ADM1486JN [ADI]

+5 V Low Power RS-485 PROFIBUS Transceiver; + 5V低功耗RS - 485收发器PROFIBUS


型号：	ADM1486JN
厂家：	ADI
描述：	+5 V Low Power RS-485 PROFIBUS Transceiver + 5V低功耗RS - 485收发器PROFIBUS
文件：	总8页 (文件大小：149K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

PRELIMINARY TECHNICAL DATA

+5 V Low Power

RS-485PROFIBUSTransceiver

Preliminary Technical Data

ADM1486

FEATURES

FUNCTIONAL BLOCK DIAGRAM

Meets & Exceeds EIA RS-485 & EIA RS-422 Standard

50 Mb/s Data Rate

Recommended for PROFIBUS Applications

2.1V Minimum Differential Output with 54⍀

Termination

Low Power 0.5mA I_CC

Thermal Shutdown & Short Circuit Protection

Zero Skew Driver & Receiver

Driver Propagation Delay: 8 ns

Receiver Propagation Delay: 12 ns

High Z Outputs with Drivers Disabled or Power Off

Superior Upgrade for SN65ALS1176

15kV HBM ESD Protection on I/O Pins A & B

Available in Standard 8-pin SOIC & Miniature 8-pin

Micro SOIC packages

GND

ADM1486

APPLICATIONS

Industrial Field Equipment

GENERAL DESCRIPTION

The ADM1486 is a differential line transceiver suitable

for high speed bidirectional data communication on

multipoint bus transmission lines. It is designed for

balanced data transmission, complies with EIA Standards

RS-485 and RS-422 and is recommended for PROFIBUS

applications. The part contains a differential line driver

and a differential line receiver. Both the driver and the

receiver may be enabled independently. When disabled or

with power off, the driver outputs are tristated.

This minimizes the loading effect when the transceiver is

not being utilized. The high impedance driver output is

maintained over the entire common-mode voltage range

from –7 V to +12 V.

The receiver contains a fail safe feature which results in a

logic high output state if the inputs are unconnected

(floating).

The ADM1486 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 epi-

taxial layer is used to guard against latch-up.

The ADM1486 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. 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 ADM1486 features extremely fast switching speeds.

Minimal driver propagation delays permit transmission at

data rates up to 50 Mbits/s while low skew minimizes

EMI interference.

Up to 50 transceivers may 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 ADM1486

driver features high output impedance when disabled and

also when powered down.

The part is fully specified over the commercial and indus-

trial temperature range and is available in an 8-lead

DIL/SOIC/µSOIC package.

REV Pr. B

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.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781/329-4700

Fax: 781/326-8703

World Wide Web Site: http://www.analog.com

PRELIMINARY TECHNICAL DATA

(V_CC= +5 V 5ꢀ% All sꢁeciꢂications T_MINto T_MAXunless otherwise noted%)

ADM1486–SPECIFICATIONS

Parameter

Min Typ Max

Unit Test Conditions/Comments

DRIVER

Differential Output Voltage, V_OD

5.0

0.2

150

0.8

µA

R = Infinity, Figure 1

V_CC= 5 V, R = 50 ⍀ (RS-422), Figure 1

2.0

2.1

R = 27 ⍀ (RS-485), Figure 1

V_TST= –7 V to +12 V, Figure 2

R = 27 ⍀ or 50 ⍀, Figure 1

R = 27 ⍀ or 50 ⍀

–7 V р V_Oр +12 V

V_OD3

⌬|V_OD| for Complementary Output States

Common-Mode Output Voltage V_OC

⌬|V_OD| for Complementary Output States

Output Short Circuit Current(V_OUT=High) 60

Output Short Circuit Current(V_OUT=Low) 60

CMOS Input Logic Threshold Low, V_INL

CMOS Input Logic Threshold High, V_INH2.0

Logic Input Current (DE, DI)

1.0

RECEIVER

Differential Input Threshold Voltage, V_TH–0.2

Input Voltage Hysteresis, ⌬V_TH

Input Resistance

+0.2

–7 V р V_CM

V_CM= 0 V

–7 V р V_CM

V_IN= 12 V

V_IN= –7 V

+12 V

k⍀

µA

Input Current (A, B)

+ 1

–0.8

Logic Enable Input Current (RE)

CMOS Output Voltage Low, V_OL

CMOS Output Voltage High, V_OH

Short Circuit Output Current

0.4

I_OUT= +4.0 mA

I_OUT= –4.0 mA

V_OUT= GND or V_CC

4.0

1.0

Tristate Output Leakage Current

0.4 V р V_OUTр +2.4 V

POWER SUPPLY CURRENT

I_CC(Outputs Enabled)

I_CC(Outputs Disabled)

1.2

0.9

2.0

1.5

OutputsUnloaded,DigitalInputs=GNDorV_CC

Specifications subject to change without notice.

TIMING SPECIFICATIONS (V_CC= +5 V 5ꢀ% All sꢁeciꢂications T_MINto T_MAXunless otherwise noted%)

Parameter

Min Typ

Max

Unit TestConditions/Comments

DRIVER

PropagationDelayInputtoOutputT_PLH,T_PHL

Driver O/P to O/PT_SKEW

DriverRise/FallTimeT_R,T_F

Driver Enable to Output Valid

Driver Disable Timing

R_LDiff = 54 ⍀ C_L1= C_L2= 100 pF, Figure 3

RECEIVER

Propagation Delay Input to Output T_PLH, T_PHL

C_L= 15 pF, Figure 5

Skew |T_PLH–T_PHL

Receiver Enable T_EN1

Receiver Disable T_EN2

Figure 6

Specifications subject to change without notice.

–2–

REV. B

PRELIMINARY TECHNICAL DATA

ADM1486

ABSOLUTE MAXIMUM RATINGS*

(T_A= +25°C unless otherwise noted)

PIN FUNCTION DESCRIPTION

Pin Mnemonic Function

V_CC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7 V

Inputs

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

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

Receiver Inputs (A, B) . . . . . . . . . . . . . . –9 V to +14 V

Outputs

D E

Receiver Output. When enabled if A >B

by 200 mV, then RO = High. If A < B

by 200 mV, then RO = Low.

Receiver Output Enable. A low level

enables the receiver output, RO. A high

level places it in a high impedance state.

Driver Output Enable. A high level

enables the driver differential outputs, A

and B. A low level places it in a high

impedance state.

Driver Outputs . . . . . . . . . . . . . . . . . . . . –9 V to +14 V

Receiver Output . . . . . . . . . . . . . –0.5 V to V_CC+ 0.5 V

Power Dissipation 8-Lead DIP . . . . . . . . . . . . . . 500 mW

θ_JA, Thermal Impedance . . . . . . . . . . . . . . . . +130°C/W

Power Dissipation 8-Lead SOIC . . . . . . . . . . . . 450 mW

θ_JA, Thermal Impedance . . . . . . . . . . . . . . . . +170°C/W

Power Dissipation 8-Lead Cerdip . . . . . . . . . . . . 500 mW

θ_JA, Thermal Impedance . . . . . . . . . . . . . . . . +125°C/W

Power Dissipation 8-Lead µSOIC . . . . . . . . . . . . . . mW

θ_JA, Thermal Impedance . . . . . . . . . . . . . . . . . . . .+°C/W

Operating Temperature Range

Commercial (J Version) . . . . . . . . . . . . . . 0°C to +70°C

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

Driver Input. When the driver is en-

abled a logic Low on DI forces A low

and B high while a logic High on DI

forces A high and B low.

GND

Ground Connection, 0 V.

Noninverting Receiver Input A/Driver

Output A.

Inverting Receiver Input B/Driver

Output B.

Power Supply, 5 V

V_CC

5ꢀ.

*StressesabovethoselistedunderAbsoluteMaximumRatingsmaycausepermanent

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.

PIN CONFIGURATION

C C

ADM 1486

Table I. Transmitting

INPUTS

OUTPUTS

TO P VIEW

R E

(Not to scale)

G ND

Table II. Receiving

ORDERING GUIDE

INPUTS

A-B

OUTPUT

Temperature

Range

Package

Option

R E

Model

у+0.2 V

р –0.2 V

Inputs Open

ADM1486JN

ADM1486JR

ADM1486AN

ADM1486AR

ADM1486ARM

ADM1486AQ

0°C to +70°C

–40°C to +85°C

-40°C to +85°C

–40°C to +85°C

N-8

SO-8

N-8

SO-8

RM-8

Q-8

CAUTION

ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V

readily accumulate on the human body and test equipment and can discharge without

detection. Although the ADM1486 features proprietary ESD protection circuitry,

permanent damage may occur on devices subjected to high-energy electrostatic

discharges. Therefore, proper ESD precautions are recommended to avoid performance

degradation or loss of functionality.

