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MAX33070E/MAX33071E/
MAX33074E
+3.3V and +5.0V, RS-485 Half-Duplex
Transceiver with ±65V Fault Protection,
±40V CMR, and ±40kV ESD
General Description
The MAX33070E/MAX33071E/MAX33074E are a family
of fault-protected RS-485/RS-422 transceivers with high
±65V protection for overvoltage conditions on the
communication bus lines, ensuring robust protection in
harsh industrial environments. All devices have ±40V of
common-mode range (CMR) within VCCH (+4.5V to
+5.5V), exceeding the RS-485 standard of -7V to +12V,
making them suitable for electrically noisy environments
where different systems have shifting ground levels
relative to each other. They also incorporate a high ESD
protection circuit capable of protecting against ±40kV of
ESD Human Body Model (HBM) for driver outputs and
receiver inputs (A and B data lines). Each device
contains one driver and one receiver and operates over
the +3V to +5.5V supply range, making it convenient for
designers to use one part with either +3.3V or +5V
supply voltages across multiple end equipment.
These devices feature a receiver enable ( ) input that
allows for a low-current shutdown state. The
MAX33070E features slew-rate-limited outputs for data
rates up to 500kbps. For applications requiring higher
bandwidth, the MAX33071E is rated up to 2Mbps, and
the MAX33074E up to 20Mbps. These transceivers are
optimized for robust communication in noisy
environments. A true fail-safe feature guarantees a
logic-high on the receiver output when the inputs are
open or shorted. Driver outputs are protected against
short-circuit conditions. The receivers feature a 1/8-unit
load input impedance, allowing up to 256 transceivers
on a bus.
Benefits and Features
• Integrated Protection for Robust Communication
• Protection on Driver Outputs/Receiver Inputs
•
•
•
•
•
•
(A, B Data Lines)
- ±65V Fault Protection Range on Driver
Outputs/Receiver Inputs
- ±40V Common-Mode Range on Driver
Outputs/Receiver Inputs
- ±40kV Human Body Model (JEDEC JS-0012017) ESD Protection
- ±15kV Air-Gap Discharge (IEC 61000-4-2)
ESD Protection
- ±10kV Contact Discharge (IEC 61000-4-2)
ESD Protection
Hot-Swap Protection
Short-Circuit Protection
Thermal Shutdown
True Fail-Safe Guarantees Known Receiver
Output State
Wide Operating Temperature Range from
-40°C to +125°C
High-Performance Transceiver Enables Flexible
Designs
• Compliant with RS-485 EIA/TIA-485 Standard
• 500kbps (MAX33070E), 2Mbps (MAX33071E),
20Mbps (MAX33074E) Maximum Data Rate
• 3.3V and 5.0V Supply Voltage
• 1/8 Unit Load for up to 256 Devices on the Bus
Ordering Information appears at end of data sheet.
The MAX33070E/MAX33071E are available in an 8-pin
SO, and the MAX33074E is available in an 8-pin SO with
an exposed pad. All three devices operate over the
-40°C to +125°C temperature range.
