Maxim MAX491MJD, MAX491ESD, MAX491EPD, MAX488MJA, MAX488ESA Datasheet

19-0122; Rev 5; 2/96

Low-Power, Slew-Rate-Limited

RS-485/RS-422 Transceivers

_______________General Description

The MAX481, MAX483, MAX485, MAX487–MAX491, and MAX1487 are low-power transceivers for RS-485 and RS422 communication. Each part contains one driver and one receiver. The MAX483, MAX487, MAX488, and MAX489 feature reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, thus allowing error-free data transmission up to 250kbps. The driver slew rates of the MAX481, MAX485, MAX490, MAX491, and MAX1487 are not limited, allowing them to transmit up to 2.5Mbps.

These transceivers draw between 120µA and 500µA of supply current when unloaded or fully loaded with disabled drivers. Additionally, the MAX481, MAX483, and MAX487 have a low-current shutdown mode in which they consume only 0.1µA. All parts operate from a single 5V supply.

Drivers are short-circuit current limited and are protected against excessive power dissipation by thermal shutdown circuitry that places the driver outputs into a high-impedance state. The receiver input has a fail-safe feature that guarantees a logic-high output if the input is open circuit.

The MAX487 and MAX1487 feature quarter-unit-load receiver input impedance, allowing up to 128 MAX487/ MAX1487 transceivers on the bus. Full-duplex communications are obtained using the MAX488–MAX491, while the MAX481, MAX483, MAX485, MAX487, and MAX1487 are designed for half-duplex applications.

____________________________Features

♦ In µMAX Package: Smallest 8-Pin SO ♦ Slew-Rate Limited for Error-Free Data

Transmission (MAX483/487/488/489)

♦ 0.1µA Low-Current Shutdown Mode

(MAX481/483/487)

♦ Low Quiescent Current:

120µA (MAX483/487/488/489) 230µA (MAX1487) 300µA (MAX481/485/490/491)

♦ -7V to +12V Common-Mode Input Voltage Range ♦ Three-State Outputs ♦ 30ns Propagation Delays, 5ns Skew

(MAX481/485/490/491/1487)

♦ Full-Duplex and Half-Duplex Versions Available ♦ Operate from a Single 5V Supply ♦ Allows up to 128 Transceivers on the Bus

(MAX487/MAX1487)

♦ Current-Limiting and Thermal Shutdown for

Driver Overload Protection

MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487

________________________Applications

Low-Power RS-485 Transceivers Low-Power RS-422 Transceivers Level Translators Transceivers for EMI-Sensitive Applications Industrial-Control Local Area Networks

______________Ordering Information

PART TEMP. RANGE PIN-PACKAGE

MAX481CPA

MAX481CSA 0°C to +70°C 8 SO MAX481CUA 0°C to +70°C 8 µMAX MAX481C/D 0°C to +70°C Dice*

Ordering Information continued at end of data sheet.

0°C to +70°C 8 Plastic DIP

* Contact factory for dice specifications.

______________________________________________________________Selection Table

PART

NUMBER

MAX481 MAX483 MAX485 MAX487 MAX488 MAX489 MAX490 MAX491

MAX1487

HALF/FULL

DUPLEX

Half Half Half Half

Full Full Full Full

Half

DATA RATE

(Mbps)

2.5

0.25

2.5

0.25

2.5

2.5

________________________________________________________________

SLEW-RATE

LIMITED

No

Yes

No Yes Yes Yes

No

No

LOW-POWER

SHUTDOWN

Yes Yes

No

Yes

No No No No No

RECEIVER/

DRIVER

ENABLE

Yes Yes Yes Yes

No

Yes

No Yes Yes

QUIESCENT

CURRENT

(µA)

300 120 300 120 120 120 300 300 230

NUMBER OF

TRANSMITTERS

ON BUS

32 32 32

128

32 32 32 32

128

PIN

COUNT

8 8 8 8 8

14

8

14

8

Maxim Integrated Products

1

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800

Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers

ABSOLUTE MAXIMUM RATINGS

Supply Voltage (VCC).............................................................12V

Control Input Voltage (–R—E–, DE)...................-0.5V to (V

Driver Input Voltage (DI).............................-0.5V to (V

Driver Output Voltage (A, B)...................................-8V to +12.5V

Receiver Input Voltage (A, B).................................-8V to +12.5V

Receiver Output Voltage (RO).....................-0.5V to (V

Continuous Power Dissipation (T

8-Pin Plastic DIP (derate 9.09mW/°C above +70°C) ....727mW

14-Pin Plastic DIP (derate 10.00mW/°C above +70°C)..800mW

8-Pin SO (derate 5.88mW/°C above +70°C).................471mW

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

= +70°C)

A

CC CC

CC

+ 0.5V) + 0.5V)

+0.5V)

DC ELECTRICAL CHARACTERISTICS

(VCC= 5V ±5%, TA= T

Differential Driver Output (no load) Differential Driver Output

(with load)

Change in Magnitude of Driver Differential Output Voltage for Complementary Output States

Driver Common-Mode Output Voltage

Change in Magnitude of Driver Common-Mode Output Voltage for Complementary Output States

Input High Voltage Input Low Voltage Input Current

Input Current (A, B)

