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19-0410; Rev 3; 7/96
15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceivers
_______________General Description
The MAX481E, MAX483E, MAX485E, MAX487E-MAX491E, and MAX1487E are low-power transceivers for RS-485 and RS-422 communications in harsh environments. Each driver output and receiver input is protected against 15kV electrostatic discharge (ESD) shocks, without latchup. These parts contain one driver and one receiver. The MAX483E, MAX487E, MAX488E, and MAX489E feature reduced slewrate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, thus allowing error-free data transmission up to 250kbps. The driver slew rates of the MAX481E, MAX485E, MAX490E, MAX491E, and MAX1487E are not limited, allowing them to transmit up to 2.5Mbps. These transceivers draw as little as 120A supply current when unloaded or when fully loaded with disabled drivers (see Selection Table). Additionally, the MAX481E, MAX483E, and MAX487E have a low-current shutdown mode in which they consume only 0.5A. All parts operate from a single +5V supply. Drivers are short-circuit current limited, and are protected against excessive power dissipation by thermal shutdown circuitry that places their 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 MAX487E and MAX1487E feature quarter-unit-load receiver input impedance, allowing up to 128 transceivers on the bus. The MAX488E-MAX491E are designed for fullduplex communications, while the MAX481E, MAX483E, MAX485E, MAX487E, and MAX1487E are designed for halfduplex applications. For applications that are not ESD sensitive see the pin- and function-compatible MAX481, MAX483, MAX485, MAX487-MAX491, and MAX1487.
____________________________Features
o ESD Protection: 15kV--Human Body Model o Slew-Rate Limited for Error-Free Data Transmission (MAX483E/487E/488E/489E) o Low Quiescent Current: 120A (MAX483E/487E/488E/489E) 230A (MAX1487E) 300A (MAX481E/485E/490E/491E) o -7V to +12V Common-Mode Input Voltage Range o Three-State Outputs o 30ns Propagation Delays, 5ns Skew (MAX481E/485E/490E/491E/1487E) o Full-Duplex and Half-Duplex Versions Available o Allows up to 128 Transceivers on the Bus (MAX487E/MAX1487E) o Current Limiting and Thermal Shutdown for Driver Overload Protection
MAX481E/MAX483E/MAX485E/MAX487E-MAX491E/MAX1487E
______________Ordering Information
PART MAX481ECPA MAX481ECSA MAX481EEPA MAX481EESA TEMP. RANGE 0C to +70C 0C to +70C -40C to +85C -40C to +85C PIN-PACKAGE 8 Plastic DIP 8 SO 8 Plastic DIP 8 SO
________________________Applications
Low-Power RS-485 Transceivers Low-Power RS-422 Transceivers Level Translators Transceivers for EMI-Sensitive Applications Industrial-Control Local Area Networks
Ordering Information continued on last page.
______________________________________________________________Selection Table
PART NUMBER MAX481E MAX483E MAX485E MAX487E MAX488E MAX489E MAX490E MAX491E MAX1487E HALF/FULL DUPLEX Half Half Half Half Full Full Full Full Half DATA RATE (Mbps) 2.5 0.25 2.5 0.25 0.25 0.25 2.5 2.5 2.5 SLEW-RATE LIMITED No Yes No Yes Yes Yes No No No LOW-POWER SHUTDOWN Yes Yes No Yes No No No No No RECEIVER/ DRIVER ENABLE Yes Yes Yes Yes No Yes No Yes Yes QUIESCENT CURRENT (A) 300 120 300 120 120 120 300 300 230 NUMBER OF TRANSMITTERS ON BUS 32 32 32 128 32 32 32 32 128 PIN COUNT 8 8 8 8 8 14 8 14 8
________________________________________________________________ Maxim Integrated Products
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15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceivers
MAX481E/MAX483E/MAX485E/MAX487E-MAX491E/MAX1487E
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (VCC) .............................................................12V -- -- Control Input Voltage (RE , DE)...................-0.5V to (VCC + 0.5V) Driver Input Voltage (DI).............................-0.5V to (VCC + 0.5V) Driver Output Voltage (Y, Z; A, B) ..........................-8V to +12.5V Receiver Input Voltage (A, B).................................-8V to +12.5V Receiver Output Voltage (RO)....................-0.5V to (VCC + 0.5V) Continuous Power Dissipation (TA = +70C) 8-Pin Plastic DIP (derate 9.09mW/C above +70C) ....727mW 14-Pin Plastic DIP (derate 10.00mW/C above +70C) ..800mW 8-Pin SO (derate 5.88mW/C above +70C).................471mW 14-Pin SO (derate 8.33mW/C above +70C)...............667mW Operating Temperature Ranges MAX4_ _C_ _/MAX1487EC_ A .............................0C to +70C MAX4_ _E_ _/MAX1487EE_ A...........................-40C to +85C Storage Temperature Range .............................-65C to +160C Lead Temperature (soldering, 10sec) .............................+300C
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.
