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MAX22025-MAX22028/
MAX22025F-MAX22028F
Compact, Isolated, Half-Duplex RS-485/RS-422
Transceivers with AutoDirection Control
General Description
Benefits and Features
The
MAX22025-MAX22028/MAX22025F-MAX22028F
compact isolated RS-485/RS-422 transceivers provide
3.5kVRMS of digital galvanic isolation between the cableside (RS-485/RS-422 driver/ receiver-side) and the UARTside of the device. Isolation improves communication by
breaking ground loops and reduces noise when there are
large differences in ground potential between ports. These
devices allow for robust communication up to 0.5Mbps or
16Mbps.
● High-Level Integration Reduces Overall Solution Size
• Fully Isolated Half-Duplex RS-485/RS-422
Transceivers
• Compact 8-Pin Wide Body SOIC Package (5.5mm
Creepage)
The
MAX22025-MAX22028/MAX22025F-MAX22028F
feature Maxim’s proprietary AutoDirection control making
these devices ideal for applications such as isolated
RS-485 ports, where the driver input is used in conjunction
with the driver-enable signal to drive the differential bus.
The
MAX22025/MAX22027/MAX22025F/MAX22027F
feature reduced slew rate drivers that minimize EMI and
reduce reflections caused by improper termination of cable allowing error-free transmission up to 0.5Mbps. The
MAX22026/MAX22028/MAX22026F/MAX22028F driver
outputs are not slew-rate limited, allowing transmit
speeds up to 16Mbps.
The receiver output of the MAX22025/MAX22026/
MAX22025F/MAX22026F does not follow (VA-VB) when
the device is in the driver-enabled state. The receiver
output on the MAX22027/MAX22028/MAX22027F/
MAX22028F always follows (VA-VB).
The driver outputs and receiver inputs are protected from
±10kV electrostatic discharge (ESD) to GNDB on the cable side, as specified by the Human Body Model (HBM).
The
MAX22025-MAX22028/MAX22025F-MAX22028F
are available in a compact 8-pin wide body SOIC package
and operate over the -40°C to +85°C temperature range.
● Integrated Protection Ensures Robust Communication
• ±10kV ESD (HBM) on Driver Outputs/Receiver
Inputs
• Failsafe Receiver Prevents Fault Transition on
• Receiver Input Short or Open Events (MAX22025FMAX22028F)
• Withstands 3.5kVRMS Isolation Voltage for 60
Seconds (VISO)
• Withstands 630VPEAK Maximum Repetitive PeakIsolation Voltage (VIORM)
• Continuously Withstands 445VRMS Maximum
Working-Isolation Voltage (VIOWM)
● Enables Flexible System Design
• 0.5Mbps Maximum Data Rate with Slew-Rate
Limited Driver (MAX22025/MAX22027/
MAX22025F/MAX22027F)
• 16Mbps Maximum Data Rate (MAX22026/
MAX22028/MAX22026F/MAX22028F)
• AutoDirection Eliminates the Need for DE and RE
Control Signals
Safety Regulatory Approvals
● UL According to UL1577
● cUL According to CSA Bulletin 5A
Applications
●
●
●
●
Utility Meters
Industrial Automation Equipment
Programmable Logic Controllers
HVAC
Ordering Information appears at end of data sheet.
19-100636; Rev 8; 3/22
© 2022 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners.
One Analog Way, Wilmington, MA 01887 U.S.A. | Tel: 781.329.4700 | © 2022 Analog Devices, Inc. All rights reserved.
