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19-0742; Rev 0; 1/07
Half-Duplex RS-485/RS-422 Transceivers in DFN
General Description
The MAX13485E/MAX13486E +5V, half-duplex, 15kV ESD-protected RS-485 transceivers feature one driver and one receiver. These devices include fail-safe circuitry, guaranteeing a logic-high receiver output when receiver inputs are open or shorted. The receiver outputs a logichigh if all transmitters on a terminated bus are disabled (high impedance). The MAX13485E/MAX13486E include a hot-swap capability to eliminate false transitions on the bus during power-up or live-insertion. The MAX13485E features reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, allowing error-free transmission up to 500kbps. The MAX13486E driver slew rate is not limited, allowing transmit speeds up to 16Mbps. The MAX13485E/MAX13486E feature a 1/4-unit load receiver input impedance, allowing up to 128 transceivers on the bus. These devices are intended for half-duplex communications. All driver outputs are protected to 15kV ESD using the Human Body Model. The MAX13485E/ MAX13486E are available in 8-pin SO and space-saving 8-pin DFN packages. The devices operate over the extended -40C to +85C temperature range.
Features
o +5V Operation o True Fail-Safe Receiver While Maintaining EIA/TIA-485 Compatibility o Hot-Swappable for Telecom Applications o Enhanced Slew-Rate Limiting Facilitates ErrorFree Data Transmission (MAX13485E) o High-Speed Version (MAX13488E) Allows for Transmission Speeds Up to 16Mbps o Extended ESD Protection for RS-485/RS-422 I/O Pins 15kV Using Human Body Model o 1/4 Unit Load, Allowing Up to 128 Transceivers on the Bus o Available in Space-Saving 8-Pin DFN or Industry Standard 8-Pin SO Packages
MAX13485E/MAX13486E
Ordering Information/ Selector Guide
PART MAX13485EELA+T MAX13485EESA+ MAX13486EELA+T MAX13486EESA+ PINPACKAGE 8 DFN 8 SO 8 DFN 8 SO SLEW-RATE LIMITED Yes Yes No No PKG CODE L822-1 S8-2 L822-1 S8-2
Applications
Utility Meters Industrial Controls Industrial Motor Drives Automated HVAC Systems
+Denotes a lead-free package. Note: All devices are specified over the -40C to +85C operating temperature range.
Pin Configurations
TOP VIEW VCC 8 B 7 A 6 GND 5
MAX13485E MAX13486E
+ 1 RO 2 RE 3 DE 4 DI RO RE 1 2 + R 8 7 6 D 5 A GND B Rt Rt A 0.1F VCC B
DE
D
DI
DFN
+ RO RE 1 2 3 D R 8 7 6 5 VCC B A GND
DE 3 4 DI
R
RO
SO
MAX13485E MAX13486E
DE
RE
DI 4
SO
________________________________________________________________ Maxim Integrated Products
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Half-Duplex RS-485/RS-422 Transceivers in DFN MAX13485E/MAX13486E
ABSOLUTE MAXIMUM RATINGS
(All voltages referenced to GND.) VCC ........................................................................................+6V DE, RE, DI.................................................................-0.3V to +6V A, B ..............................................................................-8V to 13V Short-Circuit Duration (RO, A, B) to GND ..................Continuous Continuous Power Dissipation (TA = +70C) 8-Pin SO (derate 5.9mW/C above +70C)..................471mW 8-Pin DFN (derate 4.8mW/C above +70C) ..........380.6mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+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.