DC ELECTRICAL CHARACTERISTICS
(VCC = 5V 5%, TA = TMIN to TMAX, unless otherwise noted.) (Notes 1, 2) PARAMETER Differential Driver Output (no load) Differential Driver Output (with load) Change in Magnitude of Driver Differential Output Voltage for Complementary Output States Driver Common-Mode Output Voltage Change in Magnitude of Driver Common-Mode Output Voltage for Complementary Output States Input High Voltage Input Low Voltage Input Current SYMBOL VOD1 VOD2 VOD VOC VOD VIH VIL IIN1 R = 50 (RS-422) R = 27 (RS-485), Figure 8 R = 27 or 50, Figure 8 R = 27 or 50, Figure 8 R = 27 or 50, Figure 8 -- -- DE, DI, RE -- -- DE, DI, RE -- -- DE, DI, RE DE = 0V; VCC = 0V or 5.25V, all devices except MAX487E/MAX1487E MAX487E/MAX1487E, DE = 0V, VCC = 0V or 5.25V Receiver Differential Threshold Voltage Receiver Input Hysteresis Receiver Output High Voltage Receiver Output Low Voltage Three-State (high impedance) Output Current at Receiver VTH VTH VOH VOL IOZR -7V VCM 12V VCM = 0V IO = -4mA, VID = 200mV IO = 4mA, VID = -200mV 0.4V VO 2.4V -7V VCM 12V, all devices except MAX487E/MAX1487E Receiver Input Resistance RIN -7V VCM 12V, MAX487E/MAX1487E 48 k 12 3.5 0.4 1 VIN = 12V VIN = -7V VIN = 12V VIN = -7V -0.2 70 2.0 0.8 2 1.0 mA -0.8 0.25 -0.2 0.2 mA V mV V V A k 2 1.5 5 0.2 3 0.2 CONDITIONS MIN TYP MAX 5 UNITS V V
V V V V V A
Input Current (A, B)
IIN2
2
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15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceivers
DC ELECTRICAL CHARACTERISTICS (continued)
(VCC = 5V 5%, TA = TMIN to TMAX, unless otherwise noted.) (Notes 1, 2) PARAMETER SYMBOL CONDITIONS MAX488E/MAX489E, -- -- DE, DI, RE = 0V or VCC MAX490E/MAX491E, -- -- DE, DI, RE = 0V or VCC No-Load Supply Current (Note 3) ICC MAX481E/MAX485E, -- -- RE = 0V or VCC MAX1487E, -- -- RE = 0V or VCC MAX483E/MAX487E, -- -- RE = 0V or VCC Supply Current in Shutdown Driver Short-Circuit Current, VO = High Driver Short-Circuit Current, VO = Low Receiver Short-Circuit Current ESD Protection ISHDN IOSD1 IOSD2 IOSR DE = VCC DE = 0V DE = VCC DE = 0V DE = VCC MAX483E MAX487E MIN TYP 120 300 500 300 300 230 350 250 120 0.5 35 35 7 15 MAX 250 500 900 500 500 400 650 400 250 10 250 250 95 A UNITS
MAX481E/MAX483E/MAX485E/MAX487E-MAX491E/MAX1487E
DE = 0V -- -- MAX481E/483E/487E, DE = 0V, RE = VCC -7V VO 12V (Note 4) -7V VO 12V (Note 4) 0V VO VCC A, B, Y and Z pins, tested using Human Body Model
A mA mA mA kV
SWITCHING CHARACTERISTICS--MAX481E/MAX485E, MAX490E/MAX491E, MAX1487E
(VCC = 5V 5%, TA = TMIN to TMAX, unless otherwise noted.) (Notes 1, 2) PARAMETER SYMBOL CONDITIONS Driver Input to Output Driver Output Skew to Output 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 tPLH tPHL tSKEW tR, tF tZH tZL tLZ tHZ Figures 10 and 12, RDIFF = 54, CL1 = CL2 = 100pF Figures 10 and 12, RDIFF = 54, CL1 = CL2 = 100pF Figures 10 and 12, MAX481E, MAX485E, MAX1487E RDIFF = 54, CL1 = CL2 = 100pF MAX490EC/E, MAX491EC/E Figures 11 and 13, CL = 100pF, S2 closed Figures 11 and 13, CL = 100pF, S1 closed Figures 11 and 13, CL = 15pF, S1 closed Figures 11 and 13, CL = 15pF, S2 closed 20 20 3 5 MIN 10 10 TYP 40 40 5 20 20 45 45 45 45 60 60 5 20 20 20 20 2.5 50 200 50 50 50 50 600 MAX 60 60 10 40 ns 25 70 70 70 70 200 ns 150 ns ns ns ns ns Mbps ns ns ns ns ns UNITS ns ns
Figures 10 and 14, MAX481E, MAX485E, MAX1487E tPLH, tPHL RDIFF = 54, CL1 = CL2 = 100pF MAX490EC/E, MAX491EC/E tSKD tZL tZH tLZ tHZ fMAX tSHDN Figures 10 and 14, RDIFF = 54, CL1 = CL2 = 100pF Figures 9 and 15, CRL = 15pF, S1 closed Figures 9 and 15, CRL = 15pF, S2 closed Figures 9 and 15, CRL = 15pF, S1 closed Figures 9 and 15, CRL = 15pF, S2 closed MAX481E (Note 5)