WARNING!

ESD SENSITIVE DEVICE

REV. PrB

–3–

PRELIMINARY TECHNICAL DATA

ADM1486

Test Circuits

0V OR 3V

DE IN

OUT

Figure 4. Driver Enable/Disable Test Circuit

Figure 1. Driver Voltage Measurement Test Circuit

375⍀

OUT

OD3

60⍀

TST

375⍀

Figure 2. Driver Voltage Measurement Test Circuit 2

Figure 5. Receiver Propagation Delay Test Circuit

+1.5V

–1.5V

LDIFF

OUT

RE IN

Figure 3. Driver Propagation Delay Test Circuit

Figure 6. Receiver Enable/Disable Test Circuit

Switching Characteristics

1.5V

PLH

1.5V

A, B

PHL

1/2VO

PHL

PLH

SKEW

1.5V

90% POINT

10% POINT

–VO

Figure 9. Receiver Propagation Delay

Figure 7. Driver Propagation Delay, Rise/Fall Timing

1.5V

+0.5V

2.3V

A, B

O/P LOW

O/P HIGH

+0.5V

–0.5V

Figure 8. Driver Enable/Disable Timing

Figure 10. Receiver Enable/Disable Timing

REV. PrB

–4–

PRELIMINARY TECHNICAL DATA

ADM1486

Figure 11. Typical RS-485 Network

Table III. Comparison of RS-422 and RS-485 Interface Standards

Specification

RS-422

RS-485

PROFIBUS

Transmission Type

Maximum Cable Length

Minimum Driver Output Voltage 2 V

Differential

4000 ft.

Differential

4000 ft.

1.5 V

Differential

2.1 V

Driver Load Impedance

Receiver Input Resistance

Receiver Input Sensitivity

Receiver Input Voltage Range

100

⍀

12 k

200 mV

–7 V to +12 V

32/32

⍀

4 k

⍀

min

⍀

min

200 k⍀ min

200 mV

–7 V to +7 V

200 mV

–7 V to +12 V

50/50

No of Drivers/Receivers Per Line 1/10

REV. PrB

–5–

PRELIMINARY TECHNICAL DATA

ADM1486

flowing through each wire, thereby, reducing the effective

inductance of the pair.

APPLICATIONSINFORMATION

Differential Data Transmission

Differential data transmission is used to reliably transmit

data at high rates over long distances and through noisy

environments. Differential transmission nullifies the effects

of ground shifts and noise signals which appear as

common-mode voltages on the line. There are two main

standards approved by the Electronics Industries Association

(EIA) which specify the electrical characteristics of trans-

ceivers used in differential data transmission.

The ADM1486 is designed for bidirectional data commu-

nications on multipoint transmission lines. A typical

application showing a multipoint transmission network is

illustrated in Figure 11. An RS-485 transmission line can

have as many as 32 transceivers on the bus. Only one

driver can transmit at a particular time but multiple

receivers may be enabled simultaneously.

As with any transmission line, it is important that

reflections are minimized. This may be achieved by

terminating the extreme ends of the line using resistors

equal to the characteristic impedance of the line. Stub

lengths of the main line should also be kept as short as

possible. A properly terminated transmission line appears

purely resistive to the driver.

The RS-422 standard specifies data rates up to 10 MBaud

and line lengths up to 4000 ft. A single driver can drive a

transmission line with up to 10 receivers.

In order to cater for true multipoint communications, the

RS-485 standard was defined. This standard meets or

exceeds all the requirements of RS-422 but also allows for

up to 32 drivers and 32 receivers to be connected to a

single bus. An extended common-mode range of –7 V to

+12 V is defined. The most significant difference between

RS-422 and RS-485 is the fact that the drivers may be

disabled thereby allowing more than one (32 in fact) to be

connected to a single line. Only one driver should be

enabled at time, but the RS-485 standard contains addi-

tional specifications to guarantee device safety in the event

of line contention.

