Half-duplex,15-kV ESD, 1/4 UL Transceiver

The SN65LBC182 and SN75LBC182 are

differential data line transceivers with a high level of ESD protection in the

trade-standard footprint of the SN75176. They are designed for balanced transmission

lines and meet ANSI standard TIA/EIA-485-A and ISO 8482. The SN65LBC182 and

SN75LBC182 combine a 3-state, differential line driver and differential input line

receiver, both of which operate from a single 5-V power supply. The driver and

receiver have active-high and active-low enables, respectively, which can be

externally connected together to function as a direction control.

The driver

outputs and the receiver inputs connect internally to form a differential

input/output (I/O) bus port that is designed to offer minimum loading to the bus.

This port operates over a wide range of common-mode voltage, making the device

suitable for party-line applications. The device also includes additional features

for party-line data buses in electrically noisy environment applications such as

industrial process control or power inverters.

The SN75LBC182 and SN65LBC182 bus pins

also exhibit a high input resistance equivalent to one-fourth unit load allowing

connection of up to 128 similar devices on the bus. The high ESD tolerance protects

the device for cabled connections. (For an even higher level of protection, see the

SN65/75LBC184, literature number SLLS236.)

The differential driver design

incorporates slew-rate-controlled outputs sufficient to transmit data up to 250

kbps. Slew-rate control allows longer unterminated cable runs and longer stub

lengths from the main backbone than possible with uncontrolled voltage transitions.

The receiver design provides a fail-safe output of a high level when the inputs are

left floating (open circuit). Very low device supply current can be achieved by

disabling the driver and the receiver.

The SN65LBC182 is characterized for

operation from −40°C to 85°C, and the SN75LBC182 is characterized for operation from

0°C to 70°C.