Receiver Differential Threshold Voltage

Receiver Input Hysteresis Receiver Output High Voltage Receiver Output Low Voltage

Three-State (high impedance) Output Current at Receiver

Receiver Input Resistance

MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487

MIN

to T

, unless otherwise noted.) (Notes 1, 2)

MAX

OD1

V

I

V

OZR

R

OD2

OC

IN1

IN2

OH

R = 50Ω (RS-422) R = 27Ω (RS-485), Figure 4

R = 27Ω or 50Ω, Figure 4

OD

R = 27Ω or 50Ω, Figure 4

OD

DE, DI, –R—E

IH

DE, DI, –R—E

IL

DE, DI, –R—E DE = 0V;

VCC= 0V or 5.25V, all devices except MAX487/MAX1487

MAX487/MAX1487, DE = 0V, VCC= 0V or 5.25V

-7V ≤ VCM≤ 12V

TH

VCM= 0V

TH

IO= -4mA, VID= 200mV IO = 4mA, VID= -200mV

OL

0.4V ≤ VO≤ 2.4V

-7V ≤ VCM≤ 12V, all devices except MAX487/MAX1487

IN

CM

– – –

≤ 12V, MAX487/MAX1487

14-Pin SO (derate 8.33mW/°C above +70°C)...............667mW

8-Pin µMAX (derate 4.1mW/°C above +70°C)..............830mW

8-Pin CERDIP (derate 8.00mW/°C above +70°C).........640mW

14-Pin CERDIP (derate 9.09mW/°C above +70°C).......727mW

Operating Temperature Ranges

MAX4_ _C_ _/MAX1487C_ A ...............................0°C to +70°C

MAX4_ _E_ _/MAX1487E_ A.............................-40°C to +85°C

MAX4_ _MJ_/MAX1487MJA ...........................-55°C to +125°C

Storage Temperature Range.............................-65°C to +160°C

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

CONDITIONS

2

1.5 5

VIN= 12V

VIN= -7V VIN= 12V

VIN= -7V

3.5V

1.0

-0.8

0.25

-0.2

0.4V

UNITSMIN TYP MAXSYMBOLPARAMETER

V5V V

V0.2∆V

V3V

V0.2∆V

V2.0V V0.8V

µA±2I

mA

V-0.2 0.2

mV70∆V

V V

µA±1I

kΩ12

kΩ48-7V ≤ V

2 _______________________________________________________________________________________

Low-Power, Slew-Rate-Limited

RS-485/RS-422 Transceivers

DC ELECTRICAL CHARACTERISTICS (continued)

(VCC= 5V ±5%, TA= T

No-Load Supply Current (Note 3)

Supply Current in Shutdown Driver Short-Circuit Current,

VO= High Driver Short-Circuit Current,

VO= Low Receiver Short-Circuit Current

MIN

to T

, unless otherwise noted.) (Notes 1, 2)

MAX

MAX488/MAX489, DE, DI, –R—E–= 0V or V

MAX490/MAX491, DE, DI, –R—E–= 0V or V

MAX481/MAX485, –R—E–

I

CC

SHDN

OSD1

OSD2

I

OSR

= 0V or V

MAX1487, –R—E–

= 0V or V

MAX483/MAX487, –R—E–

= 0V or V

CC

CONDITIONS UNITSMIN TYP MAXSYMBOLPARAMETER

CC

DE = V

CC

120 250

300 500 500 900

300 500DE = 0V DE = V DE = 0V

DE = 5V DE = 0V

CC

MAX483 MAX487

CC

300 500

230 400

350 650

250 400

120 250

0.1 10I

7950V ≤ VO≤ V

SWITCHING CHARACTERISTICS—MAX481/MAX485, MAX490/MAX491, MAX1487

(VCC= 5V ±5%, TA= T

Driver Input to Output Driver Output Skew to Output

Driver Rise or Fall Time

Driver Enable to Output High Driver Enable to Output Low Driver Disable Time from Low Driver Disable Time from High

Receiver Input to Output

| t

- t

PLH

| Differential

PHL

Receiver Skew Receiver Enable to Output Low Receiver Enable to Output High Receiver Disable Time from Low Receiver Disable Time from High Maximum Data Rate Time to Shutdown

MIN

to T

, unless otherwise noted.) (Notes 1, 2)

MAX

PLH PHL

SKEW

Figures 6 and 8, R CL1= CL2= 100pF

Figures 6 and 8, R Figures 6 and 8,

R

t

, t

R

F

DIFF

= 54Ω,

CL1= CL2= 100pF Figures 7 and 9, CL= 100pF, S2 closed

ZH

Figures 7 and 9, CL= 100pF, S1 closed

ZL

Figures 7 and 9, CL= 15pF, S1 closed

LZ

Figures 7 and 9, CL= 15pF, S2 closed

HZ

Figures 6 and 10, R

t

PLH

, t

PHL

DIFF

= 54Ω,

CL1= CL2= 100pF

t

SKD

MAX

SHDN

Figures 6 and 10, R CL1= CL2= 100pF

Figures 5 and 11, CRL= 15pF, S1 closed

ZL

Figures 5 and 11, CRL= 15pF, S2 closed

ZH

Figures 5 and 11, CRL= 15pF, S1 closed

LZ

Figures 5 and 11, CRL= 15pF, S2 closed

HZ

MAX481 (Note 5)