ELECTRICAL CHARACTERISTICS
(VCC = +5V 5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25C.) (Notes 1, 2)
PARAMETER DRIVER RDIFF = 100, Figure 1 Differential Driver Output Change in Magnitude of Differential Output Voltage Driver Common-Mode Output Voltage Change in Magnitude of Common-Mode Voltage Input-High Voltage Input-Low Voltage Input Current Driver Short-Circuit Output Current (Note 4) Driver Short-Circuit Foldback Output Current Note 3) RECEIVER Input Current (A and B) Receiver-Differential-Threshold Voltage Receiver Input Hysteresis Output-High Voltage IA, B VTH VTH VOH DE = GND, VCC = GND or +5V -7V < VCM < +12V VA + VB = 0V IO = -1.6mA, VA - VB > VTH VCC 1.5 VIN = +12V VIN = -7V -200 -200 25 -50 250 A mV mV V VOD RDIFF = 54, Figure 1 No load VOD VOC VOC VIH VIL IIN IOSD IOSDF RDIFF = 100 or 54, Figure 1 (Note 3) RDIFF = 100 or 54, Figure 1 RDIFF = 100 or 54, Figure 1 (Note 3) DI, DE, RE DI, DE, RE DI, DE, RE 0V < VOUT < +12V -7V < VOUT < 0V (VCC - 1V) < VOUT < +12V -7V < VOUT < 0V +50 -250 20 -20 2.0 0.8 1 +250 -50 VCC /2 2.0 1.5 VCC 0.2 3 0.2 V V V V V A mA mA VCC V SYMBOL CONDITIONS MIN TYP MAX UNITS
2
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Half-Duplex RS-485/RS-422 Transceivers in DFN
ELECTRICAL CHARACTERISTICS (continued)
MAX13485E/MAX13486E
(VCC = +5V 5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25C.) (Notes 1, 2)
PARAMETER Output-Low Voltage Tri-State Output Current at Receiver Receiver Input Resistance Receiver-Output Short-Circuit Current POWER SUPPLY Supply Voltage Supply Current Shutdown Supply Current ESD PROTECTION ESD Protection (A, B) ESD Protection (All Other Pins) Air Gap Discharge IEC61000-4-2 (MAX13485E) Human Body Model Human Body Model 15 15 2 kV kV VCC ICC ISHDN DE = 1, RE = 0, no load DE = 0, RE = 1 4.75 5.25 4.5 10 V mA A SYMBOL VOL IOZR RIN IOSR CONDITIONS IO = 1mA, VA - VB < -VTH 0V < VO < VCC -7V < VCM < +12V 0V < VRO < VCC 48 7 95 MIN TYP MAX 0.4 1 UNITS V A k mA
SWITCHING CHARACTERISTICS--MAX13485E
(VCC = +5V 5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25C.) (Note 1)
PARAMETER DRIVER Driver Propagation Delay Driver-Differential Output Rise or Fall Time Driver-Differential Output Skew |tDPLH - tDPHL| Maximum Data Rate Driver Enable to Output High Driver Enable to Output Low Driver Disable Time from High Driver Disable Time from Low Driver Enable from Shutdown to Output High Driver Enable from Shutdown to Output Low Time to Shutdown RECEIVER Receiver Propagation Delay Receiver Output Skew Maximum Data Rate tRPLH tRPHL tRSKEW CL = 15pF, Figures 6 and 7 CL = 15pF, Figure 7 500 80 80 13 ns ns kbps tDZH tDZL tDHZ tDLZ Figures 4 and 5 Figures 4 and 5 Figures 4 and 5 Figures 4 and 5 tDPLH tDPHL tHL tLH tDSKEW RDIFF = 54, CL = 50pF, Figures 2 and 3 RDIFF = 54, CL = 50pF, Figures 2 and 3 RDIFF = 54, CL = 50pF, Figures 2 and 3 500 2500 2500 100 100 5500 5500 50 340 700 200 200 250 250 1000 1000 900 900 140 ns ns ns kbps ns ns ns ns ns ns ns SYMBOL CONDITIONS MIN TYP MAX UNITS
tDZH(SHDN) Figures 4 and 5 tDZL(SHDN) Figures 4 and 5 tSHDN
