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MAX487CPA+中文资料
19-0122; Rev 8; 10/03
Low-Power, Slew-Rate-LimitedRS-485/RS-422 Transceivers
General Description
__Next Generation Device Features
The MAX481, MAX483, MAX485, MAX487–MAX491, andMAX1487 are low-power transceivers
for RS-485 and RS-?For Fault-Tolerant Applications
422
communication.
Each
part
contains
one
driver
and
oneMAX3430:
±80V
Fault-Protected, Fail-Safe, 1/4receiver. The MAX483, MAX487, MAX488, and MAX489Unit
Load,
3.3V, RS-485 Transceiver
feature reduced slew-rate drivers that minimize EMI andMAX3440E–MAX3444E: ±15kV
ESD-Protected,reduce reflections caused by improperly terminated cables,±60V
Fault-Protected, 10Mbps, Fail-Safe, thus allowing error-free data transmission up
to 250kbps.The driver slew rates of the MAX481, MAX485, MAX490,RS-485/J1708
Transceivers
MAX491, and MAX1487 are not limited, allowing them to?For Space-Constrained
Applications
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transmit up to 2.5Mbps.
MAX3460–MAX3464:
5V,
Fail-Sahttp://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92fe,
20Mbps,These
transceivers draw between 120?A and 500?A ofProfibus RS-485/RS-422 Transceivers
supply current when unloaded or fully loaded with disabledMAX3362:
3.3V, High-Speed,
RS-485/RS-422drivers. Additionally, the MAX481, MAX483, and MAX487Transceiver in a
SOT23 Package
have a low-current shutdown mode in which they consumeMAX3280E–MAX3284E: ±15kV
ESD-Protected,only 0.1?A. All parts operate from a single 5V supply.
52Mbps,
3V to
5.5V, SOT23, RS-485/RS-422,Drivers are short-circuit current
limited and are protectedTrue Fail-Safe Receivers
against excessive power dissipation by thermal shutdowncircuitry that places the
driver outputs into a high-imped-MAX3293/MAX3294/MAX3295: 20Mbps,
The
receiver
input
has
a
fail-safe
feature
3.3V,ance state.
thatSOT23,
RS-855/RS-422
Transmittersguarantees a logic-high output if the input is open circuit.?For Multiple
Transceiver Applications
Thttp://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92he
feature quarter-unit-loadMAX3030E–MAX3033E:
MAX487
and
MAX1487
±15kV ESD-Protected,receiver input
impedance, allowing up to 128 MAX487/ 3.3V, Quad RS-422 TransmittersMAX1487
transceivers on the bus. Full-duplex communi-?For Fail-Safe Applications
cations are obtained using the MAX488–MAX491, whilethe MAX481, MAX483, MAX485,
MAX487,
and
MAX1487MAX3080–MAX3089:
half-duplex applications.
Fail-Safe,
High-Speedare
designed
for
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(10Mbps), Slew-Rate-Limited RS-485/RS-422Transceivers
________________________Applications
?For Low-Voltage Applications
Low-Power RS-485 TransceiversMAX3483E/MAX3485E/MAX3486E/MAX3488E/Low-Power RS-422
TransceiversMAX3490E/MAX3491E:
3.3V Powered, ±15kVLevel Translators
ESD-Protected, 12Mbps, Slew-Rate-Limited,True RS-485/RS-422 Transceivers
Transceivers for EMI-Sensitive ApplicationsIndustrial-Control Local Area Networks
Ordering
Informahttp://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92tion
appears at end of data sheet.
______________________________________________________________Selection Table
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.
MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487
Low-Power,
Slew-Rate-LimitedRS-485/RS-422
TransceiversMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487
ABSOLUTE MAXIMUM RATINGS
Supply
Voltage
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(VCC).............................................................12VControl
Input Voltage (RE, DE)...................-0.5V to (VCC
(DI).............................-0.5V to (VCC
B)...................................-8V to
B).................................-8V
(RO).....................-0.5V
0.5V)Driver Input Voltage
0.5V)Driver Output Voltage (A,
12.5VReceiver Input Voltage (A,
to
12.5VReceiver
to
(VCC
Output
0.5V)Continuous
Dihttp://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92ssipation (TA=
8-Pin Plastic DIP (derate 9.09mW/°C above
(derate 10.00mW/°C above
Voltage
Power
70°C)
70°C)....727mW14-Pin Plastic DIP
70°C)..800mW8-Pin SO (derate 5.88mW/°C above
70°C).................471mW
14-Pin SO (derate 8.33mW/°C above
4.1mW/°C above
70°C)...............667mW8-Pin ?MAX (derate
70°C)..............830mW8-Pin CERDIP (derate 8.00mW/°C above
70°C).........640mW14-Pin
CERDIP
(derate
9.09mW/°C
above
70°C).......727mWOperating Temperature Ranges
MAX4_ _C_ _/MAX1487C_ A...............................0°C to
_/MAX1487E_
A.............................-40°C
85°CMAX4__MJ_/MAX1487MJA...........................-55°C
Temperature Range.............................-65°C to
to
70°CMAX4__E_
to
125°CStorage
160°CLead Temperature
(soldering, 10sec)............................. 300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent
damage
to
the
device.
These
are
strhttp://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92ess ratings only, and
functionaloperation of the device at these or any other conditions beyond those
indicated in the operational sections of the specifications is not implied. Exposure
toabsolute maximum rating conditions for extended periods may affect device
reliability.
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DC ELECTRICAL CHARACTERISTICS
(VCC= 5V ±5%, TA= TMINto TMAX, unless otherwise noted.) (Notes 1, 2)
PARAMETER
Differential Driver Output (no load)Differential Driver Output(with load)
Change in Magnitude of DriverDifferential Output Voltage forComplementary Output
StatesDriver Common-Mode OutputVoltage
Change in Magnitude of DriverCommon-Mode Output Voltagefor Complementary Output
StatesInput High VoltageInput Low VoltageInput Current
SYMBOLVOD1VOD2?VODVOC?VODVIHVILIIN1
R = 50?(RS-422)
R = 27?(RS-485), Figure 4R = 27?or 50?, Figure 4R = 27?or 50?, Figure 4R = 27?or 50?,
Figure 4DE, http://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92DI, REDE, DI,
REDE, DI, REDE = 0V;
VCC= 0V or 5.25V,all devices exceptMAX487/MAX1487
MAX487/MAX1487,
DE = 0V, VCC= 0V or 5.25V
Receiver Differential ThresholdVoltage
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Receiver
Input
HysteresisReceiver
Output
High
VoltageReceiver
VoltageThree-State (high impedance)Output Current at Receiver
VTH?VTHVOHVOLIOZR
-7V ≤VCM≤12VVCM= 0V
IO= -4mA, VID= 200mVIO = 4mA, VID= -200mV0.4V ≤VO≤2.4V
-7V ≤VCM≤12V, all devices exceptMAX487/MAX1487
-7V ≤VCM ≤12V, MAX487/MAX1487
12483.5
0.4±1
VIN= 12VVIN= -7VVIN= 12VVIN= -7V
-0.2
70
2.0
0.8±21.0
mA
Output
Low
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-0.80.25-0.20.2
mAVmVVV?Ak?k?