CONDITIONS

DIFF

= 54Ω,

10 30 60t 10 30 60t

= 54Ω, CL1= CL2= 100pF

DIFF

MAX481, MAX485, MAX1487 MAX490C/E, MAX491C/E MAX490M, MAX491M

31540 51525 31540

510t

40 70t 40 70t

40 70t

MAX481, MAX485, MAX1487

20 90 200 MAX490C/E, MAX491C/E 20 90 150 MAX490M, MAX491M

= 54Ω,

DIFF

20 90 200

13

20 50t

MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487

µA

µAMAX481/483/487, DE = 0V, –R—E–= V

mA35 250-7V ≤ VO≤12V (Note 4)I

mA35 250-7V ≤ VO≤12V (Note 4)I mA

UNITSMIN TYP MAXSYMBOLPARAMETER

ns ns

ns

ns ns ns40 70t ns

ns

ns ns20 50t

ns20 50t ns ns20 50t

Mbps2.5f

ns50 200 600t

_______________________________________________________________________________________ 3

Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers

SWITCHING CHARACTERISTICS—MAX481/MAX485, MAX490/MAX491, MAX1487 (continued)

(VCC= 5V ±5%, TA= T

Driver Enable from Shutdown to Output High (MAX481)

Driver Enable from Shutdown to Output Low (MAX481)

Receiver Enable from Shutdown to Output High (MAX481)

Receiver Enable from Shutdown to Output Low (MAX481)

MIN

to T

, unless otherwise noted.) (Notes 1, 2)

MAX

ZH(SHDN)

ZL(SHDN)

ZH(SHDN)

t

ZL(SHDN)

Figures 7 and 9, CL= 100pF, S2 closed

Figures 7 and 9, CL= 100pF, S1 closed

Figures 5 and 11, CL= 15pF, S2 closed, A - B = 2V

Figures 5 and 11, CL= 15pF, S1 closed, B - A = 2V

CONDITIONS

300 1000

UNITSMIN TYP MAXSYMBOLPARAMETER

ns40 100t

ns300 1000t

ns

SWITCHING CHARACTERISTICS—MAX483, MAX487/MAX488/MAX489

(VCC= 5V ±5%, TA= T

Driver Input to Output

Driver Output Skew to Output ns100 800

Driver Rise or Fall Time Driver Enable to Output High

Driver Enable to Output Low Driver Disable Time from Low Driver Disable Time from High

Receiver Input to Output

I t

- t

PLH

I Differential

PHL

Receiver Skew Receiver Enable to Output Low Receiver Enable to Output High Receiver Disable Time from Low Receiver Disable Time from High Maximum Data Rate Time to Shutdown Driver Enable from Shutdown to

Output High Driver Enable from Shutdown to

Output Low Receiver Enable from Shutdown

to Output High Receiver Enable from Shutdown

to Output Low

MIN

to T

, unless otherwise noted.) (Notes 1, 2)

MAX

t

PLH

t

PHL

t

SKEW

ZH

ZL LZ

HZ

t

PLH

t

PHL

t

SKD

ZL

ZH

LZ

HZ

MAX

SHDN

t

ZH(SHDN)

t

ZL(SHDN)

t

ZH(SHDN)

t

ZL(SHDN)

Figures 6 and 8, R CL1= CL2= 100pF

Figures 6 and 8, R

F

CL1= CL2= 100pF Figures 7 and 9, CL= 100pF, S2 closed

Figures 7 and 9, CL= 100pF, S1 closed Figures 7 and 9, CL= 15pF, S1 closed Figures 7 and 9, CL= 15pF, S2 closed

Figures 6 and 10, R CL1= CL2= 100pF

Figures 5 and 11, CRL= 15pF, S1 closed Figures 5 and 11, CRL= 15pF, S2 closed Figures 5 and 11, CRL= 15pF, S1 closed Figures 5 and 11, CRL= 15pF, S2 closed t

, t

PLH

PHL

MAX483/MAX487, Figures 7 and 9, CL= 100pF, S2 closed

MAX483/MAX487, Figures 7 and 9, CL= 100pF, S1 closed

MAX483/MAX487, Figures 5 and 11, CL= 15pF, S2 closed

MAX483/MAX487, Figures 5 and 11, CL= 15pF, S1 closed

CONDITIONS

= 54Ω,

DIFF

= 54Ω,

DIFF

= 54Ω,

DIFF

= 54Ω,

DIFF

= 54Ω,

DIFF

< 50% of data period

250 800 2000 250 800 2000

250 2000t

300 3000t 250 2000 250 2000

100

20 50t

UNITSMIN TYP MAXSYMBOLPARAMETER

ns

ns250 2000tR, t ns

ns250 2000t ns300 3000t ns

ns

ns ns20 50t

ns20 50t ns ns20 50t

kbps250f

ns50 200 600MAX483/MAX487 (Note 5) t ns2000

ns2000

ns2500

MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487

4 _______________________________________________________________________________________

Low-Power, Slew-Rate-Limited

RS-485/RS-422 Transceivers

NOTES FOR ELECTRICAL/SWITCHING CHARACTERISTICS

Note 1: All currents into device pins are positive; all currents out of device pins are negative. All voltages are referenced to device

ground unless otherwise specified.