| tPLH - tPHL | Differential Receiver Skew Receiver Enable to Output Low Receiver Enable to Output High Receiver Disable Time from Low Receiver Disable Time from High Maximum Data Rate Time to Shutdown
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15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceivers
MAX481E/MAX483E/MAX485E/MAX487E-MAX491E/MAX1487E
SWITCHING CHARACTERISTICS--MAX481E/MAX485E, MAX490E/MAX491E, MAX1487E (continued)
(VCC = 5V 5%, TA = TMIN to TMAX, unless otherwise noted.) (Notes 1, 2) PARAMETER SYMBOL CONDITIONS Figures 11 and 13, CL = 100pF, S2 closed Figures 11 and 13, CL = 100pF, S1 closed Figures 9 and 15, CL = 15pF, S2 closed, A - B = 2V Figures 9 and 15, CL = 15pF, S1 closed, B - A = 2V MIN TYP 45 45 225 225 MAX 100 100 1000 1000 UNITS ns ns ns ns
Driver Enable from Shutdown to tZH(SHDN) Output High (MAX481E) Driver Enable from Shutdown to tZL(SHDN) Output Low (MAX481E) Receiver Enable from Shutdown tZH(SHDN) to Output High (MAX481E) Receiver Enable from Shutdown tZL(SHDN) to Output Low (MAX481E)
SWITCHING CHARACTERISTICS--MAX483E, MAX487E/MAX488E/MAX489E
(VCC = 5V 5%, TA = TMIN to TMAX, unless otherwise noted.) (Notes 1, 2) PARAMETER Driver Input to Output Driver Output Skew to Output 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 SYMBOL tPLH tPHL tSKEW tR, tF tZH tZL tLZ tHZ tPLH tPHL tSKD tZL tZH tLZ tHZ fMAX tSHDN tZH(SHDN) tZL(SHDN) tZH(SHDN) tZL(SHDN) CONDITIONS Figures 10 and 12, RDIFF = 54, CL1 = CL2 = 100pF Figures 10 and 12, RDIFF = 54, CL1 = CL2 = 100pF Figures 10 and 12, RDIFF = 54, CL1 = CL2 = 100pF Figures 11 and 13, CL = 100pF, S2 closed Figures 11 and 13, CL = 100pF, S1 closed Figures 11 and 13, CL = 15pF, S1 closed Figures 11 and 13, CL = 15pF, S2 closed Figures 10 and 14, RDIFF = 54, CL1 = CL2 = 100pF Figures 10 and 14, RDIFF = 54, CL1 = CL2 = 100pF Figures 9 and 15, CRL = 15pF, S1 closed Figures 9 and 15, CRL = 15pF, S2 closed Figures 9 and 15, CRL = 15pF, S1 closed Figures 9 and 15, CRL = 15pF, S2 closed tPLH, tPHL < 50% of data period MAX483E/MAX487E (Note 5) MAX483E/MAX487E, Figures 11 and 13, CL = 100pF, S2 closed MAX483E/MAX487E, Figures 11 and 13, CL = 100pF, S1 closed MAX483E/MAX487E, Figures 9 and 15, CL = 15pF, S2 closed MAX483E/MAX487E, Figures 9 and 15, CL = 15pF, S1 closed 250 50 200 600 2000 2000 2500 2500 250 250 250 300 300 250 250 100 25 25 25 25 50 50 50 50 MIN 250 250 TYP 800 800 20 MAX 2000 2000 800 2000 2000 2000 3000 3000 2000 2000 UNITS ns ns ns ns ns ns ns ns ns ns ns ns ns kbps ns ns ns ns ns
I tPLH - tPHL I Differential
Receiver Skew Receiver Enable to Output Low Receiver Enable to Output High Receiver Disable Time from Low Receiver Disable Time from High Maximum Data Rate Time to Shutdown Driver Enable from Shutdown to Output High Driver Enable from Shutdown to Output Low Receiver Enable from Shutdown to Output High Receiver Enable from Shutdown to Output Low
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15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-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 = +25C. Note 3: Supply current specification is valid for loaded transmitters when DE = 0V. Note 4: Applies to peak current. See Typical Operating Characteristics. -- -- Note 5: The MAX481E/MAX483E/MAX487E are put into shutdown by bringing RE high and DE low. 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 are guaranteed to have entered shutdown. See Low-Power Shutdown Mode section.
