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PDF MAX3491 Data sheet ( Hoja de datos )
| Número de pieza | MAX3491 | |
| Descripción | 3.3V-Powered / 10Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de MAX3491 (archivo pdf) en la parte inferior de esta página. Total 17 Páginas | ||
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AVAILABLE
MAX3483/MAX3485/MAX3486/
MAX3488/MAX3490/MAX3491
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
_______________General Description ____________________________Features
The MAX3483, MAX3485, MAX3486, MAX3488,
MAX3490, and MAX3491 are 3.3V, low-power trans-
ceivers for RS-485 and RS-422 communication. Each
part contains one driver and one receiver. The
MAX3483 and MAX3488 feature slew-rate-limited dri-
vers that minimize EMI and reduce reflections caused
by improperly terminated cables, allowing error-free
data transmission at data rates up to 250kbps. The par-
tially slew-rate-limited MAX3486 transmits up to
2.5Mbps. The MAX3485, MAX3490, and MAX3491
transmit at up to 10Mbps.
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 both
inputs are open circuit.
The MAX3488, MAX3490, and MAX3491 feature full-
duplex communication, while the MAX3483, MAX3485,
and MAX3486 are designed for half-duplex communi-
cation.
________________________Applications
Low-Power RS-485/RS-422 Transceivers
Telecommunications
Transceivers for EMI-Sensitive Applications
Industrial-Control Local Area Networks
Functional Diagrams
o Operate from a Single 3.3V Supply—
No Charge Pump!
o Interoperable with +5V Logic
o 8ns Max Skew (MAX3485/MAX3490/MAX3491)
o Slew-Rate Limited for Errorless Data Transmission
(MAX3483/MAX3488)
o 2nA Low-Current Shutdown Mode
(MAX3483/MAX3485/MAX3486/MAX3491)
o -7V to +12V Common-Mode Input Voltage Range
o Allows up to 32 Transceivers on the Bus
o Full-Duplex and Half-Duplex Versions Available
o Industry Standard 75176 Pinout
(MAX3483/MAX3485/MAX3486)
o Current-Limiting and Thermal Shutdown for
Driver Overload Protection
______________Ordering Information
PART
TEMP. RANGE PIN-PACKAGE
MAX3483CPA
0°C to +70°C
8 Plastic DIP
MAX3483CSA
0°C to +70°C
8 SO
MAX3483C/D
0°C to +70°C
Dice*
MAX3483EPA
-40°C to +85°C
8 Plastic DIP
MAX3483ESA
-40°C to +85°C
8 SO
MAX3485CPA
0°C to +70°C
8 Plastic DIP
MAX3485CSA
0°C to +70°C
8 SO
MAX3485C/D
0°C to +70°C
Dice*
MAX3485EPA
-40°C to +85°C
8 Plastic DIP
MAX3485ESA
-40°C to +85°C
8 SO
Ordering Information continued at end of data sheet.
* Contact factory for for dice specifications.
______________________________________________________________Selection Table
PART
NUMBER
GUARANTEED
DATA RATE
(Mbps)
SUPPLY
VOLTAGE
(V)
HALF/FULL
DUPLEX
MAX3483
0.25
Half
MAX3485
10
Half
MAX3486
2.5
PinMCAoXn3fi4g8u8rations ap0p.e2a5r at end of3d.0attao s3h.6eet.
Half
Full
FunMcAtiXon3a4l9D0iagrams c1o0ntinued at end of data sheet. Full
UCMSPAiXs3a4t9ra1demark of M10axim Integrated Products, Inc. Full
SLEW-RATE
LIMITED
Yes
No
Yes
Yes
No
No
DRIVER/
RECEIVER
ENABLE
Yes
Yes
Yes
No
No
Yes
SHUTDOWN
CURRENT
(nA)
2
2
2
—
—
2
PIN
COUNT
8
8
8
8
8
14
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
19-0333; Rev 0; 12/94
1 page  
MAX3483/MAX3485/MAX3486/
MAX3488/MAX3490/MAX3491
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
__________________________________________Typical Operating Characteristics
(VCC = 3.3V, TA = +25°C, unless otherwise noted.)
OUTPUT CURRENT vs.
RECEIVER OUTPUT LOW VOLTAGE
25
20
15
10
5
0
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
OUTPUT LOW VOLTAGE (V)
OUTPUT CURRENT vs.
RECEIVER OUTPUT HIGH VOLTAGE
-20
-18
-16
-14
-12
-10
-8
-6
-4
-2
0
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
OUTPUT HIGH VOLTAGE (V)
RECEIVER OUTPUT HIGH VOLTAGE
vs. TEMPERATURE
3.30 IRO = 1.5mA
3.25
3.20
3.15
3.10
3.05
3.00
-40 -20
0 20 40 60
TEMPERATURE (°C)
80 100
RECEIVER OUTPUT LOW VOLTAGE
vs. TEMPERATURE
0.8
IRO = 2.5mA
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
-40 -20
0 20 40 60
TEMPERATURE (°C)
80 100
DRIVER OUTPUT CURRENT vs.
