LTC1686 Datasheet, PDF (1/12 Pages) Linear Technology – 52Mbps Precision Delay RS485 Fail-Safe Transceivers

LTC1686/LTC1687
52Mbps Precision Delay
RS485 Fail-Safe Transceivers
FEATURES
s _{Precision Propagation Delay Over Temperature:}
Receiver/Driver: 18.5ns ±3.5ns
s _{High Data Rate: 52Mbps}
s _{Low tPLH/tPHL Skew:}
Receiver/Driver: 500ps Typ
s _{–7V to 12V RS485 Input Common Mode Range}
s _{Guaranteed Fail-Safe Operation Over the Entire}
Common Mode Range
s _{High Input Resistance: ≥ 22k, Even When Unpowered}
s _{Short-Circuit Protected}
s _{Thermal Shutdown Protected}
s _{Driver Maintains High Impedance in Three-State or}
with Power Off
s _{Single 5V Supply}
s _{Pin Compatible with LTC490/LTC491}
s _{45dB CMRR at 26MHz}
U
APPLICATIONS
s _{High Speed RS485/RS422 Full Duplex Transceivers}
s _{Level Translator}
s _{Backplane Transceiver}
s _{STS-1/OC-1 Data Transceiver}
s _{Signal Repeaters}
DESCRIPTION
The LTC^®1686/LTC1687 are high speed, precision delay,
full-duplex RS485 transceivers that can operate at data
rates as high as 52Mbps. The devices also meet the
requirements of RS422.
A unique architecture provides very stable propagation
delays and low skew over a wide common mode and
ambient temperature range.
The driver and receiver feature three-state outputs, with
disabled driver outputs maintaining high impedance over
the entire common mode range. A short-circuit feature
detects shorted outputs and substantially reduces driver
output current. A similar feature also protects the receiver
output from short circuits. Thermal shutdown circuitry
protects from excessive power dissipation.
The receiver has a fail-safe feature that guarantees a high
output state when the inputs are shorted or are left floating.
The LTC1686/LTC1687 RS485 transceivers guarantee
receiver fail-safe operation over the entire common mode
range (– 7V to 12V). Receiver input resistance remains
≥ 22k when the device is unpowered or disabled.
The LTC1686/LTC1687 operate from a single 5V supply
and draw only 7mA of supply current.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATION
LTC1686
3
D
DRIVER
5
100Ω
6
100Ω
2
R
RECEIVER
8
100Ω
7
100Ω
400 FT OF CATEGORY 5 UTP
LTC1686
RECEIVER
10Mbps Data Pulse
400 Feet Category 5 UTP
2V/DIV
R
1V/DIV
CABLE DELAY
DRIVER INPUT
RECEIVER
INPUT
DRIVER
D
5V/DIV
RECEIVER
OUTPUT
LTC1686/87 • TA01
100ns/DIV
1686/87 TA02
1