MAX481E/MAX483E/MAX485E/MAX487E-MAX491E/MAX1487E
__________________________________________Typical Operating Characteristics
(VCC = 5V, TA = +25C, unless otherwise noted.)
OUTPUT CURRENT vs. RECEIVER OUTPUT LOW VOLTAGE
MAX481E-01
OUTPUT CURRENT vs. RECEIVER OUTPUT HIGH VOLTAGE
MAX481E-02
RECEIVER OUTPUT HIGH VOLTAGE vs. TEMPERATURE
4.6 OUTPUT HIGH VOLTAGE (V) 4.4 4.2 4.0 3.8 3.6 3.4 3.2
MAX481E-03
50 45 OUTPUT CURRENT (mA) 40 35 30 25 20 15 10 5 0 0 0.5 1.0 1.5 2.0
-25
4.8 IRO = 8mA
OUTPUT CURRENT (mA)
-20
-15
-10
-5 0 2.5 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 OUTPUT LOW VOLTAGE (V) OUTPUT HIGH VOLTAGE (V)
3.0 -60 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
RECEIVER OUTPUT LOW VOLTAGE vs. TEMPERATURE
MAX481E-04
DRIVER OUTPUT CURRENT vs. DIFFERENTIAL OUTPUT VOLTAGE
80 OUTPUT CURRENT (mA) 70 60 50 40 30 20 10 0
MAX481E-05
0.9 0.8 OUTPUT LOW VOLTAGE (V) 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 -60 -40 -20 0 20 40 60 IRO = 8mA
90
80 100
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 DIFFERENTIAL OUTPUT VOLTAGE (V)
TEMPERATURE (C)
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15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceivers
MAX481E/MAX483E/MAX485E/MAX487E-MAX491E/MAX1487E
____________________________Typical Operating Characteristics (continued)
(VCC = 5V, TA = +25C, unless otherwise noted.)
DRIVER DIFFERENTIAL OUTPUT VOLTAGE vs. TEMPERATURE
DIFFERENTIAL OUTPUT VOLTAGE (V) R = 54 2.2 2.1 2.0 1.9 1.8 1.7 1.6 1.5 -60 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
MAX481E-06
OUTPUT CURRENT vs. DRIVER OUTPUT LOW VOLTAGE
MAX481E-07
OUTPUT CURRENT vs. DRIVER OUTPUT HIGH VOLTAGE
-90 OUTPUT CURRENT (mA) -80 -70 -60 -50 -40 -30 -20
MAX481E-08
2.3
140 120 OUTPUT CURRENT (mA) 100 80 60 40 20 0 0 2 4 6 8 10
-100
-10 0 12 -8 -6 -4 -2 0 2 4 6 OUTPUT LOW VOLTAGE (V) OUTPUT HIGH VOLTAGE (V)
MAX481E/MAX485E/MAX490E/MAX491E SUPPLY CURRENT vs. TEMPERATURE
MAX481E-09
MAX483E/MAX487E-MAX489E SUPPLY CURRENT vs. TEMPERATURE
MAX481E-10
MAX1487E SUPPLY CURRENT vs. TEMPERATURE
MAX481E-11
600
MAX481E/MAX485E; DE = VCC, RE = X
600 500 SUPPLY CURRENT (A)
600 500 SUPPLY CURRENT (A) 400
MAX1487E; DE = VCC, RE = X
500 SUPPLY CURRENT (A) 400 300 200 100
MAX481E; DE = 0, RE = VCC MAX485E; DE = 0, RE = X, MAX481E; DE = RE = 0 MAX490E/MAX491E; DE = RE = X
400 300 200 100
MAX483E; DE = VCC, RE = X
300 200 100
MAX487E; DE = VCC, RE = X MAX483E/MAX487E; DE = RE = 0, MAX488E/MAX489E; DE = RE = X
MAX1487E; DE = 0V, RE = X
MAX483E/MAX487E; DE = 0, RE = VCC
0 -60 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
0 -60 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
0 -60 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
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15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceivers
______________________________________________________________Pin Description
PIN MAX481E/MAX483E MAX485E/MAX487E MAX1487E NAME FUNCTION
MAX481E/MAX483E/MAX485E/MAX487E-MAX491E/MAX1487E MAX481E/MAX483E/MAX485E/MAX487E-MAX491E/MAX1487E
MAX488E MAX490E
MAX489E MAX491E
1 2
2 --
2 3
RO -- -- RE
Receiver Output: If A > B by 200mV, RO will be high; If A < B by 200mV, RO will be low. -- -- Receiver Output Enable. RO is enabled when RE is -- -- low; RO is high impedance when RE is high. Driver Output Enable. The driver outputs, Y and Z, are enabled by bringing DE high. They are high impedance when DE is low. If the driver outputs are enabled, the parts function as line drivers. While they are high -- -- impedance, they function as line receivers if R E is low. Driver Input. A low on DI forces output Y low and output Z high. Similarly, a high on DI forces output Y high and output Z low. Ground Noninverting Driver Output Inverting Driver Output Noninverting Receiver Input and Noninverting Driver Output Noninverting Receiver Input Inverting Receiver Input and Inverting Driver Output Inverting Receiver Input Positive Supply: 4.75V VCC 5.25V No Connect--not internally connected
3
--
4
DE
4 5 -- -- 6 -- 7 -- 8 --
3 4 5 6 -- 8 -- 7 1 --
5 6, 7 9 10 -- 12 -- 11 14 1, 8, 13
DI GND Y Z A A B B VCC N.C.