Note 2: All typical specifications are given for V

= 5V and TA= +25°C.

CC

Note 3: Supply current specification is valid for loaded transmitters when DE = 0V. Note 4: Applies to peak current. See

Typical Operating Characteristics.

Note 5: The MAX481/MAX483/MAX487 are put into shutdown by bringing–R—E–high and DE low. If the inputs are in this state for less

than 50ns, the parts are guaranteed not to enter shutdown. If the inputs are in this state for at least 600ns, the parts are guaranteed to have entered shutdown. See

Low-Power Shutdown Mode

section.

__________________________________________Typical Operating Characteristics

(VCC= 5V, TA = +25°C, unless otherwise noted.)

OUTPUT CURRENT vs.

RECEIVER OUTPUT LOW VOLTAGE

45 40 35

30 25 20 15

OUTPUT CURRENT (mA)

10

5 0

0.5 1.0 2.0

0 2.5

OUTPUT LOW VOLTAGE (V)

1.5

-20

-18

MAX481-01

-16

-14

-12

-10

-8

-6

OUTPUT CURRENT (mA)

-4

-2 0

1.5 2.0 3.0 5.0

OUTPUT CURRENT vs.

RECEIVER OUTPUT HIGH VOLTAGE

2.5 4.0

OUTPUT HIGH VOLTAGE (V)

3.5 4.5

RECEIVER OUTPUT HIGH VOLTAGE vs.

4.8

4.6

MAX481-02

4.4

4.2

4.0

3.8

3.6

3.4

OUTPUT HIGH VOLTAGE (V)

3.2

3.0

-50 -25 25 75

TEMPERATURE

IRO = 8mA

050 TEMPERATURE (°C)

100

125

MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487

MAX481-03

RECEIVER OUTPUT LOW VOLTAGE vs.

TEMPERATURE

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

OUTPUT LOW VOLTAGE (V)

0.1 0

-50 -25 25 75

050 TEMPERATURE (°C)

_______________________________________________________________________________________

IRO = 8mA

100

125

90

MAX481-04

80 70 60 50 40 30

OUTPUT CURRENT (mA)

20 10

0

DRIVER OUTPUT CURRENT vs.

DIFFERENTIAL OUTPUT VOLTAGE

0 1.0 3.0 4.5

0.5 1.5 2.5 3.5 DIFFERENTIAL OUTPUT VOLTAGE (V)

2.0 4.0

DRIVER DIFFERENTIAL OUTPUT VOLTAGE

vs. TEMPERATURE

2.4

2.3

MAX481-05

2.2

2.1

2.0

1.9

1.8

1.7

DIFFERENTIAL OUTPUT VOLTAGE (V)

1.6

1.5

-50 -25 25 125

075 TEMPERATURE (°C)

R = 54Ω

10050

MAX481-06

5

Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers

____________________________Typical Operating Characteristics (continued)

(VCC= 5V, TA = +25°C, unless otherwise noted.)

OUTPUT CURRENT vs.

DRIVER OUTPUT LOW VOLTAGE

140

120

100

80

60

40

OUTPUT CURRENT (mA)

20

0

24

08

OUTPUT LOW VOLTAGE (V)

6

10

MAX483/MAX487–MAX489

SUPPLY CURRENT vs. TEMPERATURE

600

500

400

300

MAX487; DE = VCC, RE = X 

200

MAX483/MAX487; DE = RE = 0, MAX488/MAX489; DE = RE = X

SUPPLY CURRENT (µA)

100

MAX483/MAX487; DE = 0, RE = V

0

-50 -25 50 100

-120

MAX481-07

-100

-80

-60

-40

OUTPUT CURRENT (mA)

-20

0

12

MAX483; DE = VCC, RE = X

0

TEMPERATURE (°C)

-7 -5 -1 5

25 75

OUTPUT CURRENT vs.

DRIVER OUTPUT HIGH VOLTAGE

-6 -4 -2 0 2 4

-3 1

OUTPUT HIGH VOLTAGE (V)

SUPPLY CURRENT vs. TEMPERATURE

600

MAX481-12

500

400

MAX1487; DE = VCC, RE = X

300



200

MAX1487; DE = 0V, RE = X

SUPPLY CURRENT (µA)

100

CC

125

0

-40-60 -20 40 100 120

3

SUPPLY CURRENT vs. TEMPERATURE

600

MAX481-08

500

400

300

200

SUPPLY CURRENT (µA)

100

0

-50 -25 50 100

MAX1487

20 60 80

0

TEMPERATURE (°C)

MAX481/MAX485/MAX490/MAX491

MAX481/MAX485; DE = VCC, RE = X

MAX485; DE = 0, RE = X, MAX481; DE = RE = 0 MAX490/MAX491; DE = RE = X

MAX481; DE = 0, RE = V

0 TEMPERATURE (°C)

140

CC

25 75

MAX481-13

MAX481-11

125

MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487

6 _______________________________________________________________________________________