21.5
50.230.2
CONDITIONS
MIN
TYP
MAX5
UNITSVVVVVVV?A
Input Current(A, B)
IIN2
Receiver
Input
Resistancehttp://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92RIN
2_______________________________________________________________________________
________
Low-Power, Slew-Rate-LimitedRS-485/RS-422 Transceivers
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DC ELECTRICAL CHARACTERISTICS (continued)
(VCC= 5V ±5%, TA= TMINto TMAX, unless otherwise noted.) (Notes 1, 2)
SWITCHING CHARACTERISTICS—MAX481/MAX485, MAX490/MAX491, MAX1487
(VCC= 5V ±5%, TA= TMINto TMAX, unless otherwise noted.) (Notes 1, 2)
PARAMETER
SYMBOLCONDITIONSMINTYPMAXUNITSDriver Input to OutputtPLHFigures 6 and 8, RDIFF= 54?,
103060tPHL
CL1= CL2= 100pF103060nsDriver Output Skew to OutputtSKEWFigures 6 and 8, RDIFF= 54?,
CL1= CL2= 100pF510nsFigures 6 and 8,
MAX481, MAX485, MAX148731540Driver Rise or Fall TimetR, tFRDIFF= 54?,MAX490C/E,
MAX491C/E51525nsCL1= CL2= 100pFMAX490M, MAX491M
3
1540Driver
Enable
to
Output
HightZHFigures
7
and
9,
CL=
100pF,
S2
closed4070nshttp://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92Driver Enable
to Output LowtZLFigures 7 and 9, CL= 100pF, S1 closed4070nsDriver Disable Time from
LowtLZFigures 7 and 9, CL= 15pF, S1 closed4070nsDriver Disable Time from
HightHZFigures 7 and 9, CL= 15pF, S2 closed
4070nsFigures 6 and 10,MAX481, MAX485, MAX1487
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2090200Receiver Input to Output
tPLH, tPHLRDIFF= 54?,MAX490C/E, MAX491C/E
2090150ns
CL1= CL2= 100pFMAX490M, MAX491M20
90200
|tPLH- tPHL|Differential
Receiver Skew
tSKDFigures 6 and 10, RDIFF= 54?,CL1= CL2= 100pF
13nsReceiver
Enable
to
Output
LowtZLFigures
5
and
11,
CRL=
15pF,
S1
closed2050nsReceiver Enable to Output HightZHFigures 5 and 11, CRL= 15pF, S2
closed2050nsReceiver Disable Time from LowtLZFigures 5 and 11, CRL= 15pF, S1
closed2050nsReceiver Disable Time from HightHZFigures 5 and 11, CRL= 15pF, S2 closed
2050nsMaximum Data RatefMAX2.5MbpsTime to Shutdown
tSHDNhttp://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92
MAX481 (Note 5)
50200
600ns
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________________________________________________________________________________
_______3
MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487
Low-Power,
Slew-Rate-LimitedRS-485/RS-422
TransceiversMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487
SWITCHING CHARACTERISTICS—MAX481/MAX485, MAX490/MAX491, MAX1487 (continued)
(VCC= 5V ±5%, TA= TMINto TMAX, unless otherwise noted.) (Notes 1, 2)
PARAMETER
SYMBOL
CONDITIONS
Figures 7 and 9, CL= 100pF, S2 closedFigures 7 and 9, CL= 100pF, S1 closedFigures
5 and 11, CL= 15pF, S2 closed,A - B = 2V
Figures 5 and 11, CL= 15pF, S1 closed,B - A = 2V
MIN
TYP4040300300
MAX10010010001000
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UNITSnsnsnsns
Driver Enable from Shutdown to
tZH(SHDN)
Output High (MAX481)
Driver Enable from Shutdown to
thttp://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92ZL(SHDN)
Output Low (MAX481)
Receiver Enable from Shutdown
tZH(SHDN)
to Output High (MAX481)
Receiver Enable from Shutdown
tZL(SHDN)
to Output Low (MAX481)
SWITCHING CHARACTERISTICS—MAX483, MAX487/MAX488/MAX489
(VCC= 5V ±5%, TA= TMINto TMAX, unless otherwise noted.) (Notes 1, 2)
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PARAMETER
Driver Input to OutputDriver Output Skew to OutputDriver Rise or Fall TimeDriver
Enable to Output HighDriver Enable to Output LowDriver Disable Time from LowDriver
Disable Time from HighReceiver Input to Output
SYMBOLtPLHtPHLtSKEWtR,
tFtZHtZLtLZtHZtPLHtPHLtSKDtZLtZHtLZtHZfMAXtSHDNtZH(SHDN)tZL(SHDN)tZH(SHDN)tZL(SH
DN)
CONDITIONS
Figures 6 and 8, RDIFF= 54?,CL1= CL2= 100pF
Figures 6 and 8, RDIFF= 54?,CL1= CL2= 100pF
Figures 6 and 8, RDIFF= 54?,CL1= CL2= 100pF
Figures
7
and
9,
CL=
100pF,
S2
closedFiguhttp://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92res 7 and 9, CL=