MAX22025-MAX22028/
MAX22025F-MAX22028F
Compact, Isolated, Half-Duplex RS-485/RS-422
Transceivers with AutoDirection Control
Functional Diagram
VDDA
VDDB
MAX22025MAX22028/
MAX22025FMAX22028F
COM
STATE
MACHINE
www.analog.com
B
A
TXD
GNDA
VDT
RS-485
TRANSCEIVER
RXD
B
A
GNDB
Analog Devices | 2
MAX22025-MAX22028/
MAX22025F-MAX22028F
Compact, Isolated, Half-Duplex RS-485/RS-422
Transceivers with AutoDirection Control
TABLE OF CONTENTS
General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Benefits and Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Safety Regulatory Approvals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Functional Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
8 Wide SOIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
DC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Switching Electrical Characteristics (MAX22025/MAX22027/MAX22025F/MAX22027F) . . . . . . . . . . . . . . . . . . . . . . . . 9
Switching Electrical Characteristics (MAX22026/MAX22028/MAX22026F/MAX22028F) . . . . . . . . . . . . . . . . . . . . . . . . 9
Insulation Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Typical Operating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Pin Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
MAX22025-MAX22028F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Function Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Function Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Detailed Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Isolation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
AutoDirection Circuitry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Pullup and Pulldown Resistors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Receive State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Failsafe Receiver (MAX22025F-MAX22028F only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Receiver Output (RXD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
ESD Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
ESD Test Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Human Body Model (HBM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Typical Application Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Typical Application Circuit 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Typical Application Circuit 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
www.analog.com
Analog Devices | 3
MAX22025-MAX22028/
MAX22025F-MAX22028F
Compact, Isolated, Half-Duplex RS-485/RS-422
Transceivers with AutoDirection Control
LIST OF FIGURES
Figure 1. Driver DC Test Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 2. Driver Timing Test Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 3. Driver Propagation Delays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 4. Receiver Propagation Delay Test Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 5. Receiver Propagation Delays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Figure 6. Human Body ESD Test Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Figure 7. Human Body Current Waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
www.analog.com
Analog Devices | 4
MAX22025-MAX22028/
MAX22025F-MAX22028F
Compact, Isolated, Half-Duplex RS-485/RS-422
Transceivers with AutoDirection Control
LIST OF TABLES
Table 1. Safety Regulatory Approvals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
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Analog Devices | 5
MAX22025-MAX22028/
MAX22025F-MAX22028F
Compact, Isolated, Half-Duplex RS-485/RS-422
Transceivers with AutoDirection Control
Absolute Maximum Ratings
VDDA, TXD to GNDA ................................................ -0.3V to +6V
VDDB to GNDB ......................................................... -0.3V to +6V
RXD to GNDA........................................... -0.3V to (VDDA + 0.3V)
A, B to GNDB ............................................................ -8V to +13V