Low-Power, Slew-Rate-Limited

RS-485/RS-422 Transceivers

______________________________________________________________Pin Description

MAX481/MAX483/ MAX485/MAX487/

MAX1487

DIP/SO DIP/SO

2 3

3 4

4 5

5 6, 7 Ground — 9 Noninverting Driver Output — 10 Inverting Driver Output

6 — Noninverting Receiver Input and Noninverting Driver Output

µMAX

4

5

6

7 — —

8

MAX488/

MAX490

DIP/SO

µMAX

2 RO

—

3

4 5 6

—

MAX489/

MAX491

431 2

5

6 7 8

NAME

–R—E–

DE

DI

GND

Y Z A

FUNCTION FUNCTIONNAME

Receiver Output: If A > B by 200mV, RO will be high; If A < B by 200mV, RO will be low.

Receiver Output Enable. RO is enabled when–R—E–is low; RO is high impedance when–R—E–is high.

Driver Output Enable. The driver outputs, Y and Z, are enabled by bringing DE high. They are high impedance when DE is low. If the driver outputs are enabled, the parts function as line drivers. While they are high impedance, they function as line receivers if

–R—E–

is low.

Driver Input. A low on DI forces output Y low and output Z high. Similarly, a high on DI forces output Y high and output Z low.

MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487

—

2

A

1 3

CC

Positive Supply: 4.75V ≤ VCC≤ 5.25V

— 12 Noninverting Receiver Input

7 — — B Inverting Receiver Input and Inverting Driver Output

— 7 11 B Inverting Receiver Input

8 1 14 V

— — 1, 8, 13 N.C. No Connect—not internally connected

—

8

1

2

TOP VIEW

RO

2

RE

3

DE

4

DI

D

DIP/SO

1

B

V

CC

2

MAX481

3 4

MAX483 MAX485 MAX487

MAX1487

RO RE

µMAX

8

V

CC

7

B

6

A

R

1

5

GND

A

8 7

GND DI

6

DE

5

RO

2

RE

3

DE

4

DI

NOTE: PIN LABELS Y AND Z ON TIMING, TEST, AND WAVEFORM DIAGRAMS REFER TO PINS A AND B WHEN DE IS HIGH. TYPICAL OPERATING CIRCUIT SHOWN WITH DIP/SO PACKAGE.

D

8

V

CC

B

7

Rt

6

A

5

GND

MAX481 MAX483 MAX485 MAX487 MAX1487

B

Rt

A

R

1

Figure 1. MAX481/MAX483/MAX485/MAX487/MAX1487 Pin Configuration and Typical Operating Circuit

DE

D

R

DI

RO

RE

_______________________________________________________________________________________ 7

Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers

TOP VIEW

V

GND

A

1

CC

RO

DI

R

2 3 4

D

8

B

7 6

Z Y

5

3

DI

V

CC

1



5

DR

6

DIP/SO

2

B

1

A

2

MAX488

V

CC

RO

MAX490

3 4



8

Z

7

Y

6

GND

5

DI

RO

µMAX

4

GND

8

R

7

NOTE: TYPICAL OPERATING CIRCUIT SHOWN WITH DIP/SO PACKAGE.

Figure 2. MAX488/MAX490 Pin Configuration and Typical Operating Circuit

TOP VIEW

N.C.

RO RE DE

GND GND

1

R

2 3 4 5

DI

6 7

D

14 13 12 11 10 9 8

V

CC

N.C. A B Z Y N.C.

RO

NC

DI

1, 8, 13

DIP/SO

DE V

CC

144

5

D

2

3 6, 7

9 10

12

RD

11

RE GND

V

CC

MAX488 MAX490



Y Z

A

Rt

B

Rt

D

GND

VCCRE

RO

DI

MAX489 MAX491



Y

Z

A

Rt

B

Rt

R

GND DE

RO

DI

Figure 3. MAX489/MAX491 Pin Configuration and Typical Operating Circuit

__________Applications Information

The MAX481/MAX483/MAX485/MAX487–MAX491 and MAX1487 are low-power transceivers for RS-485 and RS422 communications. The MAX481, MAX485, MAX490, MAX491, and MAX1487 can transmit and receive at data rates up to 2.5Mbps, while the MAX483, MAX487, MAX488, and MAX489 are specified for data rates up to 250kbps. The MAX488–MAX491 are full-duplex transceivers while the MAX481, MAX483, MAX485, MAX487, and MAX1487 are half-duplex. In addition, Driver Enable (DE) and Receiver Enable (RE) pins are included on the

The 48kΩ, MAX487 and MAX1487 allows up to 128 transceivers on a bus, compared to the 1-unit load (12kΩ input impedance) of standard RS-485 drivers (32 transceivers maximum). Any combination of MAX487/ MAX1487 and other RS-485 transceivers with a total of 32 unit loads or less can be put on the bus. The MAX481/MAX483/MAX485 and MAX488–MAX491 have standard 12kΩ Receiver Input impedance.

1

/

-unit-load receiver input impedance of the

4

128 Transceivers on the Bus

MAX487/MAX1487:

MAX481, MAX483, MAX485, MAX487, MAX489, MAX491, and MAX1487. When disabled, the driver and

MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487

receiver outputs are high impedance.