Thermal Shutdown

The ADM1486 contains thermal shutdown circuitry

which protects the part from excessive power dissipation

during fault conditions. Shorting the driver outputs to a

low impedance source can result in high driver currents.

The thermal sensing circuitry detects the increase in die

temperature and disables the driver outputs. The thermal

sensing circuitry is designed to disable the driver outputs

when a die temperature of 150°C is reached. As the device

cools, the drivers are re-enabled at 140°C.

Cable and Data Rate

The transmission line of choice for RS-485

communications is a twisted pair. Twisted pair cable tends

to cancel common-mode noise and also causes cancella-

tion of the magnetic fields generated by the current

Propagation Delay

The ADM1486 features very low propagation delay

ensuring maximum baud rate operation. The driver is

well balanced ensuring distortion free transmission.

Another important specification is a measure of the skew

between the complementary outputs. Excessive skew

impairs the noise immunity of the system and increases

the amount of electromagnetic interference (EMI).

Receiver Open-Circuit Fail Safe

The receiver input includes a fail-safe feature which

guarantees a logic high on the receiver when the inputs

are open circuit or floating.

–6–

REV. PrB

PRELIMINARY TECHNICAL DATA

ADM1486

OUTLINE DIMENSIONS

Dimensions shown in inches and (mm).

8-Lead SOIC (SO-8)

0.1968 (5.00)

0.1890 (4.80)

0.2440 (6.20)

0.2284 (5.80)

0.1574 (4.00)

0.1497 (3.80)

PIN 1

0.0196 (0.50)

0.0099 (0.25)

0.0500 (1.27)

BSC

45؇

0.0688 (1.75)

0.0532 (1.35)

0.0098 (0.25)

0.0040 (0.10)

SEATING

PLANE

8؇

0؇

0.0500 (1.27)

0.0160 (0.41)

0.0192 (0.49)

0.0138 (0.35)

0.0098 (0.25)

0.0075 (0.19)

8-Lead Plastic DIP (N-8)

0.430 (10.92)

0.348 (8.84)

0.280 (7.11)

0.240 (6.10)

0.325 (8.25)

0.300 (7.62)

PIN 1

0.100 (2.54)

BSC

0.060 (1.52)

0.015 (0.38)

0.210

(5.33)

MAX

0.195 (4.95)

0.115 (2.93)

0.130

(3.30)

MIN

0.160 (4.06)

0.115 (2.93)

0.015 (0.381)

0.008 (0.204)

0.022 (0.558) 0.070 (1.77) SEATING

0.014 (0.356) 0.045 (1.15)

PLANE

8-Lead Cerdip (Q-8)

0.055 (1.4)

MAX

0.005 (0.13)

MIN

0.310 (7.87)

0.220 (5.59)

PIN 1

0.320 (8.13)

0.290 (7.37)

0.405 (10.29)

MAX

0.060 (1.52)

0.015 (0.38)

0.200 (5.08)

MAX

0.150

(3.81)

MIN

0.200 (5.08)

0.125 (3.18)

0.015 (0.38)

0.008 (0.20)

SEATING

0.070 (1.78)

0.023 (0.58)

0.100

(2.54)

BSC

15°

0°

PLANE

0.014 (0.36)

0.030 (0.76)

REV. PrB

–7–

PRELIMINARY TECHNICAL DATA

ADM1486

OUTLINE DIMENSIONS

Dimensions shown in inches and (mm).

8-Lead µSOIC (RM-8)

0.122 (3.10)

0.114 (2.90)

0.193

(4.90)

BSC

0.122 (3.10)

0.114 (2.90)

PIN 1

0.0256 (0.65) BSC

0.037 (0.95)

0.030 (0.75)

0.043

(1.10)

MAX

0.006 (0.15)

0.002 (0.05)

6؇

0؇

0.016 (0.40)

SEATING

PLANE

0.028 (0.70)

0.016 (0.40)

0.009 (0.23)

0.005 (0.13)

0.010 (0.25)

–8–

REV. PrB

ADM1486JN [ADI]

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