Short Circuit Duration (RXD to GNDA) ....................... Continuous
Short Circuit Duration (A, B to GNDB) ....................... Continuous
Continuous Power Dissipation (TA = +70°C)
8-pin Wide SOIC (derate 23mW/°C above +70°C) .....1847mW
Operating Temperature Range .............................-40°C to +85°C
Junction Temperature ....................................................... +150°C
Storage Temperature Range ..............................-65°C to +150°C
Lead Temperature (soldering, 10s)................................... +300ºC
Soldering Temperature (reflow) ........................................ +260°C
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.
Package Information
8 Wide SOIC
Package Code
W8MS+1
Outline Number
21-0262
Land Pattern Number
90-0258
THERMAL RESISTANCE, FOUR-LAYER BOARD
Junction to Ambient (θJA)
43.3°C/W
Junction to Case (θJC)
36.5°C/W
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages.
Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different
suffix character, but the drawing pertains to the package regardless of RoHS status.
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a
four-layer board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/
thermal-tutorial.
www.analog.com
Analog Devices | 6
MAX22025-MAX22028/
MAX22025F-MAX22028F
Compact, Isolated, Half-Duplex RS-485/RS-422
Transceivers with AutoDirection Control
DC Electrical Characteristics
(VDDA – VGNDA = 1.71V to 5.5V, VDDB – VGNDB = 4.75V to 5.25V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at
VDDA – VGNDA = 3.3V, VDDB – VGNDB = 5V, VGNDA = VGNDB, and TA = +25°C.) (Notes 1, 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
POWER
Supply Voltage
VDDA
1.71
5.5
VDDB
4.75
5.25
IDDA
VDDA = 3.3V, RXD is unconnected,
TXD = low, no bus load
0.39
0.7
IDDB
VDDB = 5V, RXD is unconnected,
TXD = low, no bus load
4.0
5.5
1.6
1.66
Supply Current
VDDA Undervoltage
Lockout Threshold
VUVLOA
VDDA Undervoltage
Lockout Threshold
Hysteresis
VUVHYSTA
VDDA rising
V
mA
1.5
45
V
mV
LOGIC INTERFACE (TXD, RXD)
Input High Voltage
Input Low Voltage
Input Hysteresis
VIH
VIL
TXD to GNDA
TXD to GNDA
2.25V ≤ VDDA ≤
5.5V
0.7 x
VDDA
1.71V ≤ VDDA <
2.25V
0.75 x
VDDA
V
2.25V ≤ VDDA ≤
5.5V
0.8
1.71V ≤ VDDA <
2.25V
0.7
V
VHYS
TXD to GNDA
410
mV
Input Capacitance
CIN
TXD, f = 1MHz
2
pF
Input Pullup Current
IPU
TXD
-10
Output Voltage High
VOH
RXD to GNDA, IOUT = -4mA
Output Voltage Low
VOL
RXD to GNDA, IOUT = 4mA
-5
-1.5
VDDA
-0.4
µA
V
0.4
V
DRIVER
RL = 100Ω, TXD = low, Figure 1
2.0
VDDB
RL = 54Ω, TXD = low, Figure 1
1.5
VDDB
-7V ≤ VCM ≤ +12V, TXD = low, Figure 1
1.5
5
Differential Driver
Output
|VOD|
Driver Common-Mode
Output Voltage
VOC
RL = 100Ω or 54Ω, TXD = low, Figure 1
Driver Disable
Threshold
VDT
TXD = low to high (Note 3)
Driver Short-Circuit
Output Current
IOSD
Driver Short-Circuit
Foldback Output Current
ISH
VDDB/2
V
3
V
0.6
1
V
GNDB ≤ VOUT ≤ +12V, output low
+50
+250
-7V ≤ VOUT ≤ VDDB, output high
-250
-50
(VDDB-1V) ≤ VOUT ≤ +12V, output low
+20
-7V ≤ VOUT ≤ VDDB, output high
-20
mA
mA
RECEIVER
Input Current (A and B)
www.analog.com
IA, I B
VDDB = GNDB or
5V, receive state
VIN = +12V
VIN = -7V
+250
-200
µA
Analog Devices | 7
MAX22025-MAX22028/
MAX22025F-MAX22028F
Compact, Isolated, Half-Duplex RS-485/RS-422
Transceivers with AutoDirection Control
DC Electrical Characteristics (continued)
(VDDA – VGNDA = 1.71V to 5.5V, VDDB – VGNDB = 4.75V to 5.25V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at
VDDA – VGNDA = 3.3V, VDDB – VGNDB = 5V, VGNDA = VGNDB, and TA = +25°C.) (Notes 1, 2)
PARAMETER
Receiver Differential
Threshold Voltage
SYMBOL
VTH
Receiver Input
Hysteresis
ΔVTH
Receiver Input
Resistance
RIN
CONDITIONS
-7V ≤ VCM ≤ +12V
MIN
TYP
MAX
MAX22025-MAX22
028
-200
+200
MAX22025FMAX22028F
-200
-50
UNITS
mV
VCM = 0V
25
mV
-7V ≤ VCM ≤ +12V, Receive state
60
kΩ
+135
°C
20
°C
THERMAL SHUTDOWN
Thermal Shutdown
Threshold
TSHDN
Thermal Shutdown
Hysteresis
TSHDN_ HYS
Temperature rising
PROTECTION
ESD Protection (A and
B Pins to GNDB)
Human Body Model
±10
kV
