FEATURES
FUNCTIONAL BLOCK DIAGRAMS
VCC
ADM4850/ADM4851/
ADM4852/ADM4853
RO
A
RE
B
DE
D
DI
GND
Figure 1. ADM4850/ADM4851/ADM4852/ADM4853 Functional Block Diagram
VCC
ADM4854/ADM4855/
ADM4856/ADM4857
A
RO
R
B
APPLICATIONS
Z
DI
D
Y
Low power RS-485 applications
EMI sensitive systems
DTE to DCE interfaces
Industrial control
Packet switching
Local area networks
Level translators
GND
Figure 2. ADM4854/ADM4855/ADM4856/ADM4857 Functional Block Diagram
GENERAL DESCRIPTION
The ADM4850/ADM4851/ADM4852/ADM4853/ADM4854/
ADM4855/ADM4856/ADM4857 are differential line transceivers
suitable for high speed, half-duplex and full duplex data
communication on multipoint bus transmission lines. They
are designed for balanced data transmission and comply with
EIA Standards RS-485 and RS-422. The ADM4850/ADM4851/
ADM4852/ADM4853 are half-duplex transceivers that share
differential lines and have separate enable inputs for the driver
and receiver. The full duplex ADM4854/ADM4855/ADM4856/
ADM4857 transceivers have dedicated differential line driver
outputs and receiver inputs.
The devices have a 1/8-unit load receiver input impedance,
which allows up to 256 transceivers on one bus. Because only one
driver must be enabled at any time, the output of a disabled or
powered down driver is three-stated to avoid overloading the bus.
The receiver inputs have a true fail-safe feature, which ensures a
logic high output level when the inputs are open or shorted.
Rev. F
R
04931-001
Electronics industries alliance (EIA) RS-485/RS-422 compliant
Data rate options
ADM4850/ADM4854: 115 kbps
ADM4851/ADM4855: 500 kbps
ADM4852/ADM4856: 2.5 Mbps
ADM4853/ADM4857: 10 Mbps
Half-duplex and full duplex options
Reduced slew rates for low electromagnetic interference (EMI)
True fail-safe receiver inputs
5 µA (maximum) supply current in shutdown mode
Up to 256 transceivers on one bus
Outputs high-Z when disabled or powered off
−7 V to +12 V bus common-mode range
Thermal shutdown and short-circuit protection
Pin-compatible with the MAX308x
Specified over the −40°C to +85°C temperature range
Available in 8-lead SOIC, 8-lead LFCSP, and 8-lead MSOP
Qualified for automotive applications
04931-028
Data Sheet
5 V, Slew Rate Limited, Half-Duplex and
Full Duplex RS-485/RS-422 Transceivers
ADM4850 to ADM4857
This guarantees that the receiver outputs are in a known state
before communication begins and when communication ends.
The driver outputs are slew rate limited to reduce EMI and data
errors caused by reflections from improperly terminated buses.
Excessive power dissipation caused by bus contention or by
output shorting is prevented with a thermal shutdown circuit.
The devices are fully specified over the commercial and industrial
temperature ranges and are available in 8-lead SOIC (ADM4850
through ADM4857), 8-lead LFCSP (ADM4850/ADM4852/
ADM4853), and 8-lead MSOP (ADM4850 only) packages.
Table 1. Selection Table
Device No.
ADM4850
ADM4851
ADM4852
ADM4853
ADM4854
ADM4855
ADM4856
ADM4857
Half-Duplex/Full Duplex
Half
Half
Half
Half
Full
Full
Full
Full
Data Rate
115 kbps
500 kbps
2.5 Mbps
10 Mbps
115 kbps
500 kbps
2.5 Mbps
10 Mbps
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