|
|
PDF MAX3291 Data sheet ( Hoja de datos )
| Número de pieza | MAX3291 | |
| Descripción | RS-485/RS-422 Transceivers with Preemphasis for High-Speed / Long-Distance Communication | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de MAX3291 (archivo pdf) en la parte inferior de esta página. Total 16 Páginas | ||
|
No Preview Available !
19-1405; Rev 1; 4/99
RS-485/RS-422 Transceivers with Preemphasis
for High-Speed, Long-Distance Communication
________________General Description
The MAX3291/MAX3292 high-speed RS-485/RS-422
transceivers feature driver preemphasis circuitry, which
extends the distance and increases the data rate of reli-
able communication by reducing intersymbol interfer-
ence (ISI) caused by long cables. The MAX3291 is
programmable for data rates of 5Mbps to 10Mbps,
while the MAX3292 is programmable for data rates up
to 10Mbps by using a single external resistor.
The MAX3291/MAX3292 are full-duplex devices that
operate from a single +5V supply and offer a low-cur-
rent shutdown mode that reduces supply current to
100nA. They feature driver output short-circuit current
limiting and a fail-safe receiver input that guarantees a
logic-high output if the input is open circuit. A 1/4-unit-
load receiver input impedance allows up to 128 trans-
ceivers on the bus.
________________________Applications
Long-Distance, High-Speed RS-485/RS-422
Communications
Telecommunications
Industrial-Control Local Area Networks
____________________________Features
o Preemphasis Increases the Distance and Data
Rate of Reliable RS-485/RS-422 Communication
o Data Rate
Optimized for 5Mbps to 10Mbps (MAX3291)
Programmable up to 10Mbps (MAX3292)
o 100nA Low-Current Shutdown Mode
o Allow Up to 128 Transceivers on the Bus
o -7V to +12V Common-Mode Input Voltage Range
o Pin-Compatible with ’75180, MAX489, MAX491
MAX3080, MAX3083, MAX3086, MAX1482
_______________Ordering Information
PART
MAX3291CSD
MAX3291CPD
MAX3291ESD
MAX3291EPD
MAX3292CSD
MAX3292CPD
MAX3292ESD
MAX3292EPD
TEMP. RANGE
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
14 SO
14 Plastic DIP
14 SO
14 Plastic DIP
14 SO
14 Plastic DIP
14 SO
14 Plastic DIP
Typical Operating Circuit and Functional Diagram
RPSET*
RPSET*
1µF
PEE
(PSET)
2
RO
3
RE
4
DE
DI 5
CPSET*
1 VCC 14
(VCCD)
A
13
12
B 11
Z 10
Y9
R = ZO
R = ZO
MAX3291
MAX3292
7(6) GND
1µF
R = ZO
R = ZO
PEE CPSET*
(PSET) 1
VCC 14
(VCCD)
9Y
10
Z
11 B
12
A
MAX3291
MAX3292
7(6) GND
13
5 DI
4 DE
3 RE
2
RO
( ) ARE FOR MAX3292
* MAX3292 ONLY
ZO = THE CHARACTERISTIC
IMPEDANCE OF THE CABLE
Pin Configuration appears at end of data sheet.
________________________________________________________________ Maxim Integrated Products 1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
1 page  
RS-485/RS-422 Transceivers with Preemphasis
for High-Speed, Long-Distance Communication
__________________________________________Typical Operating Characteristics
(VCC = +5V, TA = +25°C, unless otherwise noted.)
TYPICAL PREEMPHASIS WAVEFORM
VY - VZ
2V/
div
100ns/div
PREEMPHASIS INTERVAL vs. RPSET
(CPSET = 0.1µF)
2500
2250
2000
1750
1500
1250
NOTE A
1000
750
500
250
0
0 100 200 300 400 500 600 700 800 900 1000
RPSET (kΩ)
1200
1000
800
600
400
200
0
0
RPRE AND tPRE vs. tBAUD
NOTE A
500 1000 1500
tBAUD (ns)
2000
DRIVER DIFFERENTIAL
OUTPUT VOLTAGE vs. RDIFF
4.5
STRONG
4.0
DRIVER DIFFERENTIAL
OUTPUT VOLTAGE vs. TEMPERATURE
4.25
4.00 STRONG (VODP)
RECEIVER PROPAGATION DELAY
vs. TEMPERATURE
60.0
CL = 50pF
57.5
3.5
3.0 NORMAL
2.5
2.0
1.5
1.0
3.75
3.50
3.25
3.00
2.75
2.50 NORMAL (VOD)
55.0
52.5
50.0
47.5
45.0
0.5
0
10 20 30 40 50 60 70 80 90 100
2.25
RDIFF = 54Ω
2.00
-40 -20 0 20 40 60 80 100
42.5
40.0
-40 -20 0 20 40 60
RDIFF (Ω)
DRIVER PROPAGATION DELAY
TEMPERATURE (°C)
TEMPERATURE (°C)
vs. TEMPERATURE
RECEIVER PROPAGATION DELAY
50.0
CL1 = CL2 = 50pF
47.5
80 100
45.0
42.5
2.5V/
40.0
VA - VB
div
37.5 5V/
35.0 RO div
32.5
30.0
-40 -20
0 20 40 60
TEMPERATURE (°C)
80 100
20ns/div
Note A: Dotted line represents region in which preemphasis may not work in systems with excessive power-supply noise. See
Preemphasis at Low Data Rates.