ESD Protection (A and
B Pins to GNDA) with
47pF Capacitor
Connected between
GNDA and GNDB
Human Body Model
±7
kV
ESD Protection (All
Other Pins)
Human Body Model
±4
kV
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Analog Devices | 8
MAX22025-MAX22028/
MAX22025F-MAX22028F
Compact, Isolated, Half-Duplex RS-485/RS-422
Transceivers with AutoDirection Control
Switching Electrical Characteristics (MAX22025/MAX22027/MAX22025F/MAX22027F)
(VDDA – VGNDA = 1.71V to 5.5V, VDDB – VGNDB = 4.75V to 5.25V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at
VDDA – VGNDA = 3.3V, VDDB – VGNDB = 5V, VGNDA = VGNDB, and TA = +25°C.) (Notes 1, 2)
PARAMETER
Common Mode
Transient Immunity
SYMBOL
CMTI
CONDITIONS
MIN
(Note 5)
TYP
MAX
50
UNITS
kV/μs
DRIVER
Driver Propagation
Delay
tDPLH, tDPHL
RL = 110Ω, CL = 50pF, Figure 2 and
Figure 3 (Note 4)
200
1000
ns
Driver Differential
Output Riseor Fall Time
tLH, tHL
RL = 110Ω, CL = 50pF, Figure 2 and
Figure 3 (Note 4)
200
900
ns
Maximum Data Rate
DRMAX
Driver Enable from
Power Up
tPORD
0.5
Mbps
100
150
μs
CL = 15pF, Figure 4 and Figure 5 (Note
4)
80
ns
CL = 15pF, Figure 5 (Note 4)
13
ns
RECEIVER
Receiver Propagation
Delay
tRPLH, tRPHL
Receiver Output Skew
|tRPLH - tRPHL|
tRSKEW
Maximum Data Rate
DRMAX
Receiver Enable from
Power Up
tPORR
16
Mbps
100
150
μs
Switching Electrical Characteristics (MAX22026/MAX22028/MAX22026F/MAX22028F)
(VDDA – VGNDA = 1.71V to 5.5V, VDDB – VGNDB = 4.75V to 5.25V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at
VDDA – VGNDA = 3.3V, VDDB – VGNDB = 5V, VGNDA = VGNDB, and TA = +25°C.) (Notes 1, 2)
PARAMETER
Common Mode
Transient Immunity
SYMBOL
CMTI
CONDITIONS
MIN
(Note 5)
TYP
MAX
50
UNITS
kV/μs
DRIVER
Driver Propagation
Delay
tDPLH, tDPHL
RL = 110Ω, CL = 50pF, Figure 2 and
Figure 3 (Note 4)
50
ns
Driver Differential
Output Riseor Fall Time
tLH, tHL
RL = 110Ω, CL = 50pF, Figure 2 and
Figure 3 (Note 4)
15
ns
Maximum Data Rate
DRMAX
Driver Enable from
Power Up
tPORD
16
Mbps
100
150
μs
CL = 15pF, Figure 4 and Figure 5
(Note 4)
80
ns
CL = 15pF, Figure 5 (Note 4)
13
ns
RECEIVER
Receiver Propagation
Delay
tRPLH, tRPHL
Receiver Output Skew
|tRPLH - tRPHL|
tRSKEW
Maximum Data Rate
DRMAX
Receiver Enable from
Power Up
tPORR
www.analog.com
16
Mbps
100
150
μs
Analog Devices | 9
MAX22025-MAX22028/
MAX22025F-MAX22028F
Compact, Isolated, Half-Duplex RS-485/RS-422
Transceivers with AutoDirection Control
Insulation Characteristics
PARAMETER
SYMBOL
Maximum Repetitive
Peak Withstand Voltage
VIORM
(Note 6)
630
VP
Maximum Working
Isolation Voltage
VIOWM
GNDA to GNDB continuous (Note 6)
445
VRMS
Maximum Transient
Isolation Voltage
VIOTM
5000
VP
Maximum Withstand
Isolation Voltage
VISO
3500
VRMS
10
kV
>109
Ω
2
pF
Maximum Surge
Isolation Voltage
VIOSM
CONDITIONS
GNDA to GNDB for 60s (Note 7)
Basic Insulation, 1.2/50μs pulse per
IEC61000-4-5
MIN
TYP
MAX
UNITS
Insulation Resistance
RS
TA = +150°C, VIO = 500V
Barrier Capacitance
Side A to Side B
CIO
GNDA to GNDB
Minimum Creepage
Distance
CPG
5.5
mm
Minimum Clearance
Distance
CLR
5.5
mm
0.015
mm
Internal Clearance
Comparitive Tracking
Resistance Index
Distance through insulation
CTI
>400
Climatic Category
40/125/
21
Pollution Degree
2
Note 1: All devices are 100% production tested at TA = +85°C. Specifications over temperature are guaranteed by design.
Note 2: All currents into the device are positive. All currents out of the device are negative. All voltages are referenced to their
respective ground (GNDA or GNDB), unless otherwise noted.
Note 3: This is the differential voltage from A to B that the driving device must see on the bus to disable its driver.
Note 4: Not production tested. Guaranteed by design.
Note 5: CMTI is the maximum sustainable common-mode voltage slew rate while maintaining the correct output states. CMTI applies
to both rising and falling common-mode voltage edges. Tested with the transient generator connected between GNDA and
GNDB. VCM = 1kV
Note 6: VIORM, VIOWM, and VISO are defined by the IEC 60747-5-5 standard..
