Analog Devices ADM3485E Datasheet

ESD Protected, EMC Compliant, 3.3 V,

a

FEATURES
Operates with +3.3 V Supply
ESD Protection: 8 kV Meets IEC1000-4-2
EFT Protection: 2 kV Meets IEC1000-4-4
EIA RS-422 and RS-485 Compliant Over Full CM Range
19 k Input Impedance
Up to 50 Transceivers on Bus
20 Mbps Data Rate
Short Circuit Protection
Specified Over Full Temperature Range
Thermal Shutdown
Interoperable with 5 V Logic
1 mA Supply Current
2 nA Shutdown Current
8 ns Skew

APPLICATIONS
Telecommunications
DTE-DCE Interface
Packet Switching
Local Area Networks
Data Concentration
Data Multiplexers
Integrated Services Digital Network (ISDN)
AppleTalk
Industrial Controls

20 Mbps, EIA RS-485 Transceiver

ADM3485E

FUNCTIONAL BLOCK DIAGRAM

ADM3485E

RO

RE

DE

DI

R

B

A

D

GENERAL DESCRIPTION

The ADM3485E is a low power differential line transceiver
designed to operate using a single +3.3 V power supply. Low
power consumption makes it ideal for power sensitive applica­tions. It is suitable for communication on multipoint bus trans­mission lines. Internal protection against electrostatic discharge
(ESD) and electrical fast transient (EFT) allows operation in
electrically harsh environments.

It is intended for balanced data transmission and complies with
both EIA Standards RS-485 and RS-422. It contains a differen­tial line driver and a differential line receiver, and is suitable for
half duplex data transfer.

The input impedance is 19 kΩ allowing up to 50 transceivers to
be connected on the bus.

REV. A

Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.

Excessive power dissipation caused by bus contention or by
output shorting is prevented by a thermal shutdown circuit.
This feature forces the driver output into a high impedance
state if, during fault conditions, a significant temperature
increase is detected in the internal driver circuitry.

The receiver contains a fail-safe feature that results in a
logic high output state if the inputs are unconnected
(floating).

The ADM3485E is fabricated on BiCMOS, an advanced
mixed technology process combining low power CMOS
with fast switching bipolar technology.

The ADM3485E is fully specified over the industrial tem­perature range and is available in 8-lead DIP and SOIC
packages.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] World Wide Web Site: http://www.analog.com
Fax: [phone] © Analog Devices, Inc., 2000

ADM3485E–SPECIFICATIONS

(VCC = +3.3 V  0.3 V. All specifications T

MIN

to T

unless otherwise noted.)

MAX

Parameter Min Typ Max Units Test Conditions/Comments

DRIVER

Differential Output Voltage, V

∆|V

| for Complementary Output States 0.2 V R = 54 Ω or 100 Ω, Figure 1

OD

Common-Mode Output Voltage V
∆|V

| for Complementary Output States 0.2 V R = 54 Ω or 100 Ω, Figure 1

OC

OD

OC

CMOS Input Logic Threshold Low, V
CMOS Input Logic Threshold High, V

2.0 V RL = 100 Ω, Figure 1, VCC > 3.1 V

1.5 V R

1.5 V R

= 54 Ω, Figure 1

L

= 60 Ω, Figure 2, –7 V < V

L

3 V R = 54 Ω or 100 Ω, Figure 1

INL

2.0 V

INH

0.8 V

< +12 V

TST

Logic Input Current (DE, DI, RE) ± 1.0 µA
Output Short Circuit Current ± 250 mA VO = –7 V or +12 V

RECEIVER

Differential Input Threshold Voltage, V
Input Voltage Hysteresis, ∆V

TH

Input Resistance 12 19 kΩ –7 V < V
Input Current (A, B) +1 mA V

–0.2 +0.2 V –7 V < VCM < +12 V

TH

50 mV VCM = 0 V

= +12 V

IN

–0.8 mA V

= –7 V

IN

< +12 V

CM

Logic Enable Input Current (RE) ± 1 µA
Output Voltage Low, V
Output Voltage High, V

OL

OH

VCC – 0.4 V V I
Short Circuit Output Current ± 60 mA V
Three-State Output Leakage Current ± 1.0 µAV

0.4 V I

= +2.5 mA

OUT

= –1.5 mA

OUT

= GND or V

OUT

= 3.6 V, 0 V < V

CC

CC

OUT

< V

CC

POWER SUPPLY CURRENT

I

CC

1 1.2 mA DE = V

Outputs Unloaded,

, RE = 0 V

CC

1 1.2 mA DE = 0 V, RE = 0 V

Supply Current in Shutdown 0.002 1 µA DE = 0 V, RE = V

CC

ESD/EFT IMMUNITY

ESD Protection ± 8 kV IEC1000-4-2 A, B Pins Contact Discharge
EFT Protection ± 2 kV IEC1000-4-4, A, B Pins

Specifications subject to change without notice.

–2–

REV. A

ADM3485E

TIMING SPECIFICATIONS

(VCC = +3.3 V, TA = +25C)

Parameter Min Typ Max Units Test Conditions/ Comments

DRIVER

Differential Output Delay T

DD

Differential Output Transition Time 1 8 15 ns R
Propagation Delay Input to Output T
Driver O/P to O/P T

SKEW

PLH

, T

PHL

135nsR

72235nsR

8nsR

= 60 Ω, CL1 = CL2 = 15 pF, Figure 3

L

= 60 Ω, CL1 = CL2 = 15 pF, Figure 3

L

= 27 Ω, CL1 = CL2 = 15 pF, Figure 7

L

= 54 Ω, CL1 = CL2 = 15 pF, Figure 3

L

ENABLE/DISABLE

Driver Enable to Output Valid 45 90 ns R
Driver Disable Timing 40 80 ns R

= 110 Ω, CL = 50 pF, Figure 2

L

= 110 Ω, CL = 50 pF, Figure 2

L

Driver Enable from Shutdown 650 110 ns RL = 110 Ω, CL = 15 pF, Figure 2

RECEIVER

Time to Shutdown 80 190 300 ns
Propagation Delay Input to Output T
Skew T
Receiver Enable T
Receiver Disable T

PLH–TPHL

EN

DEN

PLH

, T

PHL

25 65 90 ns CL = 15 pF, Figure 8

10 ns CL = 15 pF, Figure 8
25 50 ns CL = 15 pF, Figure 6
25 45 ns CL = 15 pF, Figure 6

Receiver Enable from Shutdown 500 ns CL = 15 pF, Figure 6

Specifications subject to change without notice.

TIMING SPECIFICATIONS

(VCC = +3.3 V  0.3 V, TA = T

MIN

to T

MAX

)

Parameter Min Typ Max Units Test Conditions/ Comments

DRIVER

Differential Output Delay T

DD

Differential Output Transition Time 2 8 15 ns R
Propagation Delay Input to Output T
Driver O/P to O/P T

SKEW

PLH

, T

PHL

170nsR

72270nsR

= 60 Ω, CL1 = CL2 = 15 pF, Figure 3

L

= 60 Ω, CL1 = CL2 = 15 pF, Figure 3

L

= 27 Ω, CL1 = CL2 = 15 pF, Figure 7

L

10 ns RL = 54 Ω, CL1 = CL2 = 15 pF, Figure 3

ENABLE/DISABLE

Driver Enable to Output Valid 45 110 ns R
Driver Disable Timing 40 110 ns R

= 110 Ω, CL = 50 pF, Figure 2

L

= 110 Ω, CL = 50 pF, Figure 2

L

Driver Enable from Shutdown 650 110 ns RL = 110 Ω, CL = 15 pF, Figure 2

RECEIVER

Time to Shutdown 50 190 500 ns
Propagation Delay Input to Output T
Skew T
Receiver Enable T
Receiver Disable T

PLH–TPHL

EN

DEN

PLH

, T

PHL

25 65 115 ns CL = 15 pF, Figure 8

20 ns CL = 15 pF, Figure 8

25 50 ns CL = 15 pF, Figure 6
25 50 ns CL = 15 pF, Figure 6

Receiver Enable from Shutdown 600 ns CL = 15 pF, Figure 6

Specifications subject to change without notice.

–3–REV. A

ADM3485E

ABSOLUTE MAXIMUM RATINGS*

(TA = +25°C unless otherwise noted)

VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7 V

Inputs

Driver Input (DI) . . . . . . . . . . . . . . . . –0.3 V to V

Control Inputs (DE, RE) . . . . . . . . . . –0.3 V to V

+ 0.3 V

CC

+ 0.3 V

CC

Receiver Inputs (A, B) . . . . . . . . . . . . . . . –7.5 V to +12.5 V

Outputs

Driver Outputs . . . . . . . . . . . . . . . . . . . . . –7.5 V to +12.5 V

Receiver Output . . . . . . . . . . . . . . . . . –0.5 V to V

+ 0.5 V

CC

Power Dissipation 8-Lead DIP . . . . . . . . . . . . . . . . . 800 mW

, Thermal Impedance . . . . . . . . . . . . . . . . . . . . 140°C/W

θ

JA

Power Dissipation 8-Lead SOIC . . . . . . . . . . . . . . . . 650 mW

, Thermal Impedance . . . . . . . . . . . . . . . . . . . . 115°C/W

θ

JA

Operating Temperature Range

Industrial (A Version) . . . . . . . . . . . . . . . . –40°C to +85°C

Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C

Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . . +300°C

Vapor Phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . . +215°C

Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . +220°C

ESD Rating: Air (Human Body Model, All Pins) . . . . . >4 kV

ESD Rating: IEC1000-4-2 Contact (A, B Pins) . . . . . . >8 kV

EFT Rating: IEC1000-4-4 (A, B Pins) . . . . . . . . . . . . . >2 kV

*Stresses above those listed under Absolute Maximum Ratings may cause perma-

nent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those listed in the operational sections
of this specification is not implied. Exposure to absolute maximum ratings for
extended periods of time may affect device reliability.

ORDERING GUIDE

Model Temperature Range Package Description Package Options

ADM3485EAN –40°C to +85°C Plastic DIP N-8
ADM3485EAR –40°C to +85°C Small Outline (SOIC) SO-8

PIN CONFIGURATION

DIP/SOIC

RO

RE

DE

DI

1

ADM3485E

2

3

TOP VIEW

(Not to Scale)

4

8

V

CC

7

B

6

A

5

GND

PIN FUNCTION DESCRIPTIONS

Mnemonic DIP/
Pin SOIC Function

RO 1 Receiver Output. High when A > B by 200 mV or low when A < B by 200 mV.
RE 2 Receiver Output Enable. With RE low, the receiver output RO is enabled. With RE high, the output goes

high impedance. If RE is high and DE low, the ADM3485E enters a shutdown state.

DE 3 Driver Output Enable. A high level enables the driver differential outputs, A and B. A low level places it in a

high impedance state.

DI 4 Driver Input. When the driver is enabled, a logic low on DI forces A low and B high, while a logic high on DI

forces A high and B low.
GND 5 Ground Connection, 0 V.
A 6 Noninverting Receiver Input A/Driver Output A.
B 7 Inverting Receiver Input B/Driver Output B.
V

CC

8 Power Supply, 3.3 V ± 0.3 V.

–4–

REV. A