devices on the Data Line
s _{Thermal Shutdown Protection}
s _{Power Up/Down Glitch-Free Driver Outputs Permit}
Live Insertion or Removal of Transceiver
s _{Driver Maintains High Impedance in Three-State}
or with the Power Off
s _{Pin Compatible with the LTC485}
APPLICATI S
s _{Battery-Powered RS485/RS422 Applications}
s _{Low Power RS485/RS422 Transceiver}
s _{Level Translator}
DESCRIPTIO
The LTC^®1487 is an ultra-low power differential line trans-
ceiver designed with high impedance inputs allowing up to
256 transceivers to share a single bus. It meets the
requirements of RS485 and RS422. The LTC1487 features
output drivers with controlled slew rate, decreasing the
EMI radiated from the RS485 lines, and improving signal
fidelity with misterminated lines. The CMOS design offers
significant power savings without sacrificing ruggedness
against overload or ESD damage. Typical quiescent cur-
rent is only 80µA while operating and 1µA in shutdown.
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. I/O pins are protected against multiple
ESD strikes of over ±10kV using the Human Body Model.
The LTC1487 is fully specified over the commercial tem-
perature range and is available in 8-pin DIP and SO
packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATI
LTC1487
LTC1487
RO ¹ R
RE ²
2000 FEET OF TWISTED-PAIR WIRE
R ¹ RO
2 _RE
DI
DE ³
7
7
3 _DE
DI ⁴ D
120Ω
6
120Ω
6
D ⁴ DI
A
B
330Ω
4.7nF
RO
EQUIVALENT LOAD OF 256
LTC1487 TRANSCEIVERS
LTC1487 • TA01
LTC1487 • TA02
sn1487 1487fs
1