100pF, S1 closedFigures 7 and 9, CL= 15pF, S1 closedFigures 7 and 9, CL= 15pF, S2
closedFigures 6 and 10, RDIFF= 54?,CL1= CL2= 100pF
Figures 6 and 10, RDIFF= 54?,CL1= CL2= 100pF
Figures 5 and 11, CRL= 15pF, S1 closedFigures 5 and 11, CRL= 15pF, S2 closedFigures
5 and 11, CRL= 15pF, S1 closedFigures 5 and 11, CRL= 15pF, S2 closedtPLH, tPHL
MAX483/MAX487, Figures 7 and 9,CL= 100pF, S1 closed
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MAX483/MAX487, Figures 5 and 11,CL= 15pF, S2 closed
MAX483/MAX487, Figures 5 and 11,CL= 15pF, S1 closed
25050
200
6002000200025002500
250250250300300250250
10020202020
50505050
MIN250250
TYP800800100
MAX200020008002000200020003000300020002000
UNITSnsnsnsnsnsnsnsnsnsnsnsnsnskbpsnsnsnsnsns
ItPLH- tPHLIDifferential
Receiver Skew
Receiver
Enable
to
Output
LowReceiver
http://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92to
Output
Enable
HighReceiver
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Disable Time from LowReceiver Disable Time from HighMaximum Data RateTime to Shutdown
Driver Enable from Shutdown toOutput High
Driver Enable from Shutdown toOutput Low
Receiver Enable from Shutdownto Output High
Receiver Enable from Shutdownto Output Low
4_______________________________________________________________________________
________
Low-Power, Slew-Rate-LimitedRS-485/RS-422 Transceivers
NOTES FOR ELECTRICAL/SWITCHING CHARACTERISTICS
Note 1:All currents into device pins are positive; all currents out of device pins
are negative. All voltages are referenced to device
ground unless otherwise specified.
Note 2:All typical specifications are given for VCC= 5V and TA=
25°C.
Note 3:Supply current specification is valid for loaded transmitters when DE = 0V.Note
4:Applies
to
peak
current.
See
Typical
Operatinghttp://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92
Characteristics.
Note 5:The MAX481/MAX483/MAX487 are put into shutdown by bringingREhigh and DE low.
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If the inputs are in this state for less
than 50ns, the parts are guaranteed not to enter shutdown. If the inputs are in this
state for at least 600ns, the parts areguaranteed to have entered shutdown. See
Low-Power Shutdown Modesection.
__________________________________________Typical Operating Characteristics
(VCC= 5V, TA =
25°C, unless otherwise noted.)
OUTPUT CURRENT vs.
OUTPUT CURRENT vs.
RECEIVER OUTPUT HIGH VOLTAGE vs.
RECEIVER OUTPUT LOW VOLTAGE
RECEIVER OUTPUT HIGH VOLTAGE
TEMPERATURE
451
-202
00-4.8
-18148X-18440AXMAM4.6)
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)
)
-16VA35A( 4.4mmE((G
-14T30TANNT4.2EE-12LRROR25RV 4.0UU-10HCCG
T15TUUUP3.6OT10O-6-4UO3.45-23.200
3.0
http://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92
0.5
1.0
1.5
2.0
2.51.52.02.53.03.54.04.55.0-50-250255075100125
OUTPUT LOW VOLTAGE (V)OUTPUT HIGH VOLTAGE (V)TEMPERATURE (°C)
RECEIVER OUTPUT LOW VOLTAGE vs.
DRIVER OUTPUT CURRENT vs.DRIVER DIFFERENTIAL OUTPUT VOLTAGE
TEMPERATURE
IT20TH3.8UU-8 PPT
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DIFFERENTIAL OUTPUT VOLTAGE
vs. TEMPERATURE
0.9905
2.4
0-10.88480X)
AMV(2.3 )
EVG()
A 0.7EA70T2.2GmLA( OT0.6TV2.1
LN60OETVRUP2.0 0.5WR50UTOCUL0.4 O
T40T
L1.9UUPAIP0.3T30TTN1.8UUEO0.2O20RE1.7FF0.110ID1.600
1.5
-50
-25
25
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50
75
10012500.51.01.52.02.53.03.54.04.5-50
-25
25
50
75
100
125
TEMPERATURE (°C)DIFFERENTIAL OUTPUT VOLTAGE (V)
TEMPERATURE (°C)
_________________________http://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92
______________________________________________________________5
MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487
Low-Power,
Slew-Rate-LimitedRS-485/RS-422
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TransceiversMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487
____________________________Typical Operating Characteristics (continued)
(VCC= 5V, TA =
25°C, unless otherwise noted.)
