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PDF MAX1490E Data sheet ( Hoja de datos )
| Número de pieza | MAX1490E | |
| Descripción | (MAX1480E / MAX1490E) Isolated RS-485/RS-422 | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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19-1940; Rev 0; 4/01
±15kV ESD-Protected, Isolated RS-485/RS-422
Data Interfaces
_________________General Description
The MAX1480EA/MAX1480EC/MAX1490EA/MAX1490EB
are complete, electrically isolated, RS-485/RS-422 data
communications interface solutions in a hybrid microcir-
cuit. The RS-485/RS-422 I/O pins are protected against
±15kV electrostatic discharge (ESD) shocks, without
latchup. Transceivers, optocouplers, and a transformer
provide a complete interface in a standard DIP package.
A single +5V supply on the logic side powers both sides
of the interface.
The MAX1480EC/MAX1490EB feature 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
MAX1480EA/MAX1490EA driver slew rate is not limited,
allowing transmission rates up to 2.5Mbps. The
MAX1480EA/MAX1480EC are designed for half-duplex
communication, while the MAX1490EA/MAX1490EB fea-
ture full-duplex communication.
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
featurewww.DataSheet4U.com that guarantees a known output (RO low for the
MAX1480EA/MAX1480EC, RO high for the MAX1490EA/
MAX1490EB) if the input is open circuit.
The MAX1480EA/MAX1480EC/MAX1490EA/MAX1490EB
withstand 1260VRMS (1min) or 1520VRMS (1s). Their iso-
lated outputs meet all RS-485/RS-422 specifications. The
MAX1480EA/MAX1480EC are available in a 28-pin DIP
package, and the MAX1490EA/MAX1490EB 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
Telecom
Selector Guide appears at end of data sheet.
____________________________Features
o Isolated Data Interface, Guaranteed to 1260VRMS
(1min)
o ±15kV ESD Protection on I/O Pins
o Slew-Rate Limited for Errorless Data
Transmission (MAX1480EC/MAX1490EB)
o High-Speed, Isolated, 2.5Mbps RS-485/RS-422
Interface (MAX1480EA/MAX1490EA)
o Full-Duplex Data Communication
(MAX1490EA/MAX1490EB)
o Single +5V Supply
o Current Limiting and Thermal Shutdown for
Driver Overload Protection
o Standard 0.6in DIP Packages
28-Pin DIP (MAX1480EA/MAX1480EC)
24-Pin DIP (MAX1490EA/MAX1490EB)
_______________Ordering Information
PART†
TEMP. RANGE PIN-PACKAGE
MAX1480EACPI 0°C to +70°C 28 Wide Plastic DIP*
MAX1480EAEPI -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 C parts is
up to 250kbps.
*See Reliability section at end of data sheet.
Pin Configurations
TOP VIEW
VCC1 1
VCC2 2
24 AC1 MAX1490EA/
MAX1490EB
23 AC2
D1 3
D2 4
22 ISO VCC1
21 ISO RO DRV
GND1 5
20 A
FS 6
19 B
SD 7
18 Z
VCC3 8
DI 9
17 Y
16 ISO COM1
VCC4 10
15 ISO DI DRV
RO 11
14 ISO VCC2
GND2 12
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/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1 page  
±15kV ESD-Protected, Isolated RS-485/RS-422
Data Interfaces
__________________________________________Typical Operating Characteristics
(VCC_ = +5V, VFS = VCC_, Figures 1 and 2, TA = +25°C, unless otherwise noted.)
OUTPUT CURRENT vs.
RECEIVER OUTPUT LOW VOLTAGE
80
MEASURED AT ISO RO DRV
70
60
50
40
30
20
10
0
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
OUTPUT LOW VOLTAGE (V)
RECEIVER OUTPUT LOW VOLTAGE
vs. TEMPERATURE
0.8
MEASURED AT ISO RO DRV
0.7 IRO = 8mA
0.6
0.5
0.4
0.3
0.2
0.1
0
-40
-20
0 20 40 60
TEMPERATURE (°C)
80
DRIVER OUTPUT CURRENT
vs. DIFFERENTIAL OUTPUT VOLTAGE
80
DI´ = HIGH OR OPEN
70
60
50
40
30
20
10
0
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
DIFFERENTIAL OUTPUT VOLTAGE (V)
OUTPUT CURRENT vs.
RECEIVER OUTPUT HIGH VOLTAGE
-30
MEASURED AT ISO RO DRV
-25
-20
-15
-10
-5
0
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
OUTPUT HIGH VOLTAGE (V)
OUTPUT CURRENT vs.