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15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceivers
MAX481E/MAX483E/MAX485E/MAX487E-MAX491E/MAX1487E
MAX481E MAX483E MAX485E MAX487E MAX1487E
B Rt A R RE NOTE: PIN LABELS Y AND Z ON TIMING, TEST, AND WAVEFORM DIAGRAMS REFER TO PINS A AND B WHEN DE IS HIGH. TYPICAL OPERATING CIRCUIT SHOWN WITH DIP/SO PACKAGE. RO
TOP VIEW
RO 1 R 8 7 6 D 5 VCC B A GND RO 1 R 8 VCC 7B Rt 6 A 5 GND
0.1F
DE D DI
RE 2 DE 3 DI 4
RE 2 DE 3 DI 4 D
DIP/SO
Figure 1. MAX481E/MAX483E/MAX485E/MAX487E/MAX1487E Pin Configuration and Typical Operating Circuit
0.1F VCC 1 VCC
MAX488E MAX490E
5Y Rt 6Z
TOP VIEW
VCC 1 RO 2 DI 3 GND 4 D R 8 7 6 5 A B Z Y RO DI
3
D
R
RO
8A 2
R
Rt 7 B
D
DI
DIP/SO
4 GND GND NOTE: TYPICAL OPERATING CIRCUIT SHOWN WITH DIP/SO PACKAGE.
Figure 2. MAX488E/MAX490E Pin Configuration and Typical Operating Circuit
TOP VIEW
N.C. 1 RO RE DE DI GND GND 2 3 4 5 6 7 D R 14 V CC 13 N.C. 12 A 11 B 10 Z 9 8 Y N.C. NC 1, 8, 13 3 6, 7 GND RE GND DE RO 2 DI 5 DE 4 VCC 14 9 0.1F VCC RE
Y
MAX489E MAX491E
Rt
D
10 Z 12 A Rt 11 B
R
RO
R
D
DI
DIP/SO
Figure 3. MAX489E/MAX491E Pin Configuration and Typical Operating Circuit
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15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceivers
__________Function Tables (MAX481E/MAX483E/MAX485E/MAX487E/MAX1487E)
Table 1. Transmitting
INPUTS RE X X 0 1 DE 1 1 0 0 DI 1 0 X X Z 0 1 High-Z High-Z* OUTPUTS Y 1 0 High-Z High-Z* RE 0 0 0 1
MAX481E/MAX483E/MAX485E/MAX487E-MAX491E/MAX1487E
Table 2. Receiving
INPUTS DE 0 0 0 0 A-B > +0.2V < -0.2V Inputs open X OUTPUT RO 1 0 1 High-Z*
X = Don't care High-Z = High impedance * Shutdown mode for MAX481E/MAX483E/MAX487E
X = Don't care High-Z = High impedance * Shutdown mode for MAX481E/MAX483E/MAX487E
__________Applications Information
The MAX481E/MAX483E/MAX485E/MAX487E-MAX491E and MAX1487E are low-power transceivers for RS-485 and RS-422 communications. These "E" versions of the MAX481, MAX483, MAX485, MAX487-MAX491, and MAX1487 provide extra protection against ESD. The rugged MAX481E, MAX483E, MAX485E, MAX497E- MAX491E, and MAX1487E are intended for harsh environments where high-speed communication is important. These devices eliminate the need for transient suppressor diodes and the associated high capacitance loading. The standard (non-"E") MAX481, MAX483, MAX485, MAX487-MAX491, and MAX1487 are recommended for applications where cost is critical. The MAX481E, MAX485E, MAX490E, MAX491E, and MAX1487E can transmit and receive at data rates up to 2.5Mbps, while the MAX483E, MAX487E, MAX488E, and MAX489E are specified for data rates up to 250kbps. The MAX488E-MAX491E are full-duplex transceivers, while the MAX481E, MAX483E, MAX487E, and MAX1487E are half-duplex. In addition, driverenable (DE) and receiver-enable (RE) pins are included on the MAX481E, MAX483E, MAX485E, MAX487E, MAX489E, MAX491E, and MAX1487E. When disabled, the driver and receiver outputs are high impedance.
neers developed state-of-the-art structures to protect these pins against ESD of 15kV without damage. The ESD structures withstand high ESD in all states: normal operation, shutdown, and powered down. After an ESD event, Maxim's MAX481E, MAX483E, MAX485E, MAX487E-MAX491E, and MAX1487E keep working without latchup. ESD protection can be tested in various ways; the transmitter outputs and receiver inputs of this product family are characterized for protection to 15kV using the Human Body Model. Other ESD test methodologies include IEC10004-2 contact discharge and IEC1000-4-2 air-gap discharge (formerly IEC801-2).
