ADM485ARMZ-REEL7 ADI Chips 5V Low Power EIA RS-485 Transceiver Single Supply

ADI chips ADM485ARMZ-REEL7 5 V Low Power EIA RS-485 Transceive Single 5 V supply

GENERAL DESCRIPTION 
The ADM485 is a differential line transceiver suitable for high 
speed bidirectional data communication on multipoint bus 
transmission lines. It is designed for balanced data transmission 
and complies with EIA standards RS-485 and RS-422. The part 
contains a differential line driver and a differential line receiver. 
Both the driver and the receiver can be enabled independently. 
When disabled, the outputs are three-stated. 
The ADM485 operates from a single 5 V power supply. 
Excessive power dissipation caused by bus contention or by 
output shorting is prevented by a thermal shutdown circuit. If 
during fault conditions, a significant temperature increase is 
detected in the internal driver circuitry, this feature forces the 
driver output into a high impedance state. 
Up to 32 transceivers can be connected simultaneously on a 
bus, but only one driver should be enabled at any time. It is 
important, therefore, that the remaining disabled drivers do not 
load the bus. To ensure this, the ADM485 driver features high 
output impedance when disabled and when powered down, 
which minimizes the loading effect when the transceiver is not 
being used. The high impedance driver output is maintained 
over the common-mode voltage range of −7 V to +12 V.
The receiver contains a fail-safe feature that results in a logic 
high output state if the inputs are unconnected (floating). 
The ADM485 is fabricated on BiCMOS, an advanced mixed 
technology process combining low power CMOS with fast 
switching bipolar technology. All inputs and outputs contain 
protection against ESD; all driver outputs feature high source 
and sink current capability. An epitaxial layer is used to guard 
against latch-up. 
The ADM485 features extremely fast switching speeds. Minimal 
driver propagation delays permit transmission at data rates up 
to 5 Mbps while low skew minimizes EMI interference. 
The part is fully specified over the commercial and industrial 
temperature range and is available in 8-lead PDIP, 8-lead SOIC, 
and small footprint, 8-lead MSOP packages.