OUTPUT CURRENT vs.DRIVER OUTPUT LOW VOLTAGE
MAX481-07
OUTPUT CURRENT vs.DRIVER OUTPUT HIGH VOLTAGE
MAX481-08
MAX481/MAX485/MAX490/MAX491SUPPLY CURRENT vs. TEMPERATURE
140120OUTPUT CURRENT (mA)1008060402000
2
4
6
8
10
-120-100OUTPUT CURRENT (mA)
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-80-60-40-200
600500SUPPLY CURRENT (?A)400300
2001000
12-7-6-5-4-3-2-1012345-50-250255075100125
OUTPUT LOW VOLTAGE (V)OUTPUT HIGH VOLTAGE (V)TEMPERATURE (°C)
MAX483/MAX487–MAX48http://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b929
SUPPLY CURRENT vs. TEMPERATURE
MAX1487
SUPPLY CURRENT vs. TEMPERATURE
600500SUPPLY CURRENT (?A)400300
600500SUPPLY CURRENT (?A)400300
200100
200100
0-50
-25
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25
50
75
100
125
TEMPERATURE (°C)
-60-40-20
02040
6080100120140
TEMPERATURE (°C)
6_______________________________________________________________________________
________
Low-Power, Slew-Rate-LimitedRS-485/RS-422 Transceivers
______________________________________________________________Pin Description
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Figure 1. MAX481/MAX483/MAX485/MAX487/MAX1487 Pin Configuration and Typical
Operating Circuit
________________________________________________________________________________
_______
7
MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487://www.wendangwang.com/doc/eeec96abb6
ebb3bc58160b92par
Low-Power,
Slew-Rate-LimitedRS-485/RS-422
TransceiversMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487
Figure 2. MAX488/MAX490 Pin Configuration and Typical Operating Circuit
Figure 3. MAX489/MAX491 Pin Configuration and Typical Operating Circuit
__________Applications Information
The MAX481/MAX483/MAX485/MAX487–MAX491 andMAX1487 are low-power transceivers for
RS-485 and RS-422 communications. The MAX481, MAX485, MAX490,MAX491, and MAX1487 can
transmit and receive at datarates up to 2.5Mbps, while the MAX483, MAX487,MAX488,
and MAX489 are specified for data rates up to250kbps. The MAX488–MAX491 are
full-duplex trans-ceivers while the MAX481, MAX483, MAX485, MAX487,and MAX1487 are
half-duplex. In addition, Driver EnableMAX481, MAX483, MAX485, MAX487, MAX489,MAX491,
and MAX1487. When disabled, the driver andreceiver outputs are high impedance.
8
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MAX487/MAX1487:
128 Trahttp://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92nsceivers on the Bus
The 48k?, 1/4-unit-load receiver input impedance of theMAX487 and MAX1487 allows up
to 128 transceiverson a bus, compared to the 1-unit load (12k?inputimpedance) of
standard
RS-485
drivers
(32
trans-ceivers
maximum).
Any
combination
of
MAX487/MAX1487 and other RS-485 transceivers with a total of32 unit loads or less
can be put on the bus. TheMAX481/MAX483/MAX485 and MAX488–MAX491 havestandard
12k?Receiver Input impedance.
________________________________________________________________________________
_______
Low-Power, Slew-Rate-LimitedRS-485/RS-422 Transceivers
_________________________________________________________________Test Circuits
Figure 4. Driver DC Test LoadFigure 5. Receiver Timing Test Load
Figure 6. Driver/Receiver Timing Test CircuitFigure 7. Driver Timing Test Load
MAX483/MAX487/MAX488/MAX489:
monics
with
large
arhttp://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92e
amplitudes
evident.