8 _______________________________________________________________________________________

Low-Power, Slew-Rate-Limited

RS-485/RS-422 Transceivers

_________________________________________________________________Test Circuits

Y

R

V

OD

R

V

OC

Z

RECEIVER

OUTPUT

TEST POINT

C

RL

15pF

1k

Figure 4. Driver DC Test Load Figure 5. Receiver Timing Test Load

3V

DE

DI

Y

V

ID

Z

C

L1

R

DIFF

C

L2

A

RO

B

RE

OUTPUT

UNDER TEST

500Ω

C

L

S1

S2

1k

V

CC

V

S1

S2

CC

MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487

Figure 6. Driver/Receiver Timing Test Circuit Figure 7. Driver Timing Test Load

MAX483/MAX487/MAX488/MAX489:

Reduced EMI and Reflections

The MAX483 and MAX487–MAX489 are slew-rate limited, minimizing EMI and reducing reflections caused by improperly terminated cables. Figure 12 shows the driver output waveform and its Fourier analysis of a

monics with large amplitudes are evident. Figure 13 shows the same information displayed for a MAX483, MAX487, MAX488, or MAX489 transmitting under the same conditions. Figure 13’s high-frequency harmonics have much lower amplitudes, and the potential for EMI is significantly reduced.

150kHz signal transmitted by a MAX481, MAX485, MAX490, MAX491, or MAX1487. High-frequency har-

_______________________________________________________________________________________ 9

Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers

_______________________________________________________Switching Waveforms

3V

DI

V

DIFF

1.5V

0V

Z

V

O

Y

1/2 V

O

V

O

0V

-V

10%

O

t

R

t

90%

PLH

V

t

SKEW =

= V (Y) - V (Z)

DIFF

t

PHL

| t

- t

PLH

PHL

1.5V 1/2 V

O

90%

t

F

|

10%

3V

DE

Y, Z V

Y, Z

1.5V 1.5V

0V

t

, t

ZL(SHDN)

ZL

2.3V

OL

0V

OUTPUT NORMALLY LOW

OUTPUT NORMALLY HIGH

2.3V

t

, t

ZH(SHDN)

ZH

t

LZ

V

+0.5V

OL

V

-0.5V

OH

t

HZ

Figure 8. Driver Propagation Delays Figure 9. Driver Enable and Disable Times (except MAX488 and

MAX490)

3V

RO

A-B

RE

0V

V

OH

V

OL

V

ID

-V

0V

ID

1.5V

OUTPUT

t

PHL

INPUT

t

1.5V

PLH

0V

V

CC

RO

0V

1.5V 1.5V

t

, t

ZL(SHDN)

ZL

1.5V

OUTPUT NORMALLY LOW

OUTPUT NORMALLY HIGH

1.5V

t

, t

ZH(SHDN)

ZH

t

LZ

t

HZ

V

+ 0.5V

OL

OH

- 0.5V

Figure 10. Receiver Propagation Delays

Figure 11. Receiver Enable and Disable Times (except MAX488 and MAX490)

_________________Function Tables

(MAX481/MAX483/MAX485/MAX487/MAX1487)

Table 1. Transmitting Table 2. Receiving

INPUTS OUTPUTS

RE

X

0

1

X = Don't care

MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487

High-Z = High impedance

Shutdown mode for MAX481/MAX483/MAX487

*

DE DI Z Y

1

0

0

1

0

X

X

0

1

High-Z

High-Z

High-Z

High-Z

*

1

0

*

RE DE A-B RO

0

1

X = Don't care High-Z = High impedance

Shutdown mode for MAX481/MAX483/MAX487

*

10 ______________________________________________________________________________________

INPUTS OUTPUT

0

0

> +0.2V

< -0.2V

Inputs open

X

1

0

1

High-Z

*

Low-Power, Slew-Rate-Limited

RS-485/RS-422 Transceivers

MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487

10dB/div

0Hz 5MHz

Figure 12. Driver Output Waveform and FFT Plot of MAX481/ MAX485/MAX490/MAX491/MAX1487 Transmitting a 150kHz Signal

500kHz/div

Low-Power Shutdown Mode

(MAX481/MAX483/MAX487)

A low-power shutdown mode is initiated by bringing both –R—E–high and DE low. The devices will not shut down unless both the driver and receiver are disabled. In shutdown, the devices typically draw only 0.1µA of supply current.

–R—E–

and DE may be driven simultaneously; the parts are guaranteed not to enter shutdown if –R—E–is high and DE is low for less than 50ns. If the inputs are in this state for at least 600ns, the parts are guaranteed to enter shutdown.

For the MAX481, MAX483, and MAX487, the tZHand tZLenable times assume the part was not in the lowpower shutdown state (the MAX485/MAX488–MAX491 and MAX1487 can not be shut down). The t and t

ZL(SHDN)

down (see It takes the drivers and receivers longer to become

enabled from the low-power shutdown state (t

ZH(SHDN

(tZH, tZL). (The parts are in operating mode if the –R—E–, DE inputs equal a logical 0,1 or 1,1 or 0, 0.)

enable times assume the parts were shut

Electrical Characteristics

), t

ZL(SHDN)

) than from the operating mode

).