Applications
•
•
•
•
•
•
Industrial Automation Equipment
Home and Building Automation
Agriculture and Heavy Machinery
Power Supply and UPS
Elevator Control
Motion Controllers
www.maximintegrated.com
19-100900; Rev 0; 1/21
MAX33070E/MAX33071E/
MAX33074E
+3.3V and +5.0V, RS-485 Half-Duplex
Transceiver with ±65V Fault Protection,
±40V CMR, and ±40kV ESD
Simplified Block Diagram
VCC
MAX33070E
MAX33071E
MAX33074E
R
RE
SHUTDOWN
DE
DI
PROTECTION
RO
B
A
D
GND
www.maximintegrated.com
19-100900; Rev 0; 12/20
Maxim Integrated | 2
MAX33070E/MAX33071E/
MAX33074E
+3.3V and +5.0V, RS-485 Half-Duplex
Transceiver with ±65V Fault Protection,
±40V CMR, and ±40kV ESD
Absolute Maximum Ratings
VCC......................................................................... -0.3V to +6V
RO .............................................................. -0.3V to VCC + 0.3V
DE, DI,
............................................................. -0.3V to +6V
A, B (Continuous) ................................................. -70V to +70V
Short-Circuit Duration (RO, A, B) ............................ Continuous
Continuous Power Dissipation
__8-Pin SO +70°C (derate 7.6mW/°C above +70°C) 606.1mW
__8-Pin SO-EP +70°C (derate 24.4mW/°C above +70°C)
................................................................................. 1951.2mW
__Operating Temperature Range................... -40°C to +125°C
__Junction Temperature ................................................ +150°C
__Storage Temperature Range ...................... -65°C to +150°C
__Lead Temperature (soldering, 10s) ........................... +300°C
__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
SO
Package Code
S8+4
Outline Number
21-0041
Land Pattern Number
90-0096
Thermal Resistance, Four-Layer Board
Junction to Ambient (θJA)
132°C/W
Junction to Case (θJC)
38°C/W
SO-EP
Package Code
S8E+14C
Outline Number
21-0111
Land Pattern Number
90-0151
Thermal Resistance, Four-Layer Board
Junction to Ambient (θJA)
41°C/W
Junction to Case (θJC)
7°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 fourlayer board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
www.maximintegrated.com
Maxim Integrated | 3
MAX33070E/MAX33071E/
MAX33074E
+3.3V and +5.0V, RS-485 Half-Duplex
Transceiver with ±65V Fault Protection,
±40V CMR, and ±40kV ESD
Electrical Characteristics
(VCC = 3.0V to 3.6V and VCC = 4.5V to 5.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = 5.0V and TA =
+25°C. (Note 1))
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
POWER
Supply Voltage
Supply Current
Shutdown Supply
Current
VCCL
Low range
3
3.6
VCCH
High range
4.5
5.5
ICC
ISHDN
DE = high,
no switching
DE = 0V,
= low, no load,
= VCC
V
6
mA
4
μA
DRIVER
Differential Driver
Output
|VOD|
Figure 1a, RL = 54Ω
1.5
Figure 1a, RL = 100Ω
2.0
Figure 1b
1.5
Figure 1b, VCC = VCCL
-25
+25
Figure 1b, VCC = VCCH
-40
+40
+0.2
V
3
V
+0.1
V
V
External CommonMode Voltage
VCM
