bus transmission lines. It is designed for balanced transmis-
sion lines. It meets TIA/EIA RS485 and ISO 8482:1987(E).
鈩?/div>
differential
line driver and differential input receiver, both of which oper-
ate from a single 5.0V power supply. The driver and receiver
have an active high and active low enable, respectively, that
can be externally connected to function as a direction con-
trol. The driver and receiver differential inputs are internally
connected to form differential input/output (I/O) bus ports
that are designed to offer minimum loading to bus whenever
the driver is disabled or when V
CC
= 0V. These ports feature
wide positive and negative common mode voltage ranges,
making the device suitable for multipoint applications in
noisy environments. The LMS75LBC176 is available in a
8-Pin SOIC package. It is a drop-in socket replacement to
TI鈥檚 SN75LBC176.
Features
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Bidirectional transceiver
Meet ANSI standard RS-485
Low skew, 6ns
Low supply current, 8mA (max)
Wide input and output voltage range
High output drive capacity
鹵
60mA
Thermal shutdown protection
Open circuit fail-safe for receiver
Receiver input sensitivity
鹵
200mV
Receiver input hysteresis 10mV (min.)
Single supply voltage operation, 5V
Glitch free power-up and power-down operation
Pin and functional compatible with TI鈥檚 SN75LBC176
8-Pin SOIC
Applications
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Network hubs, bridges, and routers
Point of sales equipment (ATM, barcode readers,鈥?
Industrial programmable logic controllers
High speed parallel and serial applications
Multipoint applications with noisy environment
Typical Application
20047901
A typical multipoint application is shown in the above figure. Terminating resistors, RT, are typically required but only located at the two ends of the cable.
Pull up and pull down resistors maybe required at the end of the bus to provide failsafe biasing. The biasing resistors provide a bias to the cable when all
drivers are in TRI-STATE, See National Application Note, AN-847 for further information.
漏 2003 National Semiconductor Corporation
DS200479
www.national.com
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