Features
 Polarity Free for RS485 bus pins
 Integrated TVS Protection for Bus Terminals :
±15 kV IEC 61000-4-2, Contact Discharge
±20 kV IEC 61000-4-2, Air-Gap Discharge
 HBM ±8kV ESD Protection for all pins
 MM ±800V ESD Protection for all pins
 Meet the Requirements of the EIA/TIA-485
Standards with 5V Power Supply
 True Fail-Safe Receiver While Maintaining
EIA/TIA-485 Compatibility
 Data Rate up to 10Mbps
 Hot-Swap Glitch free Protection on Control
Inputs
 Up to 256 Transceivers on the Bus
Applications
 Energy Meter Networks
 Motor Control
 Industrial Control
 Telecommunications Equipment
 Security System
 Building Automation Networks
Description
The AZRS485N is a Polarity-Free half-duplex
RS485 transceiver IC with ±15kV IEC 61000-4-2
contact discharge protection. This device is fully
compliant with the EIA/TIA-485 standard with 5V
power supply. The Parity-Free AZRS485N can
automatically detect the polarity for A and B pins
when pull-high for A and “pull-low” for B have
been designed on the RS485 bus. The polarity
detection function will be enabled when the
AZRS485N has been power up to 5V.
The detection function is real-time monitored the
bus polarity without any data flow on the RS485
bus. AZRS485N is slave-type RS485 to feature
the Polarity Free function, which can not design
the pull-up and pull-down resistor on the slave
device.
AZRS485N features an advanced fail-safe
receiver, which combined the true fail-safe and
Polarity Free function to guarantees the output of
the receiver to be logic high when the differential
inputs (bus pins, A and B) of the receiver are
open, short, idle, and even inverting connection.
AZRS485N features a hot-swap glitch-free
function which guarantees outputs of both the
transmitter and the receiver in a high impedance
state so as to prevent short current event during
the power up period. AZRS485N has the thermal
shutdown and the current limited function in the
transmitter to protect the device from damage by
system fault conditions during normal operating
condition. AZRS485N is designed 1/8 unit load
with minimum 96kohm of input impedance, which
can connect 256 devices on a bus at least.