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
Reading Systems
Industrial-Control Local Area
Networks
PROFIBUS® and Other RS-485 Based
Field Bus Networks
Building Lighting and Environmental
Control Systems
High Node Count RS-485 Systems
Transceivers for EMI-Sensitive
Applications
Automatic Polarity Reversal RS-485
Transceivers
I/O logic compatible with +5V, +3.3V &
+1.8V logic
ESD Protection for RS-485 I/O Pins
±15kV—IEC61000-4-2, Air-Gap Discharge
±8kV—IEC61000-4-2, Contact Discharge
True Fail-Safe Receiver
Enhanced Slew-Rate Limiting
–7V to +12V Common-Mode Input Voltage
Range
Allows up to 256 Transceivers on the Bus
Thermal Shutdown
Current-Limiting for Driver Overload
Protection
Pin Configurations
Top View
RO
RE
DE
DI
1
2
3
4
8
7
6
5
VCC
L1
XXXXXX
XXXX
XX
L2
GND
Ordering Information
Part Number
Marking Code
UM3487EESA
UM3487EEPA
Operating Temperature
-40°C to +85°C
Package Type
SOP8
UM3487EESA
UM3487EEPA
-40°C to +85°C
DIP8
________________________________________________________________________
http://www.union-ic.com Rev.02 Jan.2014 1/14