MAX488

MAX490

1

8

2

7

3

6

4

5

TOP VIEW

RO 2

DI 3

GND 4

B

A

C

RO

R

D

DIP/SO

8

A

7

B

6

Z

5

Y

Z Y

GND

DI

3

DI

D

2

RO

1

5 Y

6 Z

8 A

R

7

Rt

B

4

GND

MAX488

MAX490

Rt

R

RO

D

DI

GND

µMAX

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

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

TOP VIEW

DE

RE

N.C. 1

RO 2

R

RE 3

DE 4

DI 5

D

13 N.C.

DI

5

12 A

11 B

10 Z

RO

2

4

14

D

R

9

Y

10

Z

12

A

Rt

11

MAX489

MAX491

Rt

R

RO

D

DI

GND 6

GND 7

DIP/SO

9

Y

8

N.C.

NC

1, 8, 13

B

3

6, 7

RE GND

GND

DE

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 RS-

422 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 trans-

ceivers 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

MAX481, MAX483, MAX485, MAX487, MAX489,

MAX491, and MAX1487. When disabled, the driver and

receiver outputs are high impedance.

MAX487/MAX1487:

128 Transceivers on the Bus

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 trans-

ceivers 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.