Note 7: Product is qualified at VISO for 60 seconds. Not production tested.
www.analog.com
Analog Devices | 10
MAX22025-MAX22028/
MAX22025F-MAX22028F
Compact, Isolated, Half-Duplex RS-485/RS-422
Transceivers with AutoDirection Control
375Ω
A
A
RL
2
VOD
VOD
60Ω
+
-
VOC
RL
2
VCM
B
B
375Ω
(b)
(a)
Figure 1. Driver DC Test Load
TXD
A
VOD
CL
RL
B
Figure 2. Driver Timing Test Circuit
tLH ≤ 3ns, tHL ≤ 3ns
TXD
50%
VDDA
50%
GNDA
tDPLH
½ VO
tDPHL
B
A
½ VO
VO
VDIFF = (VA - VB)
80%
80%
20%
20%
+VO
0
VOD
tLH
-VO
tHL
tDSKEW = |tDPLH - tDPHL|
Figure 3. Driver Propagation Delays
A
ATE
R
VID
B
RECEIVER OUTPUT
CL
Figure 4. Receiver Propagation Delay Test Circuit
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Analog Devices | 11
MAX22025-MAX22028/
MAX22025F-MAX22028F
Compact, Isolated, Half-Duplex RS-485/RS-422
Transceivers with AutoDirection Control
tHL ≤ 3ns, tLH ≤ 3ns
A
+1V
B
-1V
tRPHL
RXD
tRPLH
VDDA
2
VDDA
2
VOH
VOL
tRSKEW = |tRPHL – tRPHL|
Figure 5. Receiver Propagation Delays
www.analog.com
Analog Devices | 12
MAX22025-MAX22028/
MAX22025F-MAX22028F
Compact, Isolated, Half-Duplex RS-485/RS-422
Transceivers with AutoDirection Control
Typical Operating Characteristics
(VDDA – VGNDA = 3.3V, VDDB – VGNDB = 5V, VGNDA = VGNDB, and TA = +25°C, unless otherwise noted.)
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Analog Devices | 13
MAX22025-MAX22028/
MAX22025F-MAX22028F
Compact, Isolated, Half-Duplex RS-485/RS-422
Transceivers with AutoDirection Control
Typical Operating Characteristics (continued)
(VDDA – VGNDA = 3.3V, VDDB – VGNDB = 5V, VGNDA = VGNDB, and TA = +25°C, unless otherwise noted.)
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Analog Devices | 14
MAX22025-MAX22028/
MAX22025F-MAX22028F
Compact, Isolated, Half-Duplex RS-485/RS-422
Transceivers with AutoDirection Control
Typical Operating Characteristics (continued)
(VDDA – VGNDA = 3.3V, VDDB – VGNDB = 5V, VGNDA = VGNDB, and TA = +25°C, unless otherwise noted.)
www.analog.com
Analog Devices | 15
MAX22025-MAX22028/
MAX22025F-MAX22028F
Compact, Isolated, Half-Duplex RS-485/RS-422
Transceivers with AutoDirection Control
Typical Operating Characteristics (continued)
(VDDA – VGNDA = 3.3V, VDDB – VGNDB = 5V, VGNDA = VGNDB, and TA = +25°C, unless otherwise noted.)
Pin Configuration
MAX22025-MAX22028F
TOP VIEW
RXD
1
TXD
2
VDDA
3
GNDA
4
+
MAX22025MAX22028/
MAX22025FMAX22028F
8
VDDB
7
B
6
A
5
GNDB
WIDE SOIC
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Analog Devices | 16
MAX22025-MAX22028/
MAX22025F-MAX22028F
Compact, Isolated, Half-Duplex RS-485/RS-422
Transceivers with AutoDirection Control
Pin Description
REF
SUPPLY
PIN
NAME
1
RXD
Receiver Data Output. See the Function Tables for more information.
GNDA
2
TXD
Driver Input. TXD is the input to the internal state machine that automatically
enables and disables the driver. See the Function Tables and AutoDirection
Circuitry sections for more information. TXD has an internal 5μA pullup to VDDA.
GNDA
3
VDDA
4
FUNCTION
UART/Logic-Side Power Input. Bypass VDDA to GNDA with both 0.1μF and 1μF
GNDA
capacitors as close to the device as possible.
GNDA
UART/Logic-Side Ground. GNDA is the ground reference for digital signals.
-
5
GNDB
Cable Side Ground. GNDB is the ground reference for the RS-485/RS-422 bus
signals.
-
6
A
Noninverting Driver Output/Receiver Input
GNDB
7
B
Inverting Driver Output/Receiver Input
GNDB
Cable Side Power Input. Bypass VDDB to GNDB with both 0.1μF and 1μF
capacitors as close to the device as possible.
GNDB
8
VDDB
Function Tables
Function Tables
TRANSMIT FUNCTIONALITY
TXD
(VA - VB)
PREVIOUS STATE
CURRENT STATE
A
B
0
X
X
Driver Enabled
0
1
1
(VA - VB) ≥ VDT
X
Receiver Enabled
High-Z
High-Z
1
(VA - VB) < VDT
Driver Enabled
Driver Enabled
1
0
Receiver Enabled
Receiver Enabled
High-Z
High-Z
X = Don’t care
RXD FUNCTIONALITY (STANDARD RECEIVER)
RXD
CURRENT STATE
Receiver Enabled
Driver Enabled
(VA - VB)
MAX22025/MAX22026
MAX22027/MAX22028
(VA - VB) ≥ +200mV
1
1
(VA - VB) ≤ -200mV
0
0
(VA - VB) ≥ +200mV
1
1
(VA - VB) ≤ -200mV
1
0
RXD FUNCTIONALITY (FAILSAFE RECEIVER)
CURRENT STATE
Receiver Enabled
Driver Enabled
www.analog.com
RXD
(VA - VB)
MAX22025F/MAX22026F
MAX22027F/MAX22028F
(VA - VB) ≥ -50mV
1
1
(VA - VB) ≤ -200mV
0
0
(VA - VB) ≥ -50mV
1
1
(VA - VB) ≤ -200mV
1
0
Analog Devices | 17
MAX22025-MAX22028/
MAX22025F-MAX22028F
Compact, Isolated, Half-Duplex RS-485/RS-422
Transceivers with AutoDirection Control
Detailed Description
The MAX22025-MAX22028/MAX22025F-MAX22028F isolated RS-485/RS-422 transceivers provide 3.5kVRMS (60s) of
galvanic isolation between the RS-485/RS-422 cable side of the transceiver and the UART side. These devices allow
up to 0.5Mbps (MAX22025/MAX22027/MAX22025F/MAX22027F) or 16Mbps (MAX22026/MAX22028/MAX22026F/
MAX22028F) communication across an isolation barrier when a large potential exists between grounds on each side of
the barrier.
Isolation
Data isolation is achieved using high-voltage capacitors that allow data transmission between the UART side and the
RS-485/RS-422 cable side of the transceiver.
The devices withstand differences in ground potential between the two power domains of up to 3.5kVRMS (VISO) for up
to 60s, and up to 445VRMS (VIOWM) for extended periods of time. See Table 1 for certification information.
Table 1. Safety Regulatory Approvals
UL
The MAX22025-MAX22028 and MAX22025F-MAX22028F are certified under UL1577. For more details, refer to File E351759.
Rated up to 3500VRMS for single protection.
cUL (Equivalent to CSA notice 5A)
The MAX22025-MAX22028 and MAX22025F-MAX22028F are certified up to 3500VRMS for single protection. For more details,
refer to File E351759.
AutoDirection Circuitry
Internal circuitry in the MAX22025-MAX22028/MAX22025F-MAX22028F, in conjunction with an external pullup resistor
on A and pulldown resistor on B (see Typical Application Circuit), acts to automatically disable or enable the driver and
the receiver to keep the bus in the correct state. This Auto Direction circuitry consists of a state machine and an additional
receive comparator that determine whether this device is trying to drive the bus or another node on the network is driving
the bus.
The internal state machine has two inputs:
● TXD
● The current state of (VA-VB), which is determined by a dedicated differential comparator.
The state machine also has two outputs:
● DRIVER_ENABLE—Internal signal that enables and disables the driver
● RECEIVER_ENABLE—Internal signal that is the inverse of the DRIVER_ENABLE signal.
When TXD is low, the device always drives the bus low. When TXD switches high, the device drives the bus for a short
time, then disables the driver and allows the external pullup/pulldown resistors to hold the bus in the high state. During
each low-to-high transition of TXD, the driver stays enabled until (VA-VB) ≥ VDT. The driver is then disabled and the
pullup/pulldown resistors hold the A and B lines in the correct state.