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Half-Duplex RS-485/RS-422 Transceivers in DFN MAX13485E/MAX13486E
SWITCHING CHARACTERISTICS--MAX13485E (continued)
(VCC = +5V 5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25C.) (Note 1)
PARAMETER Receiver Enable to Output High Receiver Enable to Output Low Receiver Disable Time from High Receiver Disable Time from Low Receiver Enable from Shutdown to Output High Receiver Enable from Shutdown to Output Low Time to Shutdown SYMBOL tRZH tRZL tRHZ tRLZ Figure 8 Figure 8 Figure 8 Figure 8 CONDITIONS MIN TYP MAX 50 50 50 50 2200 2200 50 340 700 UNITS ns ns ns ns ns ns ns
tRZH(SHDN) Figure 8 tRZL(SHDN) Figure 8 tSHDN
SWITCHING CHARACTERISTICS--MAX13486E
(VCC = +5V 5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25C.) (Note 1)
PARAMETER DRIVER Driver Propagation Delay Driver Differential Output Rise or Fall Time Differential Driver Output Skew |tDPLH - tDPHL| Maximum Data Rate Driver Enable to Output High Driver Enable to Output Low Driver Disable Time from High Driver Disable Time from Low Driver Enable from Shutdown to Output High Driver Enable from Shutdown to Output Low Time to Shutdown RECEIVER Receiver Propagation Delay Receiver Output Skew Maximum Data Rate tRPLH tRPHL tRSKEW CL = 15pF, Figures 6 and 7 CL = 15pF, Figure 7 16 80 80 13 ns ns Mbps tDZH tDZL tDHZ tDLZ Figures 4 and 5 Figures 4 and 5 Figures 4 and 5 Figures 4 and 5 tDPLH tDPHL tHL tLH tDSKEW RDIFF = 54, CL = 50pF, Figures 2 and 3 RDIFF = 54, CL = 50pF, Figures 2 and 3 RDIFF = 54, CL = 50pF, Figures 2 and 3 16 50 50 50 50 2200 2200 50 340 700 50 50 15 15 8 ns ns ns Mbps ns ns ns ns ns ns ns SYMBOL CONDITIONS MIN TYP MAX UNITS
tDZH(SHDN) Figures 4 and 5 tDZL(SHDN) Figures 4 and 5 tSHDN
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Half-Duplex RS-485/RS-422 Transceivers in DFN
SWITCHING CHARACTERISTICS--MAX13486E (continued)
(VCC = +5V 5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25C.) (Note 1)
PARAMETER Receiver Enable to Output High Receiver Enable to Output Low Receiver Disable Time from High Receiver Disable Time from Low Receiver Enable from Shutdown to Output High Receiver Enable from Shutdown to Output Low Time to Shutdown SYMBOL tRZH tRZL tRHZ tRLZ Figure 8 Figure 8 Figure 8 Figure 8 CONDITIONS MIN TYP MAX 50 50 50 50 2200 2200 50 340 700 UNITS ns ns ns ns ns ns ns
MAX13485E/MAX13486E
tRZH(SHDN) Figure 8 tRZL(SHDN) Figure 8 tSHDN
Note 1: DFN devices production tested at +25C. Overtemperature limits are generated by design. Note 2: All currents into the device are positive. All currents out of the device are negative. All voltages referred to device ground, unless otherwise noted. Note 3: VOD and VOC are the changes in VOD and VOC when the DI input changes states. Note 4: The short-circuit output current applied to peak current just prior to foldback current limiting. The short-circuit foldback output current applies during current limiting to allow a recovery from bus contention.
Typical Operating Characteristics
(VCC = +5V, TA = +25C, unless otherwise noted.)