_______________________________________________________________________________________ 5
5 Page 
RS-485/RS-422 Transceivers with Preemphasis
for High-Speed, Long-Distance Communication
Setting the Preemphasis Interval
The MAX3291 has an internal fixed preemphasis interval
of 100ns. Use the MAX3291 for existing designs requiring
industry-standard ’75180 pin-compatibility at data rates of
5Mbps to 10Mbps.
The MAX3292 has a resistor-programmable preemphasis
interval for more flexibility. For data rates less than 1Mbps,
use the following equation to calculate RPSET (the pre-
emphasis setting resistor):
RPSET = 580 (tBAUD - 100)
where tBAUD = one baud period in ns.
For example, a baud rate of 500kbps produces a baud
period of 2µs (2µs = 2000ns).
RPSET = 580 (tBAUD - 100)
RPSET = 580 (2000 - 100) = 1.1MΩ
For data rates of 1Mbps to 10Mbps, use the following
equation to calculate RPSET:
RPSET = 580 (tBAUD - 100)(tBAUD / 1000)
where tBAUD = one baud period in ns.
For example, a baud rate of 1Mbps produces a baud
period of 1µs (1µs = 1000ns).
RPSET = 580 (1000 - 100)(1000 / 1000) = 522kΩ
(closest standard value is 523kΩ)
Set the preemphasis interval by connecting the RPSET
resistor from PSET to VCC. Use a 0.1µF bypass capaci-
tor (CPSET) from PSET to VCC. If PSET is connected
directly to VCC (RPSET = 0), the preemphasis interval
reverts to the nominal 100ns value.
10,000
1000
24-GAUGE
TWISTED PAIR
10% JITTER
PREEMPHASIS
485 DRIVER
LIMIT
CONVENTIONAL
485 DRIVER
LIMIT
100
0.1
PREEMPHASIS REQUIRED
FOR ERROR-FREE
TRANSMISSION
1
DATA RATE (Mbps)
10
Eye Diagrams
One simple method to quickly determine your circuit
configuration is to view an eye diagram. An eye dia-
gram is a scope photo (voltage vs. time) showing the
transitions of a pseudo-random bit string displaying at
least one bit interval. Use an eye diagram to quickly
calculate the total jitter of a circuit configuration. Jitter is
the total time variation at the zero-volt differential cross-
ing, and percent jitter is expressed as a percentage of
one baud period, tBAUD. Figures 15 and 16 show typi-
cal eye diagrams for a non-preemphasis device and
the MAX3291/MAX3292. ISI and jitter are often used
interchangeably; however, they are not exactly the
same thing. ISI usually makes up the majority of the jit-
ter, but asymmetrical high and low driver output voltage
levels and time skews of non-ideal transceivers (driver
and receiver) also contribute to jitter.
Figure 15. Eye Diagram of a Typical RS-485 Transceiver
Without Preemphasis, while Driving 1000 feet of Cable at
5Mbps
Figure 14. Preemphasis Driver Performance Compared to a
Conventional Driver Without Preemphasis at 10% Jitter
Figure 16. Eye Diagram of the MAX3292 with a Preemphasis
Interval of 175ns, while Driving 1000 feet of Cable at 5Mbps
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet MAX3291.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| MAX329 | (MAX328 / MAX329) Ultra-Low Leakage Monolithic CMOS Analog Multiplexers |  Maxim Integrated Products |
| MAX3291 | RS-485/RS-422 Transceivers with Preemphasis for High-Speed / Long-Distance Communication | Maxim Integrated |
| MAX3293 | SOT23 RS-485 / RS-422 Transmitters | Maxim Integrated |
| MAX3293AUT-T | 20Mbps / +3.3V / SOT23 RS-485/ RS-422 Transmitters | Maxim Integrated |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |