19-1941; Rev 1; 3/06
±15kV ESD-Protected, Isolated, 3.3V
RS-485/RS-422 Data Interfaces
General Description
The MAX3480EA/MAX3480EB are electrically isolated
RS-485/RS-422 data-communications interfaces. The
RS-485/RS-422 I/O pins are protected against ±15kV
electrostatic discharge (ESD) shocks, without latchup.
Transceivers, optocouplers, and a transformer are all
included in one low-cost, 28-pin PDIP package. A sin-
gle +3.3V supply on the logic side powers both sides
of the interface.
The MAX3480EB features reduced-slew-rate drivers
that minimize EMI and reduce reflections caused by
improperly terminated cables, allowing error-free data
transmission at data rates up to 160kbps. The
MAX3480EA’s driver slew rate is not limited, allowing
transmission rates up to 2.5Mbps.
Drivers are short-circuit current limited and are protect-
ed 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 MAX3480EA/MAX3480EB are guaranteed to with-
stand 1260V
RMS
(1min) or 1520V
RMS
(1s). Their isolated
inputs and outputs meet RS-485/RS-422 specifications.
____________________________Features
♦
Isolated Data Interface Guaranteed to 1260V
RMS
(1min)
♦
±15kV ESD Protection for I/O Pins
♦
Slew-Rate-Limited Data Transmission (160kbps for
MAX3480EB)
♦
High-Speed, Isolated, 2.5Mbps RS-485 Interface
(MAX3480EA)
♦
Single +3.3V Supply
♦
Current Limiting and Thermal Shutdown for
Driver Overload Protection
♦
Standard 28-Pin PDIP Package
♦
Allows Up to 128 Transceivers on the Bus
MAX3480EA/MAX3480EB
Pin Configuration
TOP VIEW
MAX3480EA
MAX3480EB
V
CC1
1
V
CC2
D1
D2
GND1
FS
2
3
4
5
6
7
8
9
MAX845
MAX1487E
MAX487E
28 AC1
27 AC2
26 ISO V
CC1
25 B
24 ISO RO DRV
23 A
22 ISO DI IN
21 ISO DE IN
20 ISO COM1
19 ISO DI DRV
18 ISO V
CC2
17 ISO DE DRV
16 ISO COM2
15 ISO RO LED
________________________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
Telecom
Ordering Information
PART
MAX3480EACPI
MAX3480EBCPI
TEMP
RANGE
DATA
PIN-
PKG
RATE
CODE
PACKAGE*
(kbps)
2500 P28M-1
2500 P28M-1
250
250
P28M-1
P28M-1
SD
V
CC3
DI
V
CC4
10
DE 11
GND2 12
RO 13
V
CC5
14
0°C to +70°C 28 PDIP
0°C to +70°C 28 PDIP
MAX3480EAEPI -40°C to +85°C 28 PDIP
MAX3480EBEPI -40°C to +85°C 28 PDIP
*See
the Reliability section at end of data sheet.
ISOLATION BARRIER
PDIP
________________________________________________________________
Maxim Integrated Products
1
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.
±15kV ESD-Protected, Isolated, 3.3V
RS-485/RS-422 Data Interfaces
MAX3480EA/MAX3480EB
ABSOLUTE MAXIMUM RATINGS
With Respect to GND
Supply Voltage (V
CC1,
V
CC2,
V
CC4,
V
CC5
) .......-0.3V to +3.8V
Supply Voltage (V
CC3
) ........................................-0.3V to +7V
Control Input Voltage (SD, FS) ............-0.3V to (V
CC3
+ 0.3V)
Receiver Output Voltage (RO).............-0.3V to (V
CC5
+ 0.3V)
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)..............................-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)
28-Pin PDIP (derate 9.09mW/°C above +70°C)............727mW
Operating Temperature Ranges
MAX3480E_CPI..................................................0°C to +70°C
MAX3480E_EPI ...............................................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°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
(V
CC
= V
CC1
= V
CC2
= V
CC4
= V
CC5
= +3.0V to +3.6V, FS = 0, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC
=
+3.3V and T
A
= +25°C.) (Notes 1, 2)
PARAMETER
Switch Frequency
SYMBOL
f
SWL
f
SWH
FS = 0
FS = V
CC
or open
MAX3480EA,
DE´ = V
CC
or open
MAX3480EB,
DE´ = V
CC
or open
SD = V
CC3
High
Low
FS low
FS high
DE´, DI´, Figure 1
DE´, DI´, Figure 1
T
A
= +25°C, 1min (Note 4)
High
Low
T
A
= +25°C, V
ISO
= ±50VDC
f = 1MHz
A, B, Y, and Z pins, tested at Human Body
Model
100
1260
2.4
1
1
10,000
10
±15
8
R = 50Ω (RS-422)
R = 27Ω (RS-485), Figure 3
R = 27Ω or 50Ω,
Figure 3
Differential
Common mode
2
1.5
5.0
0.3
V
0.3
0.8
V
CC
- 0.4
0.4
10
2.4
0.8
50
R
L
=
∞
R
L
= 54Ω
R
L
=
∞
R
L
= 54Ω
CONDITIONS
MIN
TYP
60
900
130
220
80
180
0.2
µA
V
µA
pA
V
V
V
RMS
V
MΩ
pF
kV
V
V
200
250
mA
MAX
UNITS
kHz
Operating Supply Current
I
CC
Shutdown Supply Current (Note 3)
FS Input Threshold
FS Input Pullup Current
FS Input Leakage Current
Input High Voltage
Input Low Voltage
Isolation Voltage
Shutdown Input Threshold
Isolation Resistance
Isolation Capacitance
ESD Protection
Differential Driver Output
(No Load)
Differential Driver Output
Change in Magnitude of Driver
Output Voltage for Complementary
Output States
I
SHDN
V
FSH
V
FSL
I
FSL
I
FSM
V
IH
V
IL
V
ISO
V
SDH
V
SDL
R
ISO
C
ISO
ESD
V
OD1
V
OD2
∆V
OD
2
_______________________________________________________________________________________
±15kV ESD-Protected, Isolated, 3.3V
RS-485/RS-422 Data Interfaces
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= V
CC1
= V
CC2
= V
CC4
= V
CC5
= +3.0V to +3.6V, FS = 0, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC
=
+3.3V and T
A
= +25°C.) (Notes 1, 2)
PARAMETER
Driver Common-Mode Output
SYMBOL
V
OC
CONDITIONS
R = 27Ω or 50Ω, Figure 4
DE´ = 0,
V
CC
= 0 or
+3.6V
MAX3480EA
MAX3480EB
V
IN
= +12V
V
IN
= -7V
V
IN
= +12V
V
IN
= -7V
48
-0.2
70
0.4
250
100
+0.2
MIN
TYP
MAX
4
0.25
-0.2
0.25
-0.2
kΩ
V
mV
V
µA
mA
mA
UNITS
V
MAX3480EA/MAX3480EB
Input Current (A, B)
ISO I
IN
Receiver Input Resistance
Receiver Differential Threshold
Receiver Input Hysteresis
Receiver Output Low Voltage
Receiver Output High Current
Driver Short-Circuit Current
R
IN
V
TH
∆V
TH
V
OL
I
OH
ISO I
OSD
-7V
≤
V
CM
≤
12V
-7V
≤
V
CM
≤
12V
V
CM
= 0
DI´ = V
CC
V
OUT
= +3.6V, DI´ = 0
-7V
≤
V
O
≤
12V (Note 5)
SWITCHING CHARACTERISTICS—MAX3480EA
(V
CC
= V
CC1
= V
CC2
= V
CC4
= V
CC5
= +3.0V to +3.6V, FS = 0, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at
V
CC
= +3.3V and T
A
= +25°C.)
PARAMETER
Driver Input to Output
Propagation Delay
Driver Output Skew
Driver Rise or Fall Time
Driver Enable to Output High
Driver Enable to Output Low
Driver Disable Time from High
Driver Disable Time from Low
Receiver Input to Output
Propagation Delay
SYMBOL
t
PLH
t
PHL
t
SKEW
t
R
, t
F
t
ZH
t
ZL
t
HZ
t
LZ
t
PLH
t
PHL
t
SKD
f
MAX
CONDITIONS
Figures 4, 6; R
DIFF
= 54Ω,
C
L1
= C
L2
= 100pF
Figures 4, 6; R
DIFF
= 54Ω,
C
L1
= C
L2
= 100pF (Note 5)
Figures 4, 6; R
DIFF
= 54Ω,
C
L1
= C
L2
= 100pF
Figures 5, 7; C
L
= 100pF, S2 closed
Figures 5, 7; C
L
= 100pF, S1 closed
Figures 5, 7; C
L
= 15pF, S2 closed
Figures 5, 7; C
L
= 15pF, S1 closed
Figures 4, 8; R
DIFF
= 54Ω,
C
L1
= C
L2
= 100pF
Figures 4, 8; R
DIFF
= 54Ω,
C
L1
= C
L2
= 100pF
t
SKEW
, t
SKD
≤
25% of data period
2.5
MIN
TYP
100
100
25
15
0.5
0.5
0.6
0.6
100
120
20
MAX
275
275
100
50
1.8
1.8
1.8
1.8
225
225
100
UNITS
ns
ns
ns
µs
µs
µs
µs
ns
ns
Mbps
t
PLH
- t
PHL
Differential
Receiver Skew
Maximum Data Rate
_______________________________________________________________________________________
3
±15kV ESD-Protected, Isolated, 3.3V
RS-485/RS-422 Data Interfaces
MAX3480EA/MAX3480EB
SWITCHING CHARACTERISTICS—MAX3480EB
(V
CC
= V
CC1
= V
CC2
= V
CC4
= V
CC5
= +3.0V to +3.6V, FS = 0, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at
V
CC
= +3.3V and T
A
= +25°C.)