ESD Test Conditions ESD performance depends on a variety of conditions. Contact Maxim for a reliability report that documents test set-up, test methodology, and test results. Human Body Model Figure 4 shows the Human Body Model, and Figure 5 shows the current waveform it generates when discharged into a low impedance. This model consists of a 100pF capacitor charged to the ESD voltage of interest, which is then discharged into the test device through a 1.5k resistor. IEC1000-4-2 The IEC1000-4-2 standard covers ESD testing and performance of finished equipment; it does not specifically refer to integrated circuits (Figure 6).
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15kV ESD Protection
As with all Maxim devices, ESD-protection structures are incorporated on all pins to protect against electrostatic discharges encountered during handling and assembly. The driver outputs and receiver inputs have extra protection against static electricity. Maxim's engi-
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15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceivers
MAX481E/MAX483E/MAX485E/MAX487E-MAX491E/MAX1487E
R C 1M CHARGE CURRENT LIMIT RESISTOR HIGH VOLTAGE DC SOURCE R D 1500 DISCHARGE RESISTANCE DEVICE UNDER TEST IP 100% 90% AMPERES 36.8% 10% 0 0 tRL TIME tDL CURRENT WAVEFORM Ir PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE)
Cs 100pF
STORAGE CAPACITOR
Figure 4. Human Body ESD Test Model
Figure 5. Human Body Model Current Waveform
I 100% R C 50M to 100M CHARGE CURRENT LIMIT RESISTOR HIGHVOLTAGE DC SOURCE R D 330 I PEAK DISCHARGE RESISTANCE DEVICE UNDER TEST 10% t r = 0.7ns to 1ns t 30ns 60ns 90%
Cs 150pF
STORAGE CAPACITOR
Figure 6. IEC1000-4-2 ESD Test Model
Figure 7. IEC1000-4-2 ESD Generator Current Waveform
Y R VOD R Z VOC S2 TEST POINT RECEIVER OUTPUT CRL 15pF 1k VCC S1 1k
Figure 8. Driver DC Test Load
Figure 9. Receiver Timing Test Load
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15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceivers
MAX481E/MAX483E/MAX485E/MAX487E-MAX491E/MAX1487E
3V DE DI Y VID Z CL2
CL1 RDIFF
A RO B RE 500 OUTPUT UNDER TEST CL S2 S1
VCC
Figure 10. Driver/Receiver Timing Test Circuit
Figure 11. Driver Timing Test Load
3V DI 0V 1.5V tPLH tPHL 1.5V 1/2 VO
3V DE 0V tZL(SHDN), tZL Y, Z VO VOL VDIFF = V (Y) - V (Z) 90% 90% tF tSKEW = | tPLH - tPHL | 10% Y, Z 2.3V 0V tZH(SHDN), tZH tHZ 2.3V OUTPUT NORMALLY LOW OUTPUT NORMALLY HIGH VOH -0.5V VOL +0.5V tLZ 1.5V 1.5V
Z Y 1/2 VO VO VDIFF 0V -VO 10% tR
Figure 12. Driver Propagation Delays
Figure 13. Driver Enable and Disable Times (except MAX488E and MAX490E)
3V RE 0V RO VOH VOL VID -VID 0V 1.5V tPHL INPUT OUTPUT tPLH 0V RO 0V tZH(SHDN), tZH tHZ 1.5V 1.5V VCC RO tZL(SHDN), tZL tLZ VOL + 0.5V 1.5V 1.5V
1.5V OUTPUT NORMALLY LOW OUTPUT NORMALLY HIGH
A-B
VOH - 0.5V
Figure 14. Receiver Propagation Delays
Figure 15. Receiver Enable and Disable Times (except MAX488E and MAX490E)
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11
15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceivers
MAX481E/MAX483E/MAX485E/MAX487E-MAX491E/MAX1487E
10dB/div
10dB/div
0Hz
500kHz/div
5MHz
0Hz
500kHz/div
5MHz
Figure 16. Driver Output Waveform and FFT Plot of MAX485E/MAX490E/MAX491E/MAX1487E Transmitting a 150kHz Signal
Figure 17. Driver Output Waveform and FFT Plot of MAX483E/MAX487E-MAX489E Transmitting a 150kHz Signal
The major difference between tests done using the Human Body Model and IEC1000-4-2 is higher peak current in IEC1000-4-2, because series resistance is lower in the IEC1000-4-2 model. Hence, the ESD withstand voltage measured to IEC1000-4-2 is generally lower than that measured using the Human Body Model. Figure 7 shows the current waveform for the 8kV IEC1000-4-2 ESD contact-discharge test. The air-gap test involves approaching the device with a charged probe. The contact-discharge method connects the probe to the device before the probe is energized.
