Complete, Isolated RS-485/RS-422 Data Interface

Complete, Isolated RS-485/RS-422
Data Interface

19-0259; Rev 5; 5/05

_________________General Description
The MAX1480A/MAX1480B/MAX1480C/MAX1490A/
MAX1490B are complete, electrically isolated, RS-485/
RS-422 data-communications interface solutions in a
hybrid microcircuit. Transceivers, optocouplers, and a
transformer provide a complete interface in a standard
DIP package. A single +5V supply on the logic side pow-
ers both sides of the interface.

The MAX1480B/MAX1480C/MAX1490B feature reduced-
slew-rate drivers that minimize EMI and reduce reflec-
tions caused by improperly terminated cables, allowing
error-free data transmission at data rates up to 250kbps.
The MAX1480A/MAX1490A driver slew rate is not limited,
allowing transmission rates up to 2.5Mbps. The
MAX1480A/B/C are designed for half-duplex communi-
cation, while the MAX1490A/B feature full-duplex com-
munication.

Drivers are short-circuit current limited and protected
against excessive power dissipation by thermal shut-
down circuitry that places the driver outputs into a high-
impedance state. The receiver input has a fail-safe
feature that guarantees a known output (RO low for the
MAX1480A/B/C, RO high for the MAX1490A/B) if the
input is open circuit.

The MAX1480A/MAX1480B/MAX1480C/MAX1490A/
MAX1490B typically withstand 1600VRMS (1 minute) or
2000VRMS (1 second). Their isolated outputs meet all
RS-485/RS-422 specifications. The MAX1480A/B/C are
available in a 28-pin DIP package, and the MAX1490A/B
are available in a 24-pin DIP package.
________________________Applications

Isolated RS-485/RS-422 Data Interface

Transceivers for EMI-Sensitive Applications

Industrial-Control Local Area Networks

Automatic Test Equipment

HVAC/Building Control Networks

Next-Generation Device Features

♦♦ For Integrated ESD Protection

MAX1480E/MAX1490E: ±15kV ESD-Protected,
Isolated RS-485/RS-422 Data Interfaces

♦♦ For Space-Constrained Applications

MAX3157: High CMRR, RS-485 Transceiver with
±50V Isolation

_______________Ordering Information

PART†

TEMP RANGE

PIN-PACKAGE

MAX1480ACPI

0°C to +70°C

28 Wide Plastic DIP

MAX1480AEPI

-40°C to +85°C

28 Wide Plastic DIP

Ordering Information continued at end of data sheet.
†Data rate for “A” parts is up to 2.5Mbps. Data rate for “B” and
“C” parts is up to 250kbps.

_____________________Selection Table

HALF/
FULL
DUPLEX

DATA
RATE
(MBPS)

SLEW-
RATE
LIMITED

Half

Half

Half

Full

Full

2.5

0.25

0.25

2.5

0.25

No

Yes

Yes

No

Yes

DRIVER
ENABLE
TIME
(µs)

0.2

35

0.5

—

—

Pin Configurations

PART

MAX1480A

MAX1480B

MAX1480C

MAX1490A

MAX1490B

TOP VIEW

/

/

M
A
X
1
4
8
0
A
B
C
M
A
X
1
4
9
0
A
B

/

/

FS

6

5
4
8
X
A
M

8
8
4
X
A
M

0
9
4
X
A
M

VCC1

VCC2

D1

D2

GND1

SD

VCC3

DI

VCC4

RO

GND2

1

2

3

4

5

7

8

9

10

11

12

24

AC1

MAX1490A/B

23

AC2

ISO VCC1

ISO RO DRV

A

B

Z

Y

22

21

20

19

18

17

15

14

16

ISO COM1

ISO DI DRV

ISO VCC2

13

ISO RO LED

ISOLATION BARRIER
DIP

Pin Configurations continued at end of data sheet.

________________________________________________________________ Maxim Integrated Products 1

For pricing, delivery, and ordering information,please contact Maxim Directat 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.