Change in Magnitude
of Differential Driver
Output Voltage
∆VOD
RL = 54Ω or 100Ω, Figure 1a
(Note 2)
-0.2
Driver CommonMode Output Voltage
VOC
RL = 54Ω or 100Ω, Figure 1a
1
Change in Magnitude
of Common-Mode
Voltage
∆VOC
RL = 54Ω or 100Ω, Figure 1a
(Note 2)
-0.1
Single-Ended Driver
Output Voltage High
VOH
A or B output, output is high,
ISOURCE = 3mA
2.4
Single-Ended Driver
Output Voltage Low
VOL
A or B output, output is low,
ISINK = 3mA
0.2
V
Driver Short-Circuit
Output Current
ISC_DR
-65V ≤ (VA or VB) < 0V or VCC < (VA
or VB) ≤ +65V (Note 3)
450
mA
0V ≤ (VA or VB) ≤ VCC
450
mA
Average Driver ShortCircuit Output Current
IAVG_SCDR
VCC/2
VCC 0.2
V
V
RECEIVER
VCM = +40V
410
Input Current (A, B)
IA, IB
DE = low, 0V ≤
VCC ≤ 5.5V
Receiver Input
Resistance
RIN
Over VCM range
96
Common-Mode
Voltage Range
VCM
VCC = VCCL
-25
+25
VCC = VCCH
-40
+40
www.maximintegrated.com
VCM = -40V
-424
μA
kΩ
V
Maxim Integrated | 4
MAX33070E/MAX33071E/
MAX33074E
+3.3V and +5.0V, RS-485 Half-Duplex
Transceiver with ±65V Fault Protection,
±40V CMR, and ±40kV ESD
(VCC = 3.0V to 3.6V and VCC = 4.5V to 5.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = 5.0V and TA =
+25°C. (Note 1))
PARAMETER
SYMBOL
CONDITIONS
Receiver Differential
Threshold Voltage
Rising
VTLH
Over VCM range
Receiver Differential
Threshold Voltage
Falling
VTHL
Over VCM range
Receiver Input
Hysteresis
∆VTH
Differential Input
Capacitance
CA_B
Measured between A and B,
f = 1MHz
RO Output LogicHigh Voltage
VOH
ISOURCE = 3mA, (VA - VB) ≥ -50mV
RO Output Logic-Low
Voltage
VOL
ISINK = 3mA, (VA - VB) ≤ -200mV
RO Leakage Current
IOZR
MIN
TYP
MAX
UNITS
-50
mV
-200
mV
100
mV
50
pF
LOGIC OUTPUT
RO Short-Circuit
Current
LOGIC INPUTS (DE, DI,
Ι IOSR Ι
0 ≤ (VA - VB) ≤
VCC
V
-1
VCC = VCCL
90
VCC = VCCH
190
0.4
V
+1
μA
mA
)
Input Logic-High
Voltage
VIH
Input Logic-Low
Voltage
VIL
Input Hysteresis
VHYS
Input Leakage
Current
= VIH, 0V ≤ VRO ≤ VCC
VCC 0.4
2
V
0.8
100
V
mV
After first transition of DE and
-1
+1
μA
RIN_FT
DE
1
10
kΩ
Thermal Shutdown
Threshold
TSHDN
Temperature rising
Thermal Shutdown
Hysteresis
THYST
Input Impedance on
First Transition
IIN
PROTECTION
ESD Protection (A, B
Pins to GND)
ESD Protection (All
Other Pins)
www.maximintegrated.com
+160
°C
12
°C
Human Body Model (JEDEC JS-0012017)
±40
IEC 61000-4-2 Contact Discharge
±10
IEC 61000-4-2 Air Gap
±15
Human Body Model
±4000
Charge Device Model
±2000
kV
V
Maxim Integrated | 5
MAX33070E/MAX33071E/
MAX33074E
+3.3V and +5.0V, RS-485 Half-Duplex
Transceiver with ±65V Fault Protection,
±40V CMR, and ±40kV ESD
(VCC = 3.0V to 3.6V and VCC = 4.5V to 5.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = 5.0V and TA =
+25°C. (Note 1))
PARAMETER
SYMBOL
Fault Protection
Range (A, B Pins to
GND)
CONDITIONS
MIN
TYP
MAX
A, B independently or simultaneously
-65
+65
A and B opposite polarity from
separate supplies simultaneously
-65
+65
UNITS
V
SWITCHING
DRIVER (Note 4) (Note 5)
Driver Propagation
Delay