MAX483E/MAX487E/MAX488E/MAX489E: Reduced EMI and Reflections
The MAX483E and MAX487E-MAX489E are slew-rate limited, minimizing EMI and reducing reflections caused by improperly terminated cables. Figure 16 shows the driver output waveform and its Fourier analysis of a 150kHz signal transmitted by a MAX481E, MAX485E, MAX490E, MAX491E, or MAX1487E. Highfrequency harmonics with large amplitudes are evident. Figure 17 shows the same information displayed for a MAX483E, MAX487E, MAX488E, or MAX489E transmitting under the same conditions. Figure 17's high-frequency harmonics have much lower amplitudes, and the potential for EMI is significantly reduced.
Machine Model The Machine Model for ESD tests all pins using a 200pF storage capacitor and zero discharge resistance. Its objective is to emulate the stress caused by contact that occurs with handling and assembly during manufacturing. Of course, all pins require this protection during manufacturing--not just inputs and outputs. Therefore, after PC board assembly, the Machine Model is less relevant to I/O ports.
Low-Power Shutdown Mode (MAX481E/MAX483E/MAX487E)
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. In shutdown, the devices typically draw only 0.5A of supply current. RE and DE may be driven simultaneously; the parts are guaranteed not to enter shutdown if RE is high and DE is low for less than 50ns. If the inputs are in this state for at least 600ns, the parts are guaranteed to enter shutdown. For the MAX481E, MAX483E, and MAX487E, the t ZH and tZL enable times assume the part was not in the low-power shutdown state (the MAX485E, MAX488E- MAX491E, and MAX1487E can not be shut down). The t ZH(SHDN) and t ZL(SHDN) enable times assume the parts were shut down (see Electrical Characteristics).
MAX487E/MAX1487E: 128 Transceivers on the Bus
The 48k, 1/4-unit-load receiver input impedance of the MAX487E and MAX1487E allows up to 128 transceivers on a bus, compared to the 1-unit load (12k input impedance) of standard RS-485 drivers (32 transceivers maximum). Any combination of MAX487E/MAX1487E and other RS-485 transceivers with a total of 32 unit loads or less can be put on the bus. The MAX481E, MAX483E, MAX485E, and MAX488E-MAX491E have standard 12k receiver input impedance.
12
______________________________________________________________________________________
15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceivers
delay times. Typical propagation delays are shown in Figures 19-22 using Figure 18's test circuit. The difference in receiver delay times, tPLH - tPHL, is typically under 13ns for the MAX481E, MAX485E, MAX490E, MAX491E, and MAX1487E, and is typically less than 100ns for the MAX483E and MAX487E- MAX489E. The driver skew times are typically 5ns (10ns max) for the MAX481E, MAX485E, MAX490E, MAX491E, and MAX1487E, and are typically 100ns (800ns max) for the MAX483E and MAX487E-MAX489E.
MAX481E/MAX483E/MAX485E/MAX487E-MAX491E/MAX1487E
100pF Z TTL IN tR, tF < 6ns D Y R = 54 A B R RECEIVER OUT
100pF
Typical Applications
The MAX481E, MAX483E, MAX485E, MAX487E- MAX491E, and MAX1487E transceivers are designed for bidirectional data communications on multipoint bus transmission lines. Figures 25 and 26 show typical network application circuits. These parts can also be used as line repeaters, with cable lengths longer than 4000 feet. To minimize reflections, the line should be terminated at both ends in its characteristic impedance, and stub lengths off the main line should be kept as short as possible. The slew-rate-limited MAX483E and MAX487E- MAX489E are more tolerant of imperfect termination. Bypass the VCC pin with 0.1F.
Figure 18. Receiver Propagation Delay Test Circuit
It takes the drivers and receivers longer to become enabled from the low-power shutdown state (tZH(SHDN), tZL(SHDN)) than from the operating mode (tZH, tZL). (The parts are in operating mode if the RE, DE inputs equal a logical 0,1 or 1,1 or 0, 0.)
Driver Output Protection
Excessive output current and power dissipation caused by faults or by bus contention are prevented by two mechanisms. A foldback current limit on the output stage provides immediate protection against short circuits over the whole common-mode voltage range (see Typical Operating Characteristics). In addition, a thermal shutdown circuit forces the driver outputs into a high-impedance state if the die temperature rises excessively.
