_________________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/C) if the
input is open circuit.
The MAX1480A/MAX1480B/MAX1480C/MAX1490A/
MAX1490B typically withstand 1600V
RMS
(1 minute) or
2000V
RMS
(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
MAX1480A/B/C/MAX1490A/B
Complete, Isolated RS-485/RS-422
Data Interface
________________________________________________________________
Maxim Integrated Products
1
1
24
23
22
21
20
19
18
17
2
3
4
5
6
7
8
AC1
AC2
ISO V
CC1
ISO RO DRV
D2
D1
A
B
Z
Y
SD
FS
GND1
16
15
14
13
9
10
11
12
ISO COM1
ISO DI DRV
ISO V
CC2
ISO RO LED
GND2
RO
DI
DIP
V
CC2
V
CC3
V
CC4
V
CC1
MAX1490A/B
MAX845
MAX488 MAX490
TOP VIEW
ISOLATION BARRIER
Pin Configurations
19-0259; Rev 4; 10/03
_______________Ordering Information
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.
Pin Configurations continued at end of data sheet.
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
PART
TEMP RANGE
PIN-PACKAGE
MAX1480A
CPI
0°C to +70°C
28 Wide Plastic DIP
MAX1480AEPI
-40°C to +85°C
28 Wide Plastic DIP
_____________________Selection Table
PART
HALF/
FULL
DUPLEX
DATA
RATE
(MBPS)
SLEW-
RATE
LIMITED
DRIVER
ENABLE
TIME
(µS)
MAX1480A
Half
2.5
No
0.2
MAX1480B
Half
0.25
Yes
35
MAX1480C
Half
0.25
Yes
0.5
MAX1490A
Full
2.5
No
--
MAX1490B
Full
0.25
Yes
--
Complete, Isolated RS-485/RS-422
Data Interface
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
CC_
= 5V ±10%, V
FS
= V
CC_
, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC_
= 5V and T
A
= +25°C.) (Notes 1, 2)
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.
With Respect to GND_
Supply Voltage (V
CC_
)...........................................-0.3V to +6V
Control Input Voltage (SD, FS)...............-0.3V to (V
CC_
+ 0.3V)
Receiver Output Voltage (RO, RO)........-0.3V to (V
CC_
+ 0.3V)
Output Switch Voltage (D1, D2)........................................+12V
With Respect to ISO COM_
Control Input Voltage (ISO DE_ ) ....-0.3V to (ISO V
CC_
+ 0.3V)
Driver Input Voltage (ISO DI_ ) .......-0.3V to (ISO V
CC_
+ 0.3V)
Receiver Output Voltage (ISO RO_) ...-0.3V to (ISO V
CC_
+ 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 (T
A
= +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
MAX1480A/B/C/MAX1490A/B
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
f
SWL
V
FS
= 0V
535
Switch Frequency
f
SWH
FS = V
CC_
or open
725
kHz
R
L
=
, +25
°
C only
60
90
MAX1480A,
DE
´
= V
CC_
or open
R
L
= 54
120
R
L
=
, +25
°
C only
35
45
MAX1480B,
DE
´
= V
CC_
or open
R
L
= 54
95
R
L
=
, +25
°
C only
35
75
MAX1480C,
DE
´
= V
CC_
or open
R
L
= 54
95
R
L
=
, +25
°
C only
100
150
MAX1490A
R
L
= 54
170
R
L
=
, +25
°
C only
65
125
Operating Supply Current
I
CC
MAX1490B
R
L
= 54
130
mA
Shutdown Supply Current
(Note 3)
I
SHDN
SD = V
CC_
0.2
µA
V
SDH
High
2.4
Shutdown Input Threshold
V
SDL
Low
0.8
V
Shutdown Input Leakage Current
10
pA
V
FSH
High
2.4
FS Input Threshold