DIFFERENTIAL OUTPUT VOLTAGE
100
90
80
70
60
50
40
30
20
10
0
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
DIFFERENTIAL OUTPUT VOLTAGE (V)
DRIVER DIFFERENTIAL OUTPUT
VOLTAGE vs.TEMPERATURE
2.6
2.5
R = 54Ω
2.4
2.3
2.2
2.1
2.0
1.9
1.8
1.7
1.6
-40 -20
0 20 40 60
TEMPERATURE (°C)
80 100
OUTPUT CURRENT vs.
DRIVER OUTPUT LOW VOLTAGE
175
OUTPUT CURRENT vs.
DRIVER OUTPUT HIGH VOLTAGE
-100
150 -80
125
100 -60
75
50
25
0
0
2 4 6 8 10
OUTPUT LOW VOLTAGE (V)
12
-40
-20
0
-7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5
OUTPUT HIGH VOLTAGE (V)
Maxim Integrated
5
5 Page 
MAX3483/MAX3485/MAX3486/
MAX3488/MAX3490/MAX3491
3.3V-Powered, 10Mbps and Slew-Rate-Limited
True RS-485/RS-422 Transceivers
____________________Function Tables
Devices with Receiver/Driver Enable
(MAX3483/MAX3485/MAX3486/MAX3491)
Table 1. Transmitting
INPUTS
RE DE DI
OUTPUTS
B* A*
MODE
X11
0
1 Normal
X10
1
0 Normal
0 0 X High-Z High-Z Normal
1 0 X High-Z High-Z Shutdown
* B and A outputs are Z and Y, respectively, for full-duplex part
(MAX3491).
X = Don’t care; High-Z = High impedance
Table 2. Receiving
INPUTS
RE DE
A, B
0 0*
≥ +0.2V
OUTPUTS
RO
1
MODE
Normal
0 0*
≤ -0.2V
0
Normal
0 0* Inputs Open
10
X
1
High-Z
Normal
Shutdown
* DE is a “don’t care” (x) for the full-duplex part (MAX3491).
X = Don’t care; High-Z = High impedance
Devices without Receiver/Driver Enable
(MAX3488/MAX3490)
Table 3. Transmitting
INPUT
OUTPUTS
DI Z Y
1 01
0 10
Table 4. Receiving
INPUTS
OUTPUT
A, B RO
≥ +0.2V
1
≤ -0.2V
0
Inputs Open
1
__________Applications Information
The MAX3483/MAX3485/MAX3486/MAX3488/MAX3490/
MAX3491 are low-power transceivers for RS-485 and
RS-422 communications. The MAX3483 and MAX3488
can transmit and receive at data rates up to 250kbps,
the MAX3486 at up to 2.5Mbps, and the MAX3485/
MAX3490/MAX3491 at up to 10Mbps. The MAX3488/
MAX3490/MAX3491 are full-duplex transceivers, while
the MAX3483/MAX3485/MAX3486 are half-duplex.
Driver Enable (DE) and Receiver Enable (RE) pins are
included on the MAX3483/MAX3485/MAX3486/
MAX3491. When disabled, the driver and receiver out-
puts are high impedance.
Reduced EMI and Reflections
(MAX3483/MAX3486/MAX3488)
The MAX3483/MAX3488 are slew-rate limited, minimiz-
ing EMI and reducing reflections caused by improperly
terminated cables. Figure 13 shows both the driver
output waveform of a MAX3485/MAX3490/MAX3491
transmitting a 125kHz signal and the Fourier analysis of
that waveform. High-frequency harmonics with large
amplitudes are evident. Figure 14 shows the same infor-
mation, but for the slew-rate-limited MAX3483/MAX3488
transmitting the same signal. The high-frequency har-
monics have much lower amplitudes, and the potential for
EMI is significantly reduced.
Low-Power Shutdown Mode
(MAX3483/MAX3485/MAX3486/MAX3491)
A low-power shutdown mode is initiated by bringing both
RE high and DE low. The devices will not shut down
unless both the driver and receiver are disabled (high
impedance). In shutdown, the devices typically draw
only 2nA of supply current.
For these devices, the tPSH and tPSL enable times
assume the part was in the low-power shutdown mode;
the tPZH and tPZL enable times assume the receiver or
driver was disabled, but the part was not shut down.
10dB/div
10dB/div
0Hz
500kHz/div
5MHz
Figure 13. Driver Output Waveform and FFT Plot of MAX3485/
MAX3490/MAX3491 Transmitting a 125kHz Signal
0Hz
500kHz/div
5MHz
Figure 14. Driver Output Waveform and FFT Plot of MAX3483/
MAX3488 Transmitting a 125kHz Signal
Maxim Integrated
11
11 Page | ||
| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet MAX3491.PDF ] | |
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