OUTPUT CURRENT vs. RECEIVER OUTPUT HIGH VOLTAGE
MAX13485-86E toc01 MAX13485-86E toc02
SUPPLY CURRENT vs. TEMPERATURE
4.0 NO LOAD 3.8 SUPPLY CURRENT (mA) 35
OUTPUT CURRENT vs. RECEIVER OUTPUT LOW VOLTAGE
MAX13485-86E toc03
60 50 OUTPUT CURRENT (mA) 40 30 20 10 0
28 OUTPUT CURRENT (mA)
3.6
21
3.4
14
3.2
7
3.0 -40 -15 10 35 60 85 TEMPERATURE (C)
0 0 1 2 3 4 5 OUTPUT HIGH VOLTAGE (V)
0
1
2
3
4
5
OUTPUT LOW VOLTAGE (V)
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Half-Duplex RS-485/RS-422 Transceivers in DFN MAX13485E/MAX13486E
Typical Operating Characteristics (continued)
(VCC = +5V, TA = +25C, unless otherwise noted.)
RECEIVER OUTPUT HIGH VOLTAGE vs. TEMPERATURE
MAX13485-86E toc04
RECEIVER OUTPUT LOW VOLTAGE vs. TEMPERATURE
IO = 1mA OUTPUT LOW VOLTAGE (V) 0.4
MAX13485-86E toc05
DIFFERENTIAL OUPUT CURRENT vs. DIFFERENTIAL OUTPUT VOLTAGE
MAX13485-86E toc06
5.4 IO = 1mA 5.2 OUTPUT HIGH VOLTAGE (V) 5.0 4.8 4.6 4.4 4.2 4.0 -40 -15 10 35 60
0.5
80
0.3
OUTPUT CURRENT (mA)
60
40
0.2
20
0.1
0 85 -40 -15 10 35 60 85 TEMPERATURE (C) TEMPERATURE (C)
0 0 1 2 3 4 5 OUTPUT VOLTAGE (V)
DRIVER-DIFFERENTIAL OUTPUT VOLTAGE vs. TEMPERATURE
MAX13485-86E toc07
OUTPUT CURRENT vs. TRANSMITTER OUTPUT HIGH VOLTAGE
MAX13485-86E toc08
OUTPUT CURRENT vs. TRANSMITTER OUTPUT LOW VOLTAGE
MAX13485-86E toc09
3.0 DIFFERENTIAL OUTPUT VOLTAGE (V) 2.5 2.0 1.5 1.0 0.5 0 -40 -15 10 35
120 100 OUTPUT CURRENT (mA) 80 60 40 20 0
RDIFF = 54
120 100 OUTPUT CURRENT (mA) 80 60 40 20 0
60
85
-7 -6 -5 -4 -3 -2 -1 0
1
2
3
4
5
0
2
4
6
8
10
12
TEMPERATURE (C)
OUTPUT HIGH VOLTAGE (V)
OUTPUT LOW VOLTAGE (V)
SHUTDOWN CURRENT vs. TEMPERATURE
MAX13485-86E toc10
DRIVER PROPAGATION vs. TEMPERATURE (MAX13485E)
MAX13485-86E toc11
DRIVER PROPAGATION DELAY vs. TEMPERATURE (MAX13486E)
MAX13485-86E toc12
10 9 SHUTDOWN CURRENT (A) 8 7 6 5 4 3 2 1 0 -40 -15 10 35 60
600 DRIVER PROPAGATION DELAY (ns) 550 500 450 400 350 300 tDPLH tDPHL
30 DRIVER PROPAGATION DELAY (ns) 25 20 15 10 5 tDPHL 0
tDPLH
85
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (C)
TEMPERATURE (C)
TEMPERATURE (C)
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Half-Duplex RS-485/RS-422 Transceivers in DFN MAX13485E/MAX13486E
Typical Operating Characteristics (continued)
(VCC = +5V, TA = +25C, unless otherwise noted.)