DRIVER OUTPUT LOW VOLTAGE
180
160
140
120
100
80
60
40
20
0
0 1 2 3 4 5 6 7 8 9 10 11 12
OUTPUT LOW VOLTAGE (V)
DRIVER DIFFERENTIAL OUTPUT VOLTAGE
vs. TEMPERATURE
3.0
2.9
DI´ = HIGH OR OPEN
RL = 54Ω
2.8
2.7
2.6
2.5
2.4
2.3
2.2
2.1
2.0
-40 -20
0 20 40 60
TEMPERATURE (°C)
80
RECEIVER OUTPUT HIGH VOLTAGE
vs. TEMPERATURE
5.00
MEASURED AT ISO RO DRV
4.75 IRO = 8mA
4.50
4.25
4.00
3.75
3.50
3.25
3.00
-40
-20
0 20 40 60
TEMPERATURE (°C)
80
OUTPUT CURRENT vs.
DRIVER OUTPUT HIGH VOLTAGE
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
-7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6
OUTPUT HIGH VOLTAGE (V)
SHUTDOWN CURRENT
vs. TEMPERATURE
0.40
SD = VCC_, DI´ = VCC_
0.35 DE´= VCC_(MAX1480EC ONLY)
MEASURED AT VCC1 AND VCC2
0.30
0.25
0.20
0.15
0.10
0.05
0
-40
-20
0 20 40 60
TEMPERATURE (°C)
80
_______________________________________________________________________________________ 5
5 Page 
±15kV ESD-Protected, Isolated RS-485/RS-422
Data Interfaces
VCC3
Q
FS
OSC
1.07MHz/
T F/F
1.45MHz
Q
MAX845
D1
N
D2 ISO RO DRV
N ISO DI DRV
SD GND1
R
MAX1490EA: MAX490E
MAX1490EB: MAX488E
D
A
B
Z
Y
VIN
+5V
C1 C2
22µF 0.1µF
74HC86
OR EQUIVALENT
DI DRIVER INPUT
R1*
DI´
RECEIVER OUTPUT R2*
RO
*SEE TABLE 2.
VCC1
VCC2
1
2
D1 3
MAX1490EA/
MAX1490EB
24 AC1 (MAKE NO CONNECTION)
23 AC2 (MAKE NO CONNECTION)
22 ISO VCC1
EXTERNAL RS-485/RS-422 WIRING
TERMINATING RESISTOR
(ONE RESISTOR ON EACH END)
TWISTED PAIR
TO OTHER TRANSCEIVERS
D2 4
21 ISO RO DRV
RL
GND1 5
FS 6
20 A
19 B
A
B SHIELD (OPTIONAL)
SD 7
VCC3 8
DI 9
VCC4 10
18 Z
17 Y
16 ISO COM1
15 ISO DI DRV
Z RL
Y
TWISTED PAIR
TO OTHER TRANSCEIVERS
R5, 100Ω SH1
R4* SH2
SHIELD (OPTIONAL)
R0 11
GND2 12
14 ISO VCC2
13 ISO RO LED
R3*
ISOLATION BARRIER
R6, 100Ω
ISOLATED COMMON
NOTE: RESISTORS R5 AND R6 PROTECT
THE MAX1490EA/MAX1490EB FROM
TRANSIENT CURRENTS BETWEEN SHIELD AND
TRANSMISSION LINES.
LOGIC GROUND 270 pF
4kV
Figure 2. MAX1490EA/MAX1490EB Detailed Block Diagram and Typical Application Circuit
RL
RL
Table 2. Pullup and LED Drive Resistors for Figure 2
PART
MAX1490EA
MAX1490EB
R1 (Ω)
200
200
R2 (Ω)
1000
3000
R3 (Ω)
330
330
R4 (Ω)
1000
3000
MAX1480EC/MAX1490EB:
Reduced EMI and Reflections
The MAX1480EC/MAX1490EB are slew-rate-limited,
minimizing EMI and reducing reflections caused by
improperly terminated cables. Figure 11 shows both
the driver output waveform of a MAX1480EA/
MAX1490EA transmitting a 150kHz signal and the
Fourier analysis of that waveform. High-frequency har-
monics with large amplitudes are evident. Figure 12
shows the same information for the slew-rate-limited
MAX1480EC/MAX1490EB transmitting the same signal.
The high-frequency harmonics have much lower ampli-
tudes, and therefore the potential for EMI is significantly
reduced.
Driver Output Protection
There are two mechanisms to prevent excessive output
current and power dissipation caused by faults or by
bus contention. A foldback current limit on the output
stage provides immediate protection against short cir-
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 19 Páginas | |
| PDF Descargar | [ Datasheet MAX1490E.PDF ] | |
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