ZH(SHDN)

10dB/div

0Hz 5MHz

Figure 13. Driver Output Waveform and FFT Plot of MAX483/ MAX487–MAX489 Transmitting a 150kHz Signal

500kHz/div

Driver Output Protection

Excessive output current and power dissipation caused by faults or by bus contention are prevented by two mechanisms. A foldback current limit on the output stage provides immediate protection against short circuits over the whole common-mode voltage range (see

Typical Operating Characteristics

mal shutdown circuit forces the driver outputs into a high-impedance state if the die temperature rises excessively.

). In addition, a ther-

Propagation Delay

Many digital encoding schemes depend on the difference between the driver and receiver propagation delay times. Typical propagation delays are shown in Figures 15–18 using Figure 14’s test circuit.

The difference in receiver delay times, | t typically under 13ns for the MAX481, MAX485, MAX490, MAX491, and MAX1487 and is typically less than 100ns for the MAX483 and MAX487–MAX489.

The driver skew times are typically 5ns (10ns max) for the MAX481, MAX485, MAX490, MAX491, and MAX1487, and are typically 100ns (800ns max) for the MAX483 and MAX487–MAX489.

PLH

- t

PHL

|, is

______________________________________________________________________________________ 11

Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers

100pF

TTL IN

, tF < 6ns

t

R

Z

D

Y

R = 54Ω

100pF

Figure 14. Receiver Propagation Delay Test Circuit

B

R

A

RECEIVER OUT

A

500mV/div

B

RO

2V/div

20ns/div

VCC = 5V

= +25°C

T

A

Figure 15. MAX481/MAX485/MAX490/MAX491/MAX1487 Receiver t

500mV/div

2V/div

RO

PHL

A

B

VCC = 5V

= +25°C

T

A

B

500mV/div

A

2V/div

RO

20ns/div

VCC = 5V

= +25°C

T

A

Figure 16. MAX481/MAX485/MAX490/MAX491/MAX1487 Receiver t

500mV/div

2V/div

PLH

B

VCC = 5V

= +25°C

T

A

RO

400ns/div

Figure 17. MAX483, MAX487–MAX489 Receiver t

MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487

PHL

Figure 18. MAX483, MAX487–MAX489 Receiver t

400ns/div

PLH

12 ______________________________________________________________________________________

Low-Power, Slew-Rate-Limited

RS-485/RS-422 Transceivers

Line Length vs. Data Rate

The RS-485/RS-422 standard covers line lengths up to 4000 feet. For line lengths greater than 4000 feet, see Figure 23.

Figures 19 and 20 show the system differential voltage for the parts driving 4000 feet of 26AWG twisted-pair wire at 110kHz into 120Ω loads.

Typical Applications

The MAX481, MAX483, MAX485, MAX487–MAX491, and MAX1487 transceivers are designed for bidirectional data communications on multipoint bus transmission lines.

DI

V

Y-VZ

RO

5V 0V

1V 0V

-1V

5V 0V

Figures 21 and 22 show typical network applications circuits. These parts can also be used as line repeaters, with cable lengths longer than 4000 feet, as shown in Figure 23.

To minimize reflections, the line should be terminated at both ends in its characteristic impedance, and stub lengths off the main line should be kept as short as possible. The slew-rate-limited MAX483 and MAX487–MAX489 are more tolerant of imperfect termination.

5V 0V

1V 0V

-1V

5V 0V

V

DI

Y-VZ

RO

MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487

2µs/div

Figure 19. MAX481/MAX485/MAX490/MAX491/MAX1487 System Differential Voltage at 110kHz Driving 4000ft of Cable

120Ω

DI

D

DE

RO

RE

R

MAX481

B

A

B

A

D

R

Figure 20. MAX483, MAX487–MAX489 System Differential Voltage at 110kHz Driving 4000ft of Cable

120Ω

B

A

R

D

MAX483 MAX485 MAX487

DI RO DE

DE

DI

RO

RERE

MAX1487

Figure 21. MAX481/MAX483/MAX485/MAX487/MAX1487 Typical Half-Duplex RS-485 Network

______________________________________________________________________________________ 13

2µs/div

B

A

DE

D

DI

R

RO RE

Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers

A

RO

RE

DE

DI

R

D

120Ω

B

Z

120Ω

Y

Z

Y

AA

BB

R

D

DI DIRO RO

DE DE

RE

NOTE: RE AND DE ON MAX489/MAX491 ONLY.

Figure 22. MAX488–MAX491 Full-Duplex RS-485 Network

MAX488–MAX491

Y

120Ω

Z

B

120Ω

Z

Y

A

D

R

DI

DE RE

RO

R

D

MAX488 MAX489 MAX490

RE

MAX491

Isolated RS-485

For isolated RS-485 applications, see the MAX253 and MAX1480 data sheets.

A

RO

RE

DE

DI

R

D

120Ω

B

Z

120Ω

Y

DATA IN

DATA OUT

NOTE: RE AND DE ON MAX489/MAX491 ONLY.

Figure 23. Line Repeater for MAX488–MAX491

MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487

14 ______________________________________________________________________________________

Low-Power, Slew-Rate-Limited

RS-485/RS-422 Transceivers

__Ordering Information (continued)

PIN-PACKAGETEMP. RANGEPART

8 Plastic DIP-40°C to +85°CMAX481EPA 8 SO-40°C to +85°CMAX481ESA 8 CERDIP-55°C to +125°CMAX481MJA

MAX483CPA

MAX485CPA

MAX487CPA

MAX488CPA

MAX489CPD

8 Plastic DIP0°C to +70°C 8 SO0°C to +70°CMAX483CSA 8 µMAX0°C to +70°CMAX483CUA Dice*0°C to +70°CMAX483C/D 8 Plastic DIP-40°C to +85°CMAX483EPA 8 SO-40°C to +85°CMAX483ESA 8 CERDIP-55°C to +125°CMAX483MJA 8 Plastic DIP0°C to +70°C 8 SO0°C to +70°CMAX485CSA 8 µMAX0°C to +70°CMAX485CUA Dice*0°C to +70°CMAX485C/D 8 Plastic DIP-40°C to +85°CMAX485EPA 8 SO-40°C to +85°CMAX485ESA 8 CERDIP-55°C to +125°CMAX485MJA 8 Plastic DIP0°C to +70°C 8 SO0°C to +70°CMAX487CSA 8 µMAX0°C to +70°CMAX487CUA Dice*0°C to +70°CMAX487C/D 8 Plastic DIP-40°C to +85°CMAX487EPA 8 SO-40°C to +85°CMAX487ESA 8 CERDIP-55°C to +125°CMAX487MJA 8 Plastic DIP0°C to +70°C 8 SO0°C to +70°CMAX488CSA 8 µMAX0°C to +70°CMAX488CUA Dice*0°C to +70°CMAX488C/D 8 Plastic DIP-40°C to +85°CMAX488EPA 8 SO-40°C to +85°CMAX488ESA 8 CERDIP-55°C to +125°CMAX488MJA 14 Plastic DIP0°C to +70°C 14 SO0°C to +70°CMAX489CSD Dice*0°C to +70°CMAX489C/D 14 Plastic DIP-40°C to +85°CMAX489EPD 14 SO-40°C to +85°CMAX489ESD 14 CERDIP-55°C to +125°CMAX489MJD

__Ordering Information (continued)

PIN-PACKAGETEMP. RANGEPART

MAX490CPA

MAX491CPD

MAX1487CPA

* Contact factory for dice specifications.

8 Plastic DIP0°C to +70°C 8 SO0°C to +70°CMAX490CSA 8 µMAX0°C to +70°CMAX490CUA Dice*0°C to +70°CMAX490C/D 8 Plastic DIP-40°C to +85°CMAX490EPA 8 SO-40°C to +85°CMAX490ESA 8 CERDIP-55°C to +125°CMAX490MJA 14 Plastic DIP0°C to +70°C 14 SO0°C to +70°CMAX491CSD Dice*0°C to +70°CMAX491C/D 14 Plastic DIP-40°C to +85°CMAX491EPD 14 SO-40°C to +85°CMAX491ESD 14 CERDIP-55°C to +125°CMAX491MJD 8 Plastic DIP0°C to +70°C 8 SO0°C to +70°CMAX1487CSA 8 µMAX0°C to +70°CMAX1487CUA Dice*0°C to +70°CMAX1487C/D 8 Plastic DIP-40°C to +85°CMAX1487EPA 8 SO-40°C to +85°CMAX1487ESA 8 CERDIP-55°C to +125°CMAX1487MJA

_________________Chip Topographies

MAX481/MAX483/MAX485/MAX487/MAX1487

V

CC

RO

RE

DE

DI

GND

0.080"

(2.032mm)

N.C. N.C.

0.054"

B

(1.372mm)

A

MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487

______________________________________________________________________________________ 15

Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers

_____________________________________________Chip Topographies (continued)

MAX489/MAX491

V

CC

GND

0.080"

(2.032mm)

A B

0.054"

Z

(1.372mm)

Y

N.C.

RO

DI

MAX488/MAX490

V

CC

GND

0.080"

(2.032mm)

A B

0.054"

Z

(1.372mm)

Y

RO

RE

DE

DI

TRANSISTOR COUNT: 248

SUBSTRATE CONNECTED TO GND

________________________________________________________Package Information

DIM

C

A

0.101mm

e

A1B

0.004 in

L

α

A

A1

B C D E

H

INCHES MILLIMETERS



MIN

0.036

0.004

0.010

0.005

0.116

e

0.188

L

0.016

α

MAX

0.044

0.008

0.014

0.007

0.120



0°



0.198

0.026 6°

MIN

0.91

0.10

0.25

0.13

2.95

4.78

0.41 0°

MAX

1.11

0.20

0.36

0.18

3.05

0.650.0256



5.03

0.66 6°

21-0036D

E H

8-PIN µMAX

MICROMAX SMALL-OUTLINE

PACKAGE

D

MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

16

__________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600

Maxim MAX491MJD, MAX491ESD, MAX491EPD, MAX488MJA, MAX488ESA Datasheet

Specifications and Main Features

Frequently Asked Questions

User Manual