Figure
13Reduced EMI and Reflections
shows the same information displayed for a MAX483,The MAX483 and MAX487–MAX489 are
slew-rate limit-MAX487, MAX488, or MAX489 transmitting under theed, minimizing EMI
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and reducing reflections caused bysame conditions. Figure 13’s high-frequency
harmonicsimproperly terminated cables. Figure 12 shows the dri-have much lower
amplitudes, and the potential for EMIver output waveform and its Fourier analysis
of ais significantly reduced.
150kHz signal transmitted by a MAX481, MAX485,MAX490, MAX491, or MAX1487.
High-frequency har-
________________________________________________________________________________
_______9
MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487
Low-Power,
Slew-Rate-LimitedRS-485/RS-422
TransceiversMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487
_______________________________________________________Switching Waveforms
Fhttp://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92igure
8.
Propagation Delays
Figure 9. Driver Enable and Disable Times (except MAX488 andMAX490)
Figure 10. Receiver Propagation Delays
Figure 11. Receiver Enable and Disable Times (except MAX488and MAX490)
_________________Function Tables (MAX481/MAX483/MAX485/MAX487/MAX1487)
Table 1. Transmitting
Driver
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Table 2. Receiving
10
Low-Power, Slew-Rate-LimitedRS-485/RS-422 Transceivers
10dB/div
10dB/div
0Hz
5MHz
0Hz
5MHz
500kHz/div
500kHz/div
Figure 12. Driver Output Waveform and FFT Plot of MAX481/Figure 13. Driver Output
Waveform and FFT Plot of MAX483/MAX485/MAX490/MAX491/MAX1487 Transmitting a
150kHzMAX487–MAX489 Transmitting a 150kHz Signal
Signal
Low-Power Shutdown ModeDriver Output Protection
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(MAX481/MAX483/MAX487)
Excessive
output
current
and
phttp://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92ower dissipation causedA
low-power shutdown mode is initiated by bringingby faults or by bus contention are
prevented by twoboth REhigh and DE low. The devices will not shutmechanisms. A
foldback current limit on the outputdown unless both the driver and receiver are
disabled.stage provides immediate protection against short cir-In shutdown, the
devices typically draw only 0.1?A ofcuits over the whole common-mode voltage range
(seesupply current.
Typical Operating Characteristics). In addition, a ther-REand DE may be driven
simultaneously; the parts aremal shutdown circuit forces the driver outputs into
aguaranteed not to enter shutdown if REis high and DEhigh-impedance state if the die
temperature risesis low for less than 50ns. If the inputs are in this
stateexcessively.
for at least 600ns, the parts are guaranteed to entershutdown.
Propagation Delay
Many
digital
encoding
schemes
depend
http://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92differ-For
MAX483,
and
MAX487,
the
tZHandence
between
the
driver
on
the
the
MAX481,
and
receiver
propagationtZLenable times assume the part was not in the low-delay times. Typical
propagation
delays
are
shown
inpower
shutdown
state
(the
MAX485/MAX488–MAX491Figures 15–18 using Figure 14’s test circuit.
and MAX1487 can not be shut down). The tand tZH(SHDN)ZL(SHDN)enable times assume the
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parts were shutThe difference in receiver delay times, | tPLH- tdown (see Electrical
Characteristics).
typically under 13ns for the MAX481, MAX485,PHL|, isMAX490, MAX491, and MAX1487 and
is typically lessIt takes the drivers and receivers longer to becomethan 100ns for
the MAX483 and MAX487–MAX489.enabled from the low-power shutdown state(tThe driver
skew times are typically 5ns (10ns max) for(tZH(SHDN), tZL(SHDN)) than from the
operating modeZH, tZL). (The parts are in operating mode if the –R—E–,the MAX481,
MAX485,
MAX490,
MAX491,
andDE
ihttp://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92nputs equal a logical 0,1
or 1,1 or 0, 0.)
MAX1487, and are typically 100ns (800ns max) for theMAX483 and MAX487–MAX489.
