5 V, ±15 kV ESD Protected

Half-Duplex, RS-485/RS-422 Transceivers

ADM485E/ADM487E/ADM1487E

Rev. 0

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FEATURES

TIA/EIA RS-485-/RS-422-compliant

ESD protection on RS-485 I/O pins

±15 kV human body model

Data rates

ADM487E: 250 kbps

ADM485E/ADM1487E: 2.5 Mbps

Half-duplex options

Reduced slew rates for low EMI

−7 V to +12 V common-mode input range

Thermal shutdown and short-circuit protection

8-lead SOIC packages

APPLICATIONS

Energy/power metering

Lighting systems

Industrial control

Telecommunications

Security systems

Instrumentation

FUNCTIONAL BLOCK DIAGRAM

GND

ADM485E/

ADM487E/

ADM1487E

06356-001

Figure 1.

GENERAL DESCRIPTION

The ADM485E/ADM487E/ADM1487E are 5 V, low power

data transceivers with ±15 kV ESD protection suitable for half-

duplex communication on multipoint bus transmission lines.

They are designed for balanced data transmission and comply

with Telecommunication Industry Association/Electronics Indus-

tries Association (TIA/EIA) standards RS-485 and RS-422. The

ADM487E and ADM1487E have a 1/4 unit load receiver input

impedance that allows up to 128 transceivers on a bus, whereas

the ADM485E allows up to 32 transceivers on a bus. Because

only one driver is enabled at any time, the output of a disabled or

power-down driver is three-stated to avoid overloading the bus.

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 output

shorting is prevented with a thermal shutdown circuit.

The parts are fully specified over the industrial temperature

ranges and are available in 8-lead SOIC packages.

Table 1. Selection Table

Part

Number

Half-/Full-

Duplex

Guaranteed

Data Rate

(Mbps)

Slew Rate

Limited

Low Power

Shutdown

Driver/Receiver

Enable

Quiescent

Current (μA)

Number of

Nodes on Bus

Count

ADM485E Half 2.5 No No Yes 300 32 8

ADM487E Half 0.25 Yes Yes Yes 120 128 8

ADM1487E Half 2.5 No No Yes 230 128 8

ADM485E/ADM487E/ADM1487E

Rev. 0 | Page 2 of 16

TABLE OF CONTENTS

Features .............................................................................................. 1

Applications....................................................................................... 1

Functional Block Diagram .............................................................. 1

General Description......................................................................... 1

Revision History ............................................................................... 2

Specifications..................................................................................... 3

Timing Specifications .................................................................. 4

Absolute Maximum Ratings............................................................ 6

ESD Caution.................................................................................. 6

Pin Configuration and Function Descriptions............................. 7

Typical Performance Characteristics ..............................................8

Test Circuits and Switching Characteristics................................ 11

Theory of Operation ...................................................................... 13

Circuit Description .................................................................... 13

Applications Information.............................................................. 15

Differential Data Transmission ................................................ 15

Cable and Data Rate................................................................... 15

Outline Dimensions ....................................................................... 16

Ordering Guide .......................................................................... 16

REVISION HISTORY

1/07—Revision 0: Initial Version

ADM485E/ADM487E/ADM1487E

Rev. 0 | Page 3 of 16

SPECIFICATIONS

= 5 V ± 5%, T

= T

MIN

to T

MAX

, unless otherwise noted.

Table 2. ADM485E/ADM487E/ADM1487E

Parameter Symbol Min Typ Max Unit Test Conditions/Comments

DRIVER

Differential Outputs

Differential Output Voltage (no Load) V

OD1

5 V

OD2

2 V R

= 50 Ω (RS-422) Differential Output Voltage (with Load)

1.5 5 V R

= 27 Ω (RS-485) (see Figure 18)

Δ |V

| for Complementary Output

States

0.2 V R

= 27 Ω or 50 Ω (see Figure 18)

Common-Mode Output Voltage V

3 V R

= 27 Ω or 50 Ω (see Figure 18)

Δ |V

| for Complementary Output

States

0.2 V R

= 27 Ω or 50 Ω (see Figure 18)

Logic Inputs

Input High Voltage V

2.0 V

DE, DI, RE

Input Low Voltage V

0.8 V

DE, DI, RE

Logic Input Current I

IN1

±2 μA

DE, DI, RE

RECEIVER

IN2

1.0 mA DE = 0 V, V

= 12 V

−0.8 mA V

= 0 V or +5.25 V, V

= −7 V (ADM485E)

0.25 mA DE = 0 V, V

= 12 V

Input Current (A, B)

−0.2 mA

= 0 V or +5.25 V, V

= −7 V

(ADM487E/ADM1487E)

Differential Inputs

Differential Input Threshold Voltage V

−0.2 +0.2 V −7 V < V

< +12 V

Input Hysteresis ΔV

70 mV V

= 0 V

Receiver Output Logic

Output Voltage High V

3.5 V I

OUT

= −4 mA, V

= +200 mV

Output Voltage Low V

0.4 V I

OUT

= +4 mA, V

= −200 mV

Three-State Output Leakage Current I

OZR

±1 μA 0.4 V < V

< 2.4 V

12 kΩ −7 V < V

< +12 V (ADM485E) Receiver Input Resistance

48 kΩ −7 V< V

< +12 V (ADM487E/ADM1487E)

POWER SUPPLY

500 900 μA

= 0 V or V

, DE = V

(ADM485E)

300 500 μA

= 0 V or V

, DE = 0 V (ADM485E)

300 500 μA

= 0 V or V

, DE = V

(ADM1487E)

230 400 μA

= 0 V or V

, DE = 0 V (ADM1487E)

250 400 μA

= 0 V or V

, DE = V

(ADM487E)

No Load Supply Current

120 250 μA

= 0 V, DE = 0 V (ADM487E)

Supply Current in Shutdown I

SHDN

0.5 10 μA

DE = 0 V, RE

= V

(ADM487E)

Driver Short-Circuit Current, V

High I

OSD1

35 250 mA −7 V ≤ V

≤ +12 V, applies to peak current

Driver Short-Circuit Current, V

Low I

OSD2

35 250 −7 V ≤ V

≤ +12 V, applies to peak current

Receiver Short-Circuit Current I

OSR

7 95 mA 0 V ≤ V

≤ V

ESD PROTECTION

A, B Pins ±15 kV Human body model

Part #	ADM487EARZ
Description	IC TXRX HALF DUP RS485/422 8SOIC
Category	IC
Availability	Out of Stock
Qty	0

ADM487EARZ

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