Pullup and Pulldown Resistors
The pullup and pulldown resistors on the A and B lines are required for proper operation of the device although their
exact value is not critical. They function to hold the bus in the high state following a low-to-high transition. Sizing
of these resistors is determined in the same way as when using any other RS-485 driver and depends on how the
line is terminated and how many nodes are on the bus. The most important factor when sizing these resistors is
to guarantee that the idle voltage on the bus (VA-VB) is greater than the receiver input threshold (+200mV for the
MAX22025-MAX22028, -50mV for the MAX22025F-MAX22028F) in order to remain compatible with standard RS-485
receiver thresholds.
www.analog.com
Analog Devices | 18
MAX22025-MAX22028/
MAX22025F-MAX22028F
Compact, Isolated, Half-Duplex RS-485/RS-422
Transceivers with AutoDirection Control
Receive State
When not transmitting data, the MAX22025-MAX22028/MAX22025F-MAX22028F require the TXD input be high to
remain in the receive state. A conventional RS-485 transceiver has DE and RE inputs that are used to enable and disable
the driver and receiver. However, the MAX22025-MAX22028/MAX22025F-MAX22028F do not have a DE input, and
instead use an internal state machine to enable and disable the drivers.
Failsafe Receiver (MAX22025F-MAX22028F only)
The MAX22025F-MAX22028F guarantee a logic high on the receiver output when the receiver inputs are shorted or
open, or when they are connected to a terminated transmission line with all drivers disabled. If the differential receiver
input voltage (VA - VB) is greater than or equal to -50mV, RXD is a logic-high.
Receiver Output (RXD)
The receiver output (RXD) of the MAX22025/MAX22026/MAX22025F/MAX22026F does not follow TXD when the device
is in the driver-enabled state. This allows for line interference detection by verifying that RXD remains high throughout
data transmission. On the MAX22027/MAX22028/MAX22027F/MAX22028F, the receiver output (RXD) always follows
(VA-VB).
ESD Protection
ESD protection structures are incorporated on all pins to protect against electrostatic discharge encountered during
handling and assembly. The driver outputs and receiver inputs of the devices have extra protection against static
electricity to both the UART side and cable side ground references. The ESD structures withstand high-ESD events
during normal operation and when powered down. After an ESD event, the devices keep working without latch-up or
damage. Bypass VDDA to GNDA and bypass VDDB to GNDB with 0.1μF and 1μF capacitors to ensure maximum ESD
protection.
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 (HBM)
Figure 6 shows the HBM test model, while Figure 7 shows the current waveform it generates when discharged in a
low-impedance state. This model consists of a 100pF capacitor charged to the ESD voltage of interest, which is then
discharged into the test device through a 1.5kΩ resistor.
RC
1MW
CHARGE CURRENTLIMIT RESISTOR
HIGHVOLTAGE
DC
SOURCE
CS
100pF
RD
1.5kW
DISCHARGE
RESISTANCE
STORAGE
CAPACITOR
DEVICE
UNDER
TEST
Figure 6. Human Body ESD Test Model
www.analog.com
Analog Devices | 19
MAX22025-MAX22028/
MAX22025F-MAX22028F
IP
Compact, Isolated, Half-Duplex RS-485/RS-422
Transceivers with AutoDirection Control
100%
90%
IR
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
AMPERES
36.8%
10%
0
0
tRL
TIME
tDL
Figure 7. Human Body Current Waveform
www.analog.com
Analog Devices | 20
MAX22025-MAX22028/
MAX22025F-MAX22028F
Compact, Isolated, Half-Duplex RS-485/RS-422
Transceivers with AutoDirection Control
Typical Application Circuits
Typical Application Circuit 1
5V
3.3V
5V
VDDB
VDDA
VDDB
RPU
VDDA
RPU
VCC
RXD
RXD
MAX22025- A
MAX22028/
MAX22025FMAX22028F
A
RT
RT
B
TX
RX
MAX22025MAX22028/
MAX22025FMAX22028F
B
TXD
TXD
RPD
1
TX
RPD
4
2
1
MICRCONTROLLER
MICRCONTROLLER
VCC
RX
3.3V
3
4
3
2