RECEIVER PROPAGATION vs. TEMPERATURE (MAX13485E)
MAX13485-86E toc13
RECEIVER PROPAGATION vs. TEMPERATURE (MAX13486E)
MAX13485-86E toc14
DRIVER PROPAGATION (500kbps) (MAX13485E)
MAX13485/86E toc15
80
40
60 tRPHL 40
RECEIVER PROPAGATION (ns)
PROPAGATION DELAY (ns)
30 tRPLH 20 tRPHL
DI 2V/div
20 tRPLH 0 -40 -15 10 35 60 85 TEMPERATURE (C)
10
A-B 5V/div
0 -40 -15 10 35 60 85 400ns/div TEMPERATURE (C)
DRIVER PROPAGATION (16Mbps) (MAX13486E)
MAX13485/86E toc16
RECEIVER PROPAGATION (16Mbps) (MAX13486E)
MAX13485/86E toc17
DI 2V/div
B 2V/div
A 2V/div
A-B 5V/div
RO 2V/div
10ns/div
10ns/div
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Half-Duplex RS-485/RS-422 Transceivers in DFN MAX13485E/MAX13486E
Test Circuits and Waveforms
A RDIFF 5V DE 2 DI VOD CL A VID B RDIFF B VOC RDIFF CL
2
Figure 1. Driver DC Test Load
Figure 2. Driver Timing Test Circuit
VCC DI 0 1.5V
f = 1MHz, tLH 3ns, tHL 3ns 1.5V 1/2 VO
tDPLH B A 1/2 VO VO VO VDIFF 0 -VO 10% tLH tDSKEW = |tDPLH - tDPHL| 90% VDIFF = V(A) - V(B)
tDPHL
90%
10% tHL
Figure 3. Driver Propagation Delays
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Half-Duplex RS-485/RS-422 Transceivers in DFN
Test Circuits and Waveforms (continued)
VCC DE 0 tDZL(SHDN),tDZL A, B 2.3V VOL A, B 2.3V 0 tDZH(SHDN),tDZH tDHZ OUTPUT NORMALLY LOW OUTPUT NORMALLY HIGH VOH + 0.5V VOL + 0.5V tDLZ 1.5V 1.5V
MAX13485E/MAX13486E
Figure 4. Driver Enable and Disable Times
500 OUTPUT UNDER TEST CL
S1
VCC
B ATE VID A R RECEIVER OUTPUT
S2
Figure 5. Driver-Enable and -Disable-Timing Test Load
Figure 6. Receiver Propagation Delay Test Circuit
A B
f = 1MHz, tLH 3ns, tHL 3ns
1V -1V
tRPHL VOH RO VOL 1.5V
tRPLH
1.5V tRSKEW = |tRPHL - tRPLH|
Figure 7. Receiver Propagation Delays
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Half-Duplex RS-485/RS-422 Transceivers in DFN MAX13485E/MAX13486E
Pin Description
PIN 1 2 NAME RO RE Receiver Output Receiver Output Enable. Drive RE low to enable RO. RO is high impedance when RE is high. Drive RE high and DE low to enter low-power shutdown mode. RE is a hot-swap input (see the Hot-Swap Capability section for more details). Driver Output Enable. Drive DE high to enable the driver outputs. These outputs are high-impedance when DE is low. Drive RE high and DE low to enter low-power shutdown mode. DE is a hot-swap input (see the Hot-Swap Capability section for more details). Driver Input. Drive DI low to force noninverting output low and inverting output high. Drive DI high to force noninverting output high and inverting output low (see the Function Tables). Ground Noninverting Receiver Input and Noninverting Driver Output Inverting Receiver Input and Inverting Driver Output Positive Supply, VCC = +5V 5%. Bypass VCC to GND with a 0.1F capacitor. FUNCTION
3
DE
4 5 6 7 8
DI GND A B VCC
Function Tables
TRANSMITTING INPUT RE X X 0 1 DE 1 1 0 0 DI 1 0 X X B 0 1 HIGH IMPEDANCE SHUTDOWN RECEIVING INPUT RE 0 0 0 1 1 DE X X X 1 0 A-B > -50mV < -200mV OPEN/SHORT X X OUTPUT RO 1 0 1 HIGH IMPEDANCE SHUTDOWN OUTPUT A 1 0 HIGH IMPEDANCE
X = Don't care, shutdown mode, driver, and receiver outputs are in high impedance.
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Half-Duplex RS-485/RS-422 Transceivers in DFN
Test Circuits and Waveforms (continued)
S1 +1V -1V S3 1k VID CL 15pF S2 VCC
MAX13485E/MAX13486E
GENERATOR
50
S1 OPEN S2 CLOSED S3 = +1V VCC/2 RE tRZH, tRZH(SHDN)
VCC
S1 CLOSED S2 OPEN S3 = -1V VCC/2
VCC
0
RE
0 tRZL, tRZL(SHDN)
RO VOH/2
VOH (VOL + VCC)/2 0 RO
VCC
VOL
S1 OPEN S2 CLOSED S3 = +1V VCC/2 RE tRHZ
VCC VCC/2 0 RE
S1 CLOSED S2 OPEN S3 = -1V
VCC
0 tRLZ VCC
RO 0.25V 0
VOH
RO
0.25V
VOL
Figure 8. Receiver Enable and Disable Times
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Half-Duplex RS-485/RS-422 Transceivers in DFN MAX13485E/MAX13486E
Detailed Description
The MAX13485E/MAX13486E half-duplex, high-speed transceivers for RS-485/RS-422 communication contain one driver and one receiver. These devices feature failsafe circuitry that guarantees a logic-high receiver output when receiver inputs are open or shorted, or when they are connected to a terminated transmission line with all drivers disabled (see the Fail-Safe section). The MAX13485E/MAX13486E also feature a hot-swap capability allowing line insertion without erroneous data transfer (see the Hot-Swap Capability section). The MAX13485E features reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, allowing error-free transmission up to 500kbps. The MAX13486E driver slew rate is not limited, making transmit speeds up to 16Mbps possible.
VCC 10s TIMER SR LATCH TIMER
5k DE 100A 500A M1 M2
Fail-Safe
The MAX13485E/MAX13486E guarantee a logic-high receiver output when the receiver inputs are shorted or open, or when they are connected to a terminated transmission line with all drivers disabled. This is done by setting the receiver input threshold between -50mV and -200mV. If the differential receiver input voltage (A - B) is greater than or equal to -50mV, RO is logic-high. If (A - B) is less than or equal to -200mV, RO is logic-low. In the case of a terminated bus with all transmitters disabled, the receiver's differential input voltage is pulled to 0V by the termination. With the receiver thresholds of the MAX13485E/MAX13486E, this results is a logic-high with a 50mV minimum noise margin. Unlike previous fail-safe devices, the -50mV to -200mV threshold complies with the 200mV EIA/TIA-485 standard.
DE (HOT SWAP)
Figure 9. Simplified Structure of the Driver Enable Pin (DE)
When VCC rises, an internal pulldown circuit holds DE low and RE high. After the initial power-up sequence, the pulldown circuit becomes transparent, resetting the hot-swap tolerable input. Hot-Swap Input Circuitry The enable inputs feature hot-swap capability. At the input there are two nMOS devices, M1 and M2 (Figure 9). When VCC ramps from zero, an internal 7s timer turns on M2 and sets the SR latch, which also turns on M1. Transistors M2, a 1.5mA current sink, and M1, a 500A current sink, pull DE to GND through a 5k resistor. M2 is designed to pull DE to the disabled state against an external parasitic capacitance up to 100pF that can drive DE high. After 7s, the timer deactivates M2 while M1 remains on, holding DE low against tristate leakages that can drive DE high. M1 remains on until an external source overcomes the required input current. At this time, the SR latch resets and M1 turns off. When M1 turns off, DE reverts to a standard highimpedance CMOS input. Whenever VCC drops below 1V, the hot-swap input is reset. For RE there is a complementary circuit employing two pMOS devices pulling RE to VCC.