RL = 54Ω, CL =
50pF (Figure 2)
(Figure 3)
MAX33070E
50
1000
tDPLH, tDPHL
MAX33071E/74E
25
50
Differential Driver
Output Skew |tDPLH tDPHL|
RL = 54Ω, CL =
50pF (Figure 2)
(Figure 3)
MAX33070E
10
140
tDSKEW
MAX33071E/74E
2
10
Driver Differential
Output Rise or Fall
Time
RL = 54Ω, CL =
50pF (Figure 2)
(Figure 3)
MAX33070E
30
600
tLH, tHL
MAX33071E/74E
8
15
DRMAX
RL = 54Ω, CL =
50pF
Maximum Data Rate
MAX33070E
0.5
MAX33071E
2
MAX33074E
20
ns
ns
ns
Mbps
RL = 110Ω, CL =
50pF (Figure 4)
(Figure 5)
MAX33070E
500
tDZH, tDZL
MAX33071E/74E
400
Driver Enable Time
tD
-40V ≤ VCM ≤
+40V, Figure 1b
MAX33070E
3.5
Driver Disable Time
from Output Low or
Output High
tDLZ, tDHZ
RL = 110Ω, CL = 50pF (Figure 4)
(Figure 5)
500
ns
Driver Enable Time
from Shutdown to
Output High
tDZH_SHDN
RL = 110Ω, CL = 50pF (Figure 4)
(Figure 6)
170
μs
Driver Enable Time
from Shutdown to
Output Low
tDZL_SHDN
RL = 110Ω, CL = 50pF (Figure 4)
(Figure 6)
170
μs
Time to Shutdown
tSHDN
800
ns
Driver Enable to
Output High or
Output Low
MAX33071E/74E
(Note 6)
ns
μs
1
50
RECEIVER (Note 4) (Note 5)
Receiver Propagation
Delay
Receiver Output
Skew
www.maximintegrated.com
CL = 15pF
(Figure 6)
(Figure 7)
MAX33070E
130
200
tRPLH, tRPHL
MAX33071E/74E
55
75
CL = 15pF
(Figure 6)
(Figure 7)
MAX33070E
2
30
tRSKEW
MAX33071E/74E
1
10
ns
ns
Maxim Integrated | 6
MAX33070E/MAX33071E/
MAX33074E
+3.3V and +5.0V, RS-485 Half-Duplex
Transceiver with ±65V Fault Protection,
±40V CMR, and ±40kV ESD
(VCC = 3.0V to 3.6V and VCC = 4.5V to 5.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = 5.0V and TA =
+25°C. (Note 1))
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Receiver Enable to
Output High
tRZH
RL = 1kΩ, CL = 15pF, DE = VIH
(Figure 8)
400
ns
Receiver Enable to
Output Low
tRZL
RL = 1kΩ, CL = 15pF, DE = VIH
(Figure 8)
400
ns
Receiver Disable
Time from Low
tRLZ
RL = 1kΩ, CL = 15pF, DE = VIH
(Figure 8)
400
ns
Receiver Disable
Time from High
tRHZ
RL = 1kΩ, CL = 15pF, DE = VIH
(Figure 8)
400
ns
Receiver Enable from
Shutdown to Output
High
tRLZ_SHDN
RL = 1kΩ, CL = 15pF (Figure 8)
170
μs
Receiver Enable from
Shutdown to Output
Low
tRHZ_SHDN
RL = 1kΩ, CL = 15pF (Figure 8)
170
μs
800
ns
Time to Shutdown
tDSHDN
(Note 6)
50
Note 1: All devices are 100% production tested at TA = +25°C. Specifications over temperature are guaranteed by
design.
Note 2: ΔVOD and ΔVOC are the changes in VOD and VOC, respectively, when DI changes state.
Note 3: The short-circuit current is 450mA (max) for a short period (30μs, typ). If the short circuit persists, the outputs
are then set to high impedance for 300ms (typ).
Note 4: Capacitive load includes test probe and fixture capacitance.
Note 5: Guaranteed by design. Not production tested.
Note 6: Shutdown is enabled when RE is high and DE is low. If the enable inputs are in this state for less than 50ns,
the device is guaranteed not to enter shutdown. If the enable inputs are held in this state for at least 800ns,