Typical Application Circuit 2
RS-485 TRANSCEIVER
TXD
1
A
A
B
B
2
2
n-1
B
A
B
RS-485 TRANSCEIVER
RXD
RE
TXD
DE
n-1
n
A
RS-485 TRANSCEIVER
MAX22025-MAX22028
MAX22025F-MAX22028F
INTEGRATED
ISOLATION
BARRIER
Master/
Slave
Master/
Slave
TXD
www.analog.com
Master/Slave
RS-485 TRANSCEIVER
RXD
VPU
VPU
Master/Slave
RXD
TXD
RXD
Analog Devices | 21
MAX22025-MAX22028/
MAX22025F-MAX22028F
Compact, Isolated, Half-Duplex RS-485/RS-422
Transceivers with AutoDirection Control
Ordering Information
TEMP RANGE
FAIL-SAFE
RECEIVER
RXD IN DRIVERENABLED STATE
DRIVER SPEED
(Mbps)
PIN-PACKAGE
MAX22025AWA+
-40°C to +85°C
NO
HIGH
0.5
8 Wide SOIC
MAX22025AWA+T
-40°C to +85°C
NO
HIGH
0.5
8 Wide SOIC
MAX22026AWA+
-40°C to +85°C
NO
HIGH
16
8 Wide SOIC
MAX22026AWA+T
-40°C to +85°C
NO
HIGH
16
8 Wide SOIC
MAX22027AWA+
-40°C to +85°C
NO
FOLLOWS (VA-VB)
0.5
8 Wide SOIC
MAX22027AWA+T
-40°C to +85°C
NO
FOLLOWS (VA-VB)
0.5
8 Wide SOIC
MAX22028AWA+
-40°C to +85°C
NO
FOLLOWS (VA-VB)
16
8 Wide SOIC
MAX22028AWA+T
-40°C to +85°C
NO
FOLLOWS (VA-VB)
16
8 Wide SOIC
MAX22025FAWA+
-40°C to +85°C
YES
HIGH
0.5
8 Wide SOIC
MAX22025FAWA+T
-40°C to +85°C
YES
HIGH
0.5
8 Wide SOIC
MAX22026FAWA+
-40°C to +85°C
YES
HIGH
16
8 Wide SOIC
MAX22026FAWA+T
-40°C to +85°C
YES
HIGH
16
8 Wide SOIC
MAX22027FAWA+
-40°C to +85°C
YES
FOLLOWS (VA-VB)
0.5
8 Wide SOIC
MAX22027FAWA+T
-40°C to +85°C
YES
FOLLOWS (VA-VB)
0.5
8 Wide SOIC
MAX22028FAWA+
-40°C to +85°C
YES
FOLLOWS (VA-VB)
16
8 Wide SOIC
MAX22028FAWA+T
-40°C to +85°C
YES
FOLLOWS (VA-VB)
16
8 Wide SOIC
PART
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
*Future product—contact factory for availability
www.analog.com
Analog Devices | 22
MAX22025-MAX22028/
MAX22025F-MAX22028F
Compact, Isolated, Half-Duplex RS-485/RS-422
Transceivers with AutoDirection Control
Revision History
REVISION
NUMBER
REVISION
DATE
0
8/19
Initial release
1
9/19
Updated the Electrical Characteristics section and added future product designation to
MAX22025AWA+ and MAX22025AWA+T in the Ordering Information table
2
11/19
Removed future product designation from MAX22025AWA+ and MAX22025AWA+T in the
Ordering Information table
3
2/20
3.1
PAGES
CHANGED
DESCRIPTION
—
3, 15
Updated the title, General Description, Benefits and Features, Functional Diagram, DC
Electrical Characteristics, Swtiching Electrical Characteristics, Pin Configuration, Functional
Tables, Detailed Description, AutoDirection Circuitry, Pullup and Pulldown Resistors,
Receive State, Receiver Output (RXD), and Typical Application Circuits sections; updated
TOC01–TOC14, TOC23–TOC32; added the Safety Regulatory Approvals table and
Failsafe Receiver (MAX22025F–MAX22028F) section; added MAX22025FAWA+,
MAX22025FAWA+T, MAX22026FAWA+, MAX22026FAWA+T, MAX22027FAWA+,
MAX22027FAWA+T, MAX22028FAWA+, and MAX22028FAWA+T as future parts to the
Ordering Information table
15
1–16
Corrected typo
1
15
4
4/20
Removed future product designation from MAX22025FAWA+ and MAX22025FAWA+T in
the Ordering Information table
5
3/21
Removed future product designation from MAX22028FAWA+ and MAX22028FAWA+T and
added a Fail-Safe Receiver column in the Ordering Information table
19
6
3/21
Removed future product designation from MAX22026FAWA+, MAX22026FAWA+T,
MAX22027FAWA+, and MAX22027FAWA+T in the Ordering Information table and updated
the Isolation and Receiver Output (RXD) sections
15, 16, 19
7
2/22
Removed future product designation from MAX22026AWA and MAX22026AWA+T in the
Ordering Information table
21
8
3/22
Removed future product designation from MAX22027AWA and MAX22027AWA+T in the
Ordering Information table
21
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is
assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may
result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of
their respective owners.
w w w . a n a l o g . c o m
Analog Devices | 23
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