Hot-Swap Capability
Hot-Swap Inputs When circuit boards are inserted into a hot or powered backplane, differential disturbances to the data bus can lead to data errors. Upon initial circuit-board insertion, the data communication processor undergoes its own power-up sequence. During this period, the processor's logic-output drivers are high impedance and are unable to drive the DE and RE inputs of these devices to a defined logic level. Leakage currents up to 10A from the high impedance state of the processor's logic drivers could cause standard CMOS enable inputs of a transceiver to drift to an incorrect logic level. Additionally, parasitic circuit-board capacitance could cause coupling of VCC or GND to the enable inputs. Without the hot-swap capability, these factors could improperly enable the transceiver's driver or receiver.
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Half-Duplex RS-485/RS-422 Transceivers in DFN MAX13485E/MAX13486E
RC 1M CHARGE-CURRENT LIMIT RESISTOR HIGHVOLTAGE DC SOURCE RD 1500 DISCHARGE RESISTANCE DEVICE UNDER TEST HIGHVOLTAGE DC SOURCE RC 50M TO 100M CHARGE-CURRENT LIMIT RESISTOR RD 330 DISCHARGE RESISTANCE DEVICE UNDER TEST
Cs 100pF
STORAGE CAPACITOR
Cs 150pF
STORAGE CAPACITOR
Figure 10a. Human Body ESD Test Model
Figure 10c. ICE 61000-4-2 ESD Test Model
I 100% 90% IPEAK
IP 100% 90% AMPS 36.8% 10% 0 0 tRL TIME
Ir
PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE)
10% tr = 0.7ns TO 1ns tDL CURRENT WAVEFORM 30ns 60ns t
Figure 10b. Human Body Current Waveform
Figure 10d. IEC 61000-4-2 ESD Generator Current Waveform
+15V 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 of the MAX13485E/MAX13486E have extra protection against static electricity. Maxim's engineers have 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, the MAX13485E/MAX13486E keep working without latchup or damage. ESD protection can be tested in various ways. The transmitter outputs and receiver inputs of the MAX13485E/ MAX13486E are characterized for protection to the following limits: * 15kV using the Human Body Model * 15kV using the Air Gap Discharge Method specified in IEC 61000-4-2 (MAX13485E only)
ESD Test Conditions ESD performance depends on a variety of conditions. Contact Maxim for a reliability report that documents test setup, test methodology, and test results. Human Body Model Figure 10a shows the Human Body Model, and Figure 10b 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. IEC 61000-4-2 The IEC 61000-4-2 standard covers ESD testing and performance of finished equipment. However, it does not specifically refer to integrated circuits. The MAX13485E/MAX13486E help equipment designs to meet IEC 61000-4-2, without the need for additional ESD-protection components. The major difference between tests done using the Human Body Model and IEC 61000-4-2 is higher peak current in IEC 61000-4-2 because series resistance is lower in the IEC 61000-4-2 model. Hence, the ESD
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Half-Duplex RS-485/RS-422 Transceivers in DFN MAX13485E/MAX13486E
DI DE RO RE
D
Rt
Rt
D
DI DE
R
R
RO RE
MAX13485E MAX13486E
D
R
R
D
DI
DE
RO
RE
DI
DE
RO
RE
Figure 11. Typical Half-Duplex RS-485 Network
withstand voltage measured to IEC 61000-4-2 is generally lower than that measured using the Human Body Model. Figure 10c shows the IEC 61000-4-2 model, and Figure 10d shows the current waveform for the IEC 61000-4-2 ESD Contact Discharge test. Machine Model The machine model for ESD tests all pins using a 200pF storage capacitor and zero discharge resistance. The objective is to emulate the stress caused when I/O pins are contacted by handling equipment during test and assembly. Of course, all pins require this protection, not just RS-485 inputs and outputs. 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.
Low-Power Shutdown Mode
Low-power shutdown mode is initiated by bringing both RE high and DE low. In shutdown, the devices draw a maximum of 10A of supply current. RE and DE can be driven simultaneously. The devices 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 700ns, the devices are guaranteed to enter shutdown. Enable times tZH and tZL (see the Switching Characteristics) assume the devices were not in a low-power shutdown state. Enable times t ZH(SHDN) and t ZL(SHDN) assume the devices were in shutdown state. It takes drivers and receivers longer to become enabled from lowpower shutdown mode (tZH(SHDN), tZL(SHDN)) than from driver-/receiver-disable mode (tZH, tZL).
