GENERAL DESCRIPTION
The ADM2491E is an isolated data transceiver with ±8 kV ESD protection and is suitable for high speed, half- or full-duplex communication on multipoint transmission lines. For half-
duplex operation, the transmitter outputs and the receiver
inputs share the same transmission line. Transmitter output Pin Y is linked externally to receiver input Pin A, and transmit-
ter output Pin Z is linked to receiver input Pin B. The ADM2491E is designed for balanced transmission lines
and complies with ANSI TIA/EIA RS-485-A-1998 and ISO
8482: 1987(E). The device employs Analog Devices, Inc.,
iCoupler® technology to combine a 3-channel isolator, a three-
state differential line driver, and a differential input receiver into
a single package.
The differential transmitter outputs and receiver inputs feature
electrostatic discharge circuitry that provides protection to ±8 kV using the human body model (HBM). The logic side of the device can be powered with either a 5 V or a 3.3 V supply,
whereas the bus side requires an isolated 5 V supply.
The device has current-limiting and thermal shutdown features
to protect against output short circuits and situations in which
bus contention could cause excessive power dissipation. The ADM2491E is available in a wide body, 16-lead SOIC package
and operates over the −40°C to +85°C temperature range.

FEATURES Isolated, RS-485/RS-422 transceiver, configurable as half- or
full-duplex ±8 kV ESD protection on RS-485 input/output pins
16 Mbps data rate
Complies with ANSI TIA/EIA RS-485-A-1998 and ISO 8482: 1987(E)
Suitable for 5 V or 3.3 V operation (VDD1)
High common-mode transient immunity: >25 kV/μs
Receiver has open-circuit, fail-safe design
32 nodes on the bus Thermal shutdown protection Safety and regulatory approvals UL recognition: 5000 V rms isolation voltage for 1 minute, per UL 1577
VDE certificate of conformity DIN V VDE V 0884-10 (VDE V 0884-10): 2006-12
Reinforced insulation, VIORM = 849 V peak Operating temperature range: −40°C to +85°C
Wide body, 16-lead SOIC package

APPLICATIONS
Isolated RS-485/RS-422 interfaces
Industrial field networks INTERBUS
Multipoint data transmission systems