PARAMETER
Driver Input to Output
Propagation Delay
Driver Output Skew
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
Propagation Delay
SYMBOL
t
PLH
t
PHL
t
SKEW
t
R
, t
F
t
ZH
t
ZL
t
LZ
t
HZ
t
PLH
t
PHL
t
SKD
f
MAX
CONDITIONS
Figures 4, 6; R
DIFF
= 54Ω,
C
L1
= C
L2
= 100pF
Figures 4, 6; R
DIFF
= 54Ω,
C
L1
= C
L2
= 100pF
Figures 4, 6; R
DIFF
= 54Ω,
C
L1
= C
L2
= 100pF
Figures 5, 7; C
L
= 100pF, S2 closed
Figures 5, 7; C
L
= 100pF, S1 closed
Figures 5, 7; C
L
= 15pF, S1 closed
Figures 5, 7; C
L
= 15pF, S2 closed
Figures 4, 8; R
DIFF
= 54Ω,
C
L1
= C
L2
= 100pF
Figures 4, 8; R
DIFF
= 54Ω,
C
L1
= C
L2
= 100pF
t
SKEW
, t
SKD
≤
25% of data period
160
MIN
TYP
1.5
1.2
300
1.0
1.2
1.0
1.5
2.0
0.6
1.4
750
MAX
3.0
3.0
1200
2.0
4.5
4.5
4.5
4.5
3.0
3.0
1500
UNITS
µs
ns
µs
µs
µs
µs
µs
µs
ns
kbps
t
PLH
- t
PHL
Differential
Receiver Skew
Maximum Data Rate
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 (GND1, GND2), unless otherwise specified.
Note 2:
For DE
´
and DI
´
pin descriptions, see the
Block Diagram
and the
Typical Application Circuit
(Figure 1 for
MAX3480EA/MAX3480EB).
Note 3:
Shutdown supply current is the current at V
CC1
when shutdown is enabled.
Note 4:
Limit guaranteed by applying 1520VRMS for 1s. Test voltage is applied between all pins on one side of the package to all
pins on the other side of the package. For example, between pins 1 and 14, and 15 and 28.
Note 5:
Applies to peak current. See the
Typical Operating Characteristics
and the
Applications Information
section.
4
_______________________________________________________________________________________
±15kV ESD-Protected, Isolated, 3.3V
RS-485/RS-422 Data Interfaces
MAX3480EA/MAX3480EB
__________________________________________Typical Operating Characteristics
(V
CC_
= +3.3V, T
A
= +25°C, Figure 1, unless otherwise noted.)
DRIVER DIFFERENTIAL OUTPUT VOLTAGE
vs. TEMPERATURE
MAX3480EA/EB toc01
OUTPUT CURRENT
vs. DRIVER OUTPUT HIGH VOLTAGE
MAX3480EA/EB toc02
OUTPUT CURRENT
vs. DRIVER OUTPUT LOW VOLTAGE
160
OUTPUT CURRENT (mA)
140
120
100
80
60
40
20
0
MAX3480EA/EB toc03
3.0
DIFFERENTIAL OUTPUT VOLTAGE (V)
2.9
2.8
2.7
2.6
2.5
2.4
2.3
2.2
2.1
2.0
-40
DI
´
= HIGH OR OPEN
R
L
= 54Ω
-100
-90
-80
OUTPUT CURRENT (mA)
-70
-60
-50
-40
-30
-20
-10
0
180
-20
0
20
40
60
80
-6
-4
-2
0
2
4
6
0
2
4
6
8
10
12
TEMPERATURE (°C)
OUTPUT HIGH VOLTAGE (V)
OUTPUT LOW VOLTAGE (V)
RECEIVER OUTPUT LOW VOLTAGE
vs. TEMPERATURE
MAX3480EA/EB toc04
RECEIVER OUTPUT HIGH VOLTAGE
vs. TEMPERATURE
4.75
OUTPUT HIGH VOLTAGE (V)
4.50
4.25
4.00
3.75
3.50
3.25
3.00
MEASURED AT ISO RO DRV
I
RO
= 8mA
MAX3480EA/EB toc05
0.8
0.7
OUTPUT LOW VOLTAGE (V)
0.6
0.5
0.4
0.3
0.2
0.1
0
-40
MEASURED AT ISO RO DRV
I
RO
= 8mA
5.00
-20
0
20
40
60
80
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
TEMPERATURE (°C)
OUTPUT CURRENT
vs. RECEIVER OUTPUT LOW VOLTAGE
MAX3480EA/EB toc06
OUTPUT CURRENT
vs. RECEIVER OUTPUT HIGH VOLTAGE
MEASURED AT ISO RO DRV
70
OUTPUT CURRENT (mA)
60
50
40
30
20
10
0
MAX3480EA/EB toc07
80
70
OUTPUT CURRENT (mA)
60
50
40
30
20
10
0
0
MEASURED AT ISO RO DRV
80
1.0
2.0
3.0
4.0
5.0
0
1.0
2.0
3.0
4.0
5.0
OUTPUT LOW VOLTAGE (V)
DIFFERENTIAL OUTPUT VOLTAGE (V)
_______________________________________________________________________________________
5
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