Applications Information
128 Transceivers on the Bus
The standard RS-485 receiver input impedance is 12k (1-unit load), and the standard driver can drive up to 32-unit loads. The MAX13485E/MAX13486E have a 1/4unit load receiver input impedance (48k), allowing up to 128 transceivers to be connected in parallel on one communication line. Any combination of these devices, as well as other RS-485 transceivers with a total of 32unit loads or fewer, can be connected to the line.
Line Length
The RS-485/RS-422 standard covers line lengths up to 4000ft.
Typical Applications
The MAX13485E/MAX13486E transceivers are designed for half-duplex, bidirectional data communications on multipoint bus transmission lines. Figure 11 shows typical network applications circuits. To minimize reflections, terminate the line at both ends in its characteristic impedance, and keep stub lengths off the main line as short as possible. The slew-rate-limited MAX13485E is more tolerant of imperfect termination.
Reduced EMI and Reflections
The MAX13485E features reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, allowing error-free data transmission up to 500kbps.
14
Chip Information
PROCESS: BiCMOS
______________________________________________________________________________________
Half-Duplex RS-485/RS-422 Transceivers in DFN
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
MAX13485E/MAX13486E
INCHES DIM A A1 B C e E H L MAX MIN 0.069 0.053 0.010 0.004 0.014 0.019 0.007 0.010 0.050 BSC 0.150 0.157 0.228 0.244 0.016 0.050
MILLIMETERS MAX MIN 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 1.27 BSC 3.80 4.00 5.80 6.20 0.40 1.27
N
E
H
VARIATIONS:
1
INCHES
MILLIMETERS MIN 4.80 8.55 9.80 MAX 5.00 8.75 10.00 N MS012 8 AA 14 AB 16 AC
TOP VIEW
DIM D D D
MIN 0.189 0.337 0.386
MAX 0.197 0.344 0.394
D C
A e B A1
0 -8 L
FRONT VIEW
SIDE VIEW
PROPRIETARY INFORMATION TITLE:
PACKAGE OUTLINE, .150" SOIC
APPROVAL DOCUMENT CONTROL NO. REV.
21-0041
B
1 1
______________________________________________________________________________________
SOICN .EPS
15
Half-Duplex RS-485/RS-422 Transceivers in DFN MAX13485E/MAX13486E
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
6, 8, 10L UDFN.EPS
A
1 2
D
A
e
b
N
XXXX XXXX XXXX
SOLDER MASK COVERAGE
E
PIN 1 0.10x45
L L1
PIN 1 INDEX AREA SAMPLE MARKING 7 1 A A
(N/2 -1) x e)
C L
C L
b A A2 A1
L e
EVEN TERMINAL
L e
ODD TERMINAL
PACKAGE OUTLINE, 6, 8, 10L uDFN, 2x2x0.80 mm
-DRAWING NOT TO SCALE-
21-0164
COMMON DIMENSIONS SYMBOL A A1 A2 D E L L1 MIN. 0.70 0.15 0.020 1.95 1.95 0.30 NOM. 0.75 0.20 0.025 2.00 2.00 0.40 0.10 REF. MAX. 0.80 0.25 0.035 2.05 2.05 0.50
PACKAGE VARIATIONS PKG. CODE L622-1 L822-1 L1022-1 N 6 8 10 e 0.65 BSC 0.50 BSC 0.40 BSC b 0.30-0.05 0.25-0.05 0.20-0.03 (N/2 -1) x e 1.30 REF. 1.50 REF. 1.60 REF.
PACKAGE OUTLINE, 6, 8, 10L uDFN, 2x2x0.80 mm
-DRAWING NOT TO SCALE-
21-0164
A
2 2
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) 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.
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