/

/

B
A
0
9
4
1
X
A
M
C
B
A
0
8
4
1
X
A
M

/

/

Complete, Isolated RS-485/RS-422
Data Interface

ABSOLUTE MAXIMUM RATINGS
With Respect to GND_

Supply Voltage (VCC_)…………………………………….-0.3V to +6V
Control Input Voltage (SD, FS)……………-0.3V to (VCC_ + 0.3V)
Receiver Output Voltage (RO, RO)……..-0.3V to (VCC_ + 0.3V)
Output Switch Voltage (D1, D2)………………………………….+12V

With Respect to ISO COM_

Control Input Voltage (ISO DE_ ) ….-0.3V to (ISO VCC_ + 0.3V)
Driver Input Voltage (ISO DI_ ) …….-0.3V to (ISO VCC_ + 0.3V)
Receiver Output Voltage (ISO RO_) …-0.3V to (ISO VCC_ + 0.3V)
Driver Output Voltage (A, B, Y, Z ) ………………….-8V to +12.5V
Receiver Input Voltage (A, B)…………………………-8V to +12.5V

LED Forward Current (DI, DE, ISO RO LED) ………………….50mA
Continuous Power Dissipation (TA = +70°C)

24-Pin Plastic DIP (derate 8.7mW°C above +70°C) …..696mW
28-Pin Plastic DIP (derate 9.09mW/°C above +70°C) ..727mW

Operating Temperature Ranges

MAX1480_CPI/MAX1490_CPG ……………………….0°C to +70°C
MAX1480_EPI/MAX1490_EPG …………………….-40°C to +85°C
Storage Temperature Range ………………………..-65°C to +160°C
Lead Temperature (soldering, 10s) ……………………………+300°C

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.

ELECTRICAL CHARACTERISTICS
(VCC_ = 5V ±10%, VFS = VCC_, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC_ = 5V and TA = +25°C.) (Notes 1, 2)

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

Switch Frequency

fSWL
fSWH

VFS = 0V
FS = VCC_ or open

MAX1480A,
DE´ = VCC_ or open

MAX1480B,
DE´ = VCC_ or open

MAX1480C,
DE´ = VCC_ or open

MAX1490A

MAX1490B

RL = ∞, +25°C only
RL = 54Ω
RL = ∞, +25°C only
RL = 54Ω
RL = ∞, +25°C only
RL = 54Ω
RL = ∞, +25°C only
RL = 54Ω
RL = ∞, +25°C only
RL = 54Ω

Operating Supply Current

ICC

Shutdown Supply Current
(Note 3)

Shutdown Input Threshold

Shutdown Input Leakage Current

FS Input Threshold

FS Input Pullup Current

FS Input Leakage Current

Input High Voltage

Input Low Voltage

Isolation Resistance

Isolation Capacitance

Differential Driver Output
(No Load)

ISHDN

SD = VCC_

High

Low

High

Low

FS low

FS high

DE´, DI´

VSDH
VSDL

VFSH
VFSL

VIH
VIL
RISO
CISO

VOD1

DE´, DI´
TA = +25°C, VISO = 50VDC
TA = +25°C, VISO = 50VDC

535

725

60

120

35

95

35

95

100

170

65

130

0.2

10

10

10

90

45

75

150

125

0.8

0.8

50

0.4

8

2.4

2.4

VCC_ – 0.4

100

10,000

kHz

mA

µA

pA

V

V

µA

pA

V

V
MΩ
pF

V

2

_______________________________________________________________________________________

Complete, Isolated RS-485/RS-422
Data Interface

ELECTRICAL CHARACTERISTICS (continued)
(VCC_ = 5V ±10%, VFS = VCC_, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC_ = 5V and TA = +25°C.) (Notes 1, 2)

PARAMETER

SYMBOL

CONDITIONS

TYP

MAX

UNITS

Differential Driver Output
(With Load)

Change in Magnitude of
Differential Output Voltage for
Complementary Output States

Driver Common-Mode Output
Voltage

VOD2

ΔVOD

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

R = 27Ω or 50Ω,
Figure 4

Differential

Common mode

VOC

R = 27Ω or 50Ω, Figure 4

DE´ = 0V,
VCC_ = 0V
or 5.5V

VIN = 12V

VIN = -7V

MAX1480A/B/C

MAX1490A/B

MAX1480A/B/C

MAX1490A/B

MAX1480A/B/C

MAX1490A/B

Input Current (A, B)

ISO IIN

Receiver Input Resistance

RIN

-7V ≤ VCM ≤ 12V

Receiver Differential Threshold
Voltage

Receiver Input Hysteresis

Receiver Output/Receiver Output
Low Voltage

Receiver Output/Receiver Output
High Current

VTH

ΔVTH

VOL

-7V ≤ VCM ≤ 12V

VCM = 0V
Using resistor values listed in
Tables 1 and 2

IOH

VOUT = 5.5V

Driver Short-Circuit Current

ISO IOSD

-7V ≤ VO ≤ 12V (Note 4)

MIN

2

1.5

48

12

-0.2

SWITCHING CHARACTERISTICS—MAX1480A/MAX1490A
(VCC_ = 5V ±10%, FS = VCC_, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC_ = 5V and TA = +25°C.)

PARAMETER

SYMBOL

MIN

MAX

UNITS

tPLH
tPHL

tSKEW

tR, tF

tZL

tLZ

Driver Input to Output
Propagation Delay

Driver Output Skew

Driver Rise or Fall Time

Driver Enable to Output High
(MAX1480A Only)

Driver Enable to Output Low
(MAX1480A Only)

Driver Disable Time from Low
(MAX1480A Only)

Driver Disable Time from High
(MAX1480A Only)

Receiver Input to Output
Propagation Delay

CONDITIONS
Figures 5 and 7, RDIFF = 54Ω, CL1 = CL2
= 100pF

Figures 5 and 7, RDIFF = 54Ω, CL1 = CL2
= 100pF

Figures 5 and 7, RDIFF = 54Ω, CL1 = CL2
= 100pF

tZH

Figures 6 and 8, CL = 100pF, S2 closed

0.2

1.5

Figures 6 and 8, CL = 100pF, S1 closed

0.2

1.5

Figures 6 and 8, CL = 15pF, S1 closed

0.2

1.5

tHZ

Figures 6 and 8, CL = 15pF, S2 closed

tPLH
tPHL

Figures 5 and 10, RDIFF = 54Ω, CL1 = CL2
= 100pF

0.2

100

100

1.5

225

225

_______________________________________________________________________________________ 3

/

/

M
A
X
1
4
8
0
A
B
C
M
A
X
1
4
9
0
A
B

/

/

5.0

0.3

0.3

4

1

0.25

0.8

0.2

+0.2

0.4

250

275

275

90

40

70

100

TYP

100

100

25

15

V

V

V

mA

kΩ

mV

V

V

µA

mA

ns

ns

ns

µs

µs

µs

µs

ns

/

/

B
A
0
9
4
1
X
A
M
C
B
A
0
8
4
1
X
A
M

/

/

Complete, Isolated RS-485/RS-422
Data Interface

SWITCHING CHARACTERISTICS—MAX1480A/MAX1490A (continued)
(VCC_ = 5V ±10%, FS = VCC_, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC_ = 5V and TA = +25°C.)

PARAMETER

SYMBOL

MIN

TYP

MAX

UNITS

|tPLH – tPHL| Differential Receiver
Skew

Maximum Data Rate

Time to Shutdown

Shutdown to Driver Output High

Shutdown to Driver Output Low

tSKD

fMAX
tSHDN
tZH(SHDN)
tZL(SHDN)

CONDITIONS
Figures 5 and 10, RDIFF = 54Ω, CL1 = CL2
= 100pF

tPLH, tPHL < 50% of data period 2.5 Figures 6 and 9, CL = 100pF, S2 closed Figures 6 and 9, CL = 100pF, S1 closed 20 100 3 3 Mbps ns µs µs µs 10 10 SWITCHING CHARACTERISTICS—MAX1480B/MAX1480C/MAX1490B (VCC_ = 5V ±10%, FS = VCC_, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC_ = 5V and TA = +25°C.) PARAMETER SYMBOL MIN TYP MAX UNITS tPLH tPHL tSKEW tR, tF tZL tLZ CONDITIONS Figures 5 and 7, RDIFF = 54Ω, CL1 = CL2 = 100pF Figures 5 and 7, RDIFF = 54Ω, CL1 = CL2 = 100pF Figures 5 and 7, RDIFF = 54Ω, CL1 = CL2 = 100pF tZH Figures 6 and 8, CL = 100pF, S2 closed Figures 6 and 8, CL = 100pF, S1 closed Figures 6 and 8, CL = 15pF, S1 closed tHZ Figures 6 and 8, CL = 15pF, S2 closed Driver Input to Output Propagation Delay Driver Output Skew Driver Rise or Fall Time Driver Enable to Output High (MAX1480B Only) Driver Enable to Output Low (MAX1480B Only) Driver Disable Time from Low (MAX1480B Only) Driver Disable Time from High (MAX1480B Only) Driver Enable to Output High (MAX1480C Only) Driver Enable to Output Low (MAX1480C Only) tZH Figures 6 and 8, CL = 100pF, S2 closed 0.5 4.5 tZL Figures 6 and 8, CL = 100pF, S1 closed 0.5 4.5 2 2 3.0 3.0 900 1600 1.0 2.0 35 35 13 13 100 100 50 50 µs ns µs µs µs µs µs µs µs 4 _______________________________________________________________________________________ Complete, Isolated RS-485/RS-422 Data Interface SWITCHING CHARACTERISTICS—MAX1480B/MAX1480C/MAX1490B (continued) (VCC_ = 5V ±10%, FS = VCC_, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC_ = 5V and TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS tLZ Figures 6 and 8, CL = 15pF, S1 closed 2.0 4.5 Driver Disable Time from Low (MAX1480C Only) Driver Disable Time from High (MAX1480C Only) Receiver Input to Output Propagation Delay |tPLH - tPHL| Differential Receiver Skew Maximum Data Rate Time to Shutdown Shutdown to Driver Output High Shutdown to Driver Output Low tHZ Figures 6 and 8, CL = 15pF, S2 closed tPLH tPHL tSKD Figures 5 and 10, RDIFF = 54Ω, CL1 = CL2 = 100pF Figures 5 and 10, RDIFF = 54Ω, CL1 = CL2 = 100pF fMAX tSHDN tZH(SHDN) tZL(SHDN) Figures 6 and 9, CL = 100pF, S2 closed Figures 6 and 9, CL = 100pF, S1 closed µs µs µs ns µs µs µs 2.0 2 2 1200 100 35 35 4.5 3.0 3.0 100 100 tPLH, tPHL < 50% of data period 0.25 Mbps Note 1: All currents into device pins are positive; all currents out of device pins are negative. All voltages are referenced to logic- side ground (GND_), unless otherwise specified. Note 2: For DE´ and DI´ pin descriptions, see Detailed Block Diagram and Typical Application Circuit (Figure 1 for MAX1480A/ MAX1480B/MAX1480C, Figure 2 for MAX1490A/MAX1490B). Note 3: Shutdown supply current is the current at VCC1 and VCC2 when shutdown is enabled. Note 4: Applies to peak current (see Typical Operating Characteristics). Although the MAX1480A/B/C and MAX1490A/B provide electrical isolation between logic ground and signal paths, they do not provide isolation between external shields and the signal paths (see Isolated Common Connection section). / / M A X 1 4 8 0 A B C , M A X 1 4 9 0 A B / _______________________________________________________________________________________ 5