UM3487E Datasheet, PDF (1/14 Pages) Union Semiconductor, Inc. – ±15kV ESD-Protected, Fail-Safe, Hot-Swappable Auto Polarity Reversal RS-485 Transceivers

UM3487E
±15kV ESD-Protected, Fail-Safe, Hot-Swappable
Auto Polarity Reversal RS-485 Transceivers
UM3487E SOP8/DIP8
General Description
The UM3487E series are +3.3V powered ±15kV ESD protected, fail-safe, hot-swappable, auto
polarity reversal RS-485 transceivers. The device includes fail-safe circuitry, which guarantees a
logic-high receiver output when the receiver inputs are open, shorted or idle. This means that the
receiver output will be logic high if all transmitters on a terminated bus are disabled (high
impedance). The UM3487E features reduced slew-rate driver that minimizes EMI and reduces
reflections caused by improperly terminated cables, allowing error-free data transmission up to
500kbps. All transmitter outputs and receiver inputs are protected to ±15kV using the Human
Body Model and IEC61000-4-2, Air-Gap Discharge.
The UM3487E includes cable auto-invert functions that reverse the polarity of the RS485 bus pins
in case the cable is misconnected. Receiver’s full fail-safe features are maintained even when the
receiver polarity has been reversed.
The transceivers typically draw 300μA of supply current when unloaded, or when fully loaded
with the drivers disabled. The device has a 1/8-unit-load receiver input impedance that allows up
to 256 transceivers on the bus and is intended for half-duplex communications.
Applications
Features
 Smart Meters/Automated Meter
 Automatic Polarity Reversal RS-485
Reading Systems
Transceivers
 Industrial-Control Local Area
 I/O logic compatible with +5V, +3.3V &
Networks
+1.8V logic
 PROFIBUS® and Other RS-485 Based  ESD Protection for RS-485 I/O Pins
Field Bus Networks
±15kV—IEC61000-4-2, Air-Gap Discharge
 Building Lighting and Environmental
±8kV—IEC61000-4-2, Contact Discharge
Control Systems
 True Fail-Safe Receiver
 High Node Count RS-485 Systems
 Enhanced Slew-Rate Limiting
 Transceivers for EMI-Sensitive
 –7V to +12V Common-Mode Input Voltage
Applications
Range
 Allows up to 256 Transceivers on the Bus
 Thermal Shutdown
 Current-Limiting for Driver Overload
Protection
Pin Configurations
RO 1
RE 2
DE 3
DI 4
8 VCC
7 L1
6 L2
5 GND
Top View
XXXXXX
XXXX
XX
Ordering Information
Part Number
Marking Code
UM3487EESA
UM3487EESA
UM3487EEPA
UM3487EEPA
Operating Temperature
-40°C to +85°C
-40°C to +85°C
Package Type
SOP8
DIP8
________________________________________________________________________
http://www.union-ic.com Rev.02 Jan.2014
1/14