Isolated RS-485
For isolated RS-485 applications, see the MAX253 and MAX1480 data sheets.
Line Length vs. Data Rate
The RS-485/RS-422 standard covers line lengths up to 4000 feet. Figures 23 and 24 show the system differential voltage for the parts driving 4000 feet of 26AWG twisted-pair wire at 110kHz into 100 loads.
Propagation Delay
Many digital encoding schemes depend on the difference between the driver and receiver propagation
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13
15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceivers
MAX481E/MAX483E/MAX485E/MAX487E-MAX491E/MAX1487E
A B
500mV/div
500mV/div
B RO 5V/div
A
5V/div RO
25ns/div
25ns/div
Figure 19. MAX481E/MAX485E/MAX490E/MAX1487E Receiver tPHL
Figure 20. MAX481E/MAX485E/MAX490E/MAX491E/ MAX1487E Receiver tPLH
A
B
500mV/div
500mV/div
B RO 5V/div
A
5V/div RO
200ns/div
200ns/div
Figure 21. MAX483E/MAX487E-MAX489E Receiver tPHL
Figure 22. MAX483E/MAX487E-MAX489E Receiver tPLH
DI
5V 0V
DI
5V 0V 1V
VA - VB
0 -1V 5V
VB - VA
0 -1V
DO
5V 0V
DO
0V
2s/div
2s/div
Figure 23. MAX481E/MAX485E/MAX490E/MAX491E/ MAX1487E System Differential Voltage at 110kHz Driving 4000ft of Cable
14
Figure 24. MAX483E/MAX1487E-MAX489E System Differential Voltage at 110kHz Driving 4000ft of Cable
______________________________________________________________________________________
15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceivers
MAX481E/MAX483E/MAX485E/MAX487E-MAX491E/MAX1487E
120 DI B 120 B DE
D
DE RO RE A B A B A A
D
DI
R R R D
R
RO RE
MAX481E MAX483E MAX485E MAX487E MAX1487E
D
DI
DE
RO RE
DI
DE
RO RE
Figure 25. MAX481E/MAX483E/MAX485E/MAX487E/MAX1487E Typical Half-Duplex RS-485 Network
A RO RE DE Z DI
Y 120 120 Z DE B 120 120 Y Z B A Y Z B A A RE RO
R
B
D
DI
D
Y
R
R D D
R
DI
DE RE RO
DI
DE RE RO
MAX488E MAX489E MAX490E MAX491E
NOTE: RE AND DE ON MAX489E/MAX491E ONLY.
Figure 26. MAX488E-MAX491E Full-Duplex RS-485 Network
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15
15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceivers
MAX481E/MAX483E/MAX485E/MAX487E-MAX491E/MAX1487E
___________________________________________Ordering Information (continued)
PART MAX483ECPA MAX483ECSA MAX483EEPA MAX483EESA MAX485ECPA MAX485ECSA MAX485EEPA MAX485EESA MAX487ECPA MAX487ECSA MAX487EEPA MAX487EESA MAX488ECPA MAX488ECSA MAX488EEPA MAX488EESA TEMP. RANGE 0C to +70C 0C to +70C -40C to +85C -40C to +85C 0C to +70C 0C to +70C -40C to +85C -40C to +85C 0C to +70C 0C to +70C -40C to +85C -40C to +85C 0C to +70C 0C to +70C -40C to +85C -40C to +85C PIN-PACKAGE 8 Plastic DIP 8 SO 8 Plastic DIP 8 SO 8 Plastic DIP 8 SO 8 Plastic DIP 8 SO 8 Plastic DIP 8 SO 8 Plastic DIP 8 SO 8 Plastic DIP 8 SO 8 Plastic DIP 8 SO PART MAX489ECPD MAX489ECSD MAX489EEPD MAX489EESD MAX490ECPA MAX490ECSA MAX490EEPA MAX490EESA MAX491ECPD MAX491ECSD MAX491EEPD MAX491EESD MAX1487ECPA MAX1487ECSA MAX1487EEPA MAX1487EESA TEMP. RANGE 0C to +70C 0C to +70C -40C to +85C -40C to +85C 0C to +70C 0C to +70C -40C to +85C -40C to +85C 0C to +70C 0C to +70C -40C to +85C -40C to +85C 0C to +70C 0C to +70C -40C to +85C -40C to +85C PIN-PACKAGE 14 Plastic DIP 14 SO 14 Plastic DIP 14 SO 8 Plastic DIP 8 SO 8 Plastic DIP 8 SO 14 Plastic DIP 14 SO 14 Plastic DIP 14 SO 8 Plastic DIP 8 SO 8 Plastic DIP 8 SO
___________________Chip Information
TRANSISTOR COUNT: 295
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
16 __________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600 (c) 1996 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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