________________________________________________________________________________
______11
MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487
Low-Power,
Slew-Rate-LimitedRS-485/RS-422
TransceiversMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487
Figure 14. Receiver Propagation Delay Test Circuit
Figure 15. MAX481/MAX485/MAX490/MAX491/MAX1487Receiver tPHL
Figure 16. MAX481/MAX485/MAX490/MAX491/MAX1487Receiver tPLH
PHLFigure 18. MAX483, MAX487–MAX489 Receiver tPLH
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12______________________________________________________________________________
________
Low-Power, Slew-Rate-LimitedRS-485/RS-422 Transceivers
Line Length vs. Data Rate
Figures 21 and 22 show typical network applicationsThe RS-485/RS-422 standard covers
line lengthhttp://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92s up tocircuits.
These parts can also be used as line4000 feet. For line lengths greater than 4000
feet, seerepeaters, with cable lengths longer than 4000 feet, asFigure 23.
shown in Figure 23.
Figures 19 and 20 show the system differential voltageTo minimize reflections, the
line should be terminated atfor the parts driving 4000 feet of 26AWG twisted-pairboth
ends in its characteristic impedance, and stubwire at 110kHz into 120?loads.
lengths off the main line should be kept as short as possi-Typical Applications
ble. The slew-rate-limited MAX483 and MAX487–MAX489The MAX481, MAX483, MAX485,
MAX487–MAX491, andare more tolerant of imperfect termination.
MAX1487 transceivers are designed for bidirectional datacommunications on multipoint
bus transmission lines.
DI
5V0V
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1V
VY-VZ
0V-1V
RO
5V0V
2?s/div
Figure
19.http://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92
MAX481/MAX485/MAX490/MAX491/MAX1487 SystemFigure 20. MAX483, MAX487–MAX489 System
DifferentialDifferential Voltage at 110kHz Driving 4000ft of CableVoltage at 110kHz
Driving 4000ft of Cable
Figure 21. MAX481/MAX483/MAX485/MAX487/MAX1487 Typical Half-Duplex RS-485 Network
________________________________________________________________________________
______13
MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487
Low-Power,
Slew-Rate-LimitedRS-485/RS-422
TransceiversMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487
Figure 22. MAX488–MAX491 Full-Duplex RS-485 Network
Isolated RS-485
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For isolated RS-485 applications, see the MAX253 andMAX1480 data sheets.
Figure 23. Line Repeater for MAX488–MAX491
14______________________________________________________________________________
________
Low-Power, Slew-Rate-LimitedRS-485/RS-422 Transceivers
_______________Ohttp://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92rdering
Information
__Ordering Information (continued)
*
Contact factory for dice specifications.
_________________Chip Topographies
MAX481/MAX483/MAX485/MAX487/MAX1487
________________________________________________________________________________
______15
MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487
Low-Power,
Slew-Rate-LimitedRS-485/RS-422
TransceiversMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487
_____________________________________________Chip Topographies (continued)
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MAX488/MAX490
MAX489/MAX491
SUBSTRATE CONNECTED TO GND
16______________________________________________________________________________
________
Low-Power, Slew-Rate-LimitedRS-485/RS-422 Transceivers
Package Information
(The package drawing(s) in this data sheet may not reflect the most current
specifications.
For
the
latest
package
ouhttp://www.wendangwang.com/doc/eeec96abb6ebb3bc58160b92tline
informationgo
to .)
S
PE.
NCIOS___________________________________________________________________________
___________17
MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487
Low-Power,
Slew-Rate-LimitedRS-485/RS-422
TransceiversMAX481/MAX483/MAX485/MAX487–MAX491/MAX1487
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Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current
specifications. For the latest package outline informationgo to .)
18______________________________________________________________________________
________
Low-Power, Slew-Rate-LimitedRS-485/RS-422 Transceivers
7
Package Information (continued)
8(The package drawing(s) in this data sheet may not reflect the most current
specifications. For the latest package outline information4go to .)
1XS
P
E.ANPIDPM/194XAM–784XAM/584XAM/384XAM/184XAMMaximhttp://www.wendangwang.com/doc
/eeec96abb6ebb3bc58160b92 cannot assume responsibility for use of any circuitry
other than circuitry entirely embodied in a Maxim product. No circuit patent licenses
areimplied. Maxim reserves the right to change the circuitry and specifications
without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA
____________________19?2003 Maxim Integrated Products
94086 408-737-7600
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Printed USA
is a registered trademark of Maxim Integrated Products.
MAX481/MAX483/MAX485/MAX487–MAX491
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