V
FSL
Low
0.8
V
FS Input Pullup Current
FS low
50
µA
FS Input Leakage Current
FS high
10
pA
Input High Voltage
V
IH
DE
´
, DI
´
V
CC_
- 0.4
V
Input Low Voltage
V
IL
DE
´
, DI
´
0.4
V
Isolation Resistance
R
ISO
T
A
= +25
°
C, V
ISO
= 50VDC
100
10,000
M
Isolation Capacitance
C
ISO
T
A
= +25
°
C, V
ISO
= 50VDC
10
pF
Differential Driver Output
(No Load)
V
OD1
8
V
MAX1480A/B/C/MAX1490A/B
Complete, Isolated RS-485/RS-422
Data Interface
_______________________________________________________________________________________
3
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
R = 50
(RS-422)
2
Differential Driver Output
(With Load)
V
OD2
R = 27
(RS-485), Figure 4
1.5
5.0
V
Differential
0.3
Change in Magnitude of
Differential Output Voltage for
Complementary Output States
V
OD
R = 27
or 50
,
Figure 4
Common mode
0.3
V
Driver Common-Mode Output
Voltage
V
OC
R = 27
or 50
, Figure 4
4
V
MAX1490A/B
0.25
V
IN
= 12V
MAX1480A/B/C
1
MAX1490A/B
0.2
Input Current (A, B)
ISO I
IN
DE
´
= 0V,
V
CC_
= 0V
or 5.5V
V
IN
= -7V
MAX1480A/B/C
0.8
mA
Receiver Input Resistance
R
IN
-7V
V
CM
12V
12
k
Receiver Differential Threshold
Voltage
V
TH
-7V
V
CM
12V
-0.2
+0.2
V
Receiver Input Hysteresis
V
TH
V
CM
= 0V
70
mV
Receiver Output/Receiver Output
Low Voltage
V
OL
Using resistor values listed in
Tables 1 and 2
0.4
V
Receiver Output/Receiver Output
High Current
I
OH
V
OUT
= 5.5V
250
µA
Driver Short-Circuit Current
ISO I
OSD
-7V
V
O
12V (Note 4)
100
mA
ELECTRICAL CHARACTERISTICS (continued)
(V
CC_
= 5V ±10%, V
FS
= V
CC_
, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC_
= 5V and T
A
= +25°C.) (Notes 1, 2)
SWITCHING CHARACTERISTICS--MAX1480A/MAX1490A
(V
CC_
= 5V ±10%, FS = V
CC_
, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC_
= 5V and TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
t
PLH
100
275
Driver Input to Output
Propagation Delay
t
PHL
Figures 5 and 7, R
DIFF
= 54
, C
L1
= C
L2
= 100pF
100
275
ns
Driver Output Skew
t
SKEW
Figures 5 and 7, R
DIFF
= 54
, C
L1
= C
L2
= 100pF
25
90
ns
Driver Rise or Fall Time
t
R,
t
F
Figures 5 and 7, R
DIFF
= 54
, C
L1
= C
L2
= 100pF
15
40
ns
Driver Enable to Output High
(MAX1480A Only)
t
ZH
Figures 6 and 8, C
L
= 100pF, S2 closed
0.2
1.5
µs
Driver Enable to Output Low
(MAX1480A Only)
t
ZL
Figures 6 and 8, C
L
= 100pF, S1 closed
0.2
1.5
µs
Driver Disable Time from Low
(MAX1480A Only)
t
LZ
Figures 6 and 8, C
L
= 15pF, S1 closed
0.2
1.5
µs
Driver Disable Time from High
(MAX1480A Only)
t
HZ
Figures 6 and 8, C
L
= 15pF, S2 closed
0.2
1.5
µs
t
PLH
100
225
Receiver Input to Output
Propagation Delay
t
PHL
Figures 5 and 10, R
DIFF
= 54
, C
L1
= C
L2
= 100pF
100
225
ns
MAX1480A/B/C/MAX1490A/B
Complete, Isolated RS-485/RS-422
Data Interface
4
_______________________________________________________________________________________
SWITCHING CHARACTERISTICS--MAX1480A/MAX1490A (continued)
(V
CC_
= 5V ±10%, FS = V
CC_
, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC_
= 5V and TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
|t
PLH
- t
PHL
| Differential Receiver
Skew
t
SKD
Figures 5 and 10, R
DIFF
= 54
, C
L1
= C
L2
= 100pF
20
ns
Maximum Data Rate
f
MAX
t
PLH
, t
PHL
< 50% of data period
2.5
Mbps
Time to Shutdown
t
SHDN
100
µs
Shutdown to Driver Output High
t
ZH(SHDN)
Figures 6 and 9, C
L
= 100pF, S2 closed
3
10
µs
Shutdown to Driver Output Low
t
ZL(SHDN)
Figures 6 and 9, C
L
= 100pF, S1 closed
3
10
µs
SWITCHING CHARACTERISTICS--MAX1480B/MAX1480C/MAX1490B
(V
CC_
= 5V ±10%, FS = V
CC_
, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC_
= 5V and TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
t
PLH
2
3.0
Driver Input to Output
Propagation Delay
t
PHL
Figures 5 and 7, R
DIFF
= 54
,
C
L1
= C
L2
= 100pF
2
3.0
µs
Driver Output Skew
t
SKEW
Figures 5 and 7, R
DIFF
= 54
,
C
L1
= C
L2
= 100pF
900
1600
ns
Driver Rise or Fall Time
t
R,
t
F
Figures 5 and 7, R
DIFF
= 54
,
C
L1
= C
L2
= 100pF
1.0
2.0
µs
Driver Enable to Output High
(MAX1480B Only)
t
ZH
Figures 6 and 8, C
L
= 100pF, S2 closed
35
100
µs
Driver Enable to Output Low
(MAX1480B Only)
t
ZL
Figures 6 and 8, C
L
= 100pF, S1 closed
35
100
µs
Driver Disable Time from Low
(MAX1480B Only)
t
LZ
Figures 6 and 8, C
L
= 15pF, S1 closed
13
50
µs
Driver Disable Time from High
(MAX1480B Only)
t
HZ
Figures 6 and 8, C
L
= 15pF, S2 closed
13
50
µs
Driver Enable to Output High
(MAX1480C Only)
t
ZH
Figures 6 and 8, C
L
= 100pF, S2 closed
0.5
4.5
µs
Driver Enable to Output Low
(MAX1480C Only)
t
ZL
Figures 6 and 8, C
L
= 100pF, S1 closed
0.5
4.5
µs
MAX1480A/B/C, MAX1490A/B
Complete, Isolated RS-485/RS-422
Data Interface
_______________________________________________________________________________________
5
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 V
CC1
and V
CC2
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).
SWITCHING CHARACTERISTICS--MAX1480B/MAX1480C/MAX1490B (continued)
(V
CC_
= 5V ±10%, FS = V
CC_
, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC_
= 5V and TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Driver Disable Time from Low
(MAX1480C Only)
t
LZ
Figures 6 and 8, C
L
= 15pF, S1 closed
2.0
4.5
µs
Driver Disable Time from High
(MAX1480C Only)
t
HZ
Figures 6 and 8, C
L
= 15pF, S2 closed
2.0
4.5
µs
t
PLH
2
3.0
Receiver Input to Output
Propagation Delay
t
PHL
Figures 5 and 10, R
DIFF
= 54
,
C
L1
= C
L2
= 100pF
2
3.0
µs
|t
PLH
- t
PHL
| Differential Receiver
Skew
t
SKD
Figures 5 and 10, R
DIFF
= 54
,
C
L1
= C
L2
= 100pF
1200
ns
Maximum Data Rate
f
MAX
t
PLH
, t
PHL
< 50% of data period
0.25
Mbps
Time to Shutdown
t
SHDN
100
µs
Shutdown to Driver Output High
t
ZH(SHDN)
Figures 6 and 9, C
L
= 100pF, S2 closed
35
100
µs
Shutdown to Driver Output Low
t
ZL(SHDN)
Figures 6 and 9, C
L
= 100pF, S1 closed
35
100
µs
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