ADM2682EBRIZ datasheet(18/20 Pages) AD

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ADM2682E/ADM2687E

Preliminary Technical Data

Rev. PrE | Page 18 of 20

voltages listed in Table 9 can be applied while maintaining the

50-year minimum lifetime, provided the voltage conforms to either

the unipolar ac or dc voltage cases. Any crossinsulation voltage

waveform that does not conform to Figure 37 or Figure 38 should

be treated as a bipolar ac waveform, and its peak voltage should

be limited to the 50-year lifetime voltage value listed in Table 9.

Figure 36. Bipolar AC Waveform

Figure 37. DC Waveform

Figure 38. Unipolar AC Waveform

TYPICAL APPLICATIONS

An example application of the ADM2682E/ADM2687E for a

full-duplex RS-485 node is shown in the circuit diagram of

Figure 39. Refer to the section PCB Layout for the

recommended placement of the capacitors shown in this circuit

diagram. Note that resistors RT are only included at the nodes

on either end of the bus and depend on the network

configuration.

Figure 40 and Figure 41 show typical applications of the

ADM2682E/ ADM2687E in half duplex and full duplex RS-485

network configurations. Up to 256 transceivers can be connected to

the RS-485 bus. To minimize reflections, terminate the line at the

receiving end in its characteristic impedance, and keep stub

lengths off the main line as short as possible. For half-duplex

operation, this means that both ends of the line must be

terminated because either end can be the receiving end.

Figure 39. Example Circuit Diagram Using the ADM2682E/ADM2687E

RATED PEAK VOLTAGE

NOTES

1. THE VOLTAGE IS SHOWN AS SINUSODIAL FOR ILLUSTRATION

PURPOSES ONLY. IT IS MEANT TO REPRESENT ANY VOLTAGE

WAVEFORM VARYING BETWEEN 0 AND SOME LIMITING VALUE.

THE LIMITING VALUE CAN BE POSITIVE OR NEGATIVE, BUT THE

VOLTAGE CANNOT CROSS 0V.

ADM2682E/ADM2687E

TxD

RxD

ISOLATION

BARRIER

TRANSCEIVER

GND1

GND2

ENCODE

DECODE

OSCILLATOR

RECTIFIER

REGULATOR

VISOOUT

VCC

VISOIN

MICROCONTROLLER

AND UART

3.3V/5V POWER

SUPPLY

100nF

10µF

100nF

10nF

100nF

10µF

100nF

10nF

DIGITAL ISOLATION iCoupler

isoPower DC-TO-DC CONVERTER

ADM2682EBRIZ Datasheet(PDF) 18 Page - Analog Devices

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