the device is guaranteed to have entered shutdown.
375Ω
A
A
RL
2
VOD
VOD
RL
2
60Ω
+ VCM
-
VOC
B
B
375Ω
(a)
(b)
Figure 1. Driver DC Test Load
www.maximintegrated.com
Maxim Integrated | 7
MAX33070E/MAX33071E/
MAX33074E
+3.3V and +5.0V, RS-485 Half-Duplex
Transceiver with ±65V Fault Protection,
±40V CMR, and ±40kV ESD
A
DI
VOD
B
RL
CL
Figure 2. Driver Timer Test Circuit
tLH ≤ 3ns, tHL ≤ 3ns
VCC
50%
DI
50%
GND
½ VO
tDPHL
tDPLH
B
A
½ VO
VO
VDIFF = VA - VB
VO
80%
80%
0
VDIFF
20%
20%
tLH
-VO
tHL
tDSKEW = |tDPLH - tDPHL|
Figure 3. Driver Propagation Delays
A
GND OR VCC
DI
S1
D
B
DE
CL =
50pF
VCC
OUT
RL = 110Ω
DE
tDZH
OUT
GENERATOR
50Ω
50%
250mV
50%
tDHZ
GND
VOH
GND
Figure 4. Driver Enable and Disable Times (tDHZ, tDZH)
www.maximintegrated.com
Maxim Integrated | 8
MAX33070E/MAX33071E/
MAX33074E
+3.3V and +5.0V, RS-485 Half-Duplex
Transceiver with ±65V Fault Protection,
±40V CMR, and ±40kV ESD
VCC
A
DI
GND OR VCC
RL = 110Ω
S1
OUT
D
B
CL = 50pF
DE
GENERATOR
50Ω
VCC
50%
DE
GND
tDZL
tDLZ
VCC
50%
OUT
250mV
VOL
Figure 5. Driver Enable and Disable Times (tDZL, tDLZ)
A
ATE
R
VID
RO
B
Figure 6. Receiver Propagation Delay Test Circuit
tLH ≤ 3ns, tHL ≤ 3ns
A
1V
B
-1V
tRPLH
tRPHL
RO
VOH
VCC
2
VCC
2
tRSKEW = |tRPHL - tRPLH|
www.maximintegrated.com
VOL
Maxim Integrated | 9
MAX33070E/MAX33071E/
MAX33074E
+3.3V and +5.0V, RS-485 Half-Duplex
Transceiver with ±65V Fault Protection,
±40V CMR, and ±40kV ESD
Figure 7. Receiver Propagation Delays
+1.5V
S3
RL = 1kΩ
-1.5V
VID
R
CL = 15pF
GNDB
S1
VCC
RO
S2
GND
RE
GENERATOR
50Ω
VCC
VCC
50%
RE
tRZH
VOH
GND
S1 OPEN
S2 CLOSED
S3 = +1.5V
VCC
2
GND
RO
50%
RE
GND
tRZL
VCC
2
RO
VOL
VCC
VCC
50%
RE
RE
GND
tRHZ
VOH
RO
VCC
S1 CLOSED
S2 OPEN
S3 = -1.5V
GND
S1 OPEN
S2 CLOSED
S3 = +1.5V
0.25V
50%
tRLZ
VCC
S1 CLOSED
S2 OPEN
S3 = -1.5V
RO
GND
0.25V
VOL
Figure 8. Receiver Enable and Disable Times
www.maximintegrated.com
Maxim Integrated | 10
MAX33070E/MAX33071E/
MAX33074E
+3.3V and +5.0V, RS-485 Half-Duplex
Transceiver with ±65V Fault Protection,
±40V CMR, and ±40kV ESD
Typical Operating Characteristics
(VCC = 5V, TA = +25°C, unless otherwise noted.)
80
toc01
SUPPLY CURRENT vs.
DATA RATE (VCC = 5V)
80
70
70
60
60
50
50
60Ω LOAD
120Ω LOAD
30
90
80
120Ω LOAD
30
20
20
10
NO LOAD
1
10
100
60
50
40
30
10
0
0
70
20
10
NO LOAD
0
1
1000
10
100
1000
3
3.5
DATA RATE (kbps)
4
DIFFERENTIAL OUTPUT VOLTAGE (V)
DIFFERENTIAL OUTPUT VOLTAGE (V)
VCC = 5V
VCC = 3.3V
3
2.5
2
1.5
1
0.5
0
20
40
60
3.5
VCC = 5V
2.5
2
VCC = 3.3V
1.5
1
80
100
120
5
20
35
50
65
80
tDPLH, VCC = 5V
35
50
TEMPERATURE (°C)
www.maximintegrated.com
65
80
95
35
50
65
80
95
toc09
5
4
0.7
0.6
VCC = 5V
VCC = 3.3V
0.5
0.4
0.3
VCC = 3.3V
3.5
VCC = 5V
3
2.5
2
1.5
0.2
1
0.1
0.5
0
0
20
4.5
RO OUTPUT VOLTAGE (V)
40
5
RO OUTPUT HIGH vs.
SOURCE CURRENT
toc08
1
RO OUTPUT VOLTAGE (V)
PROPAGATION DELAY (ns)
tDPLH, VCC = 3.3V
tDPLH, VCC = 3.3V
tDPLH, VCC = 5V
-40 -25 -10
0.8
80
20
tDPHL, VCC = 5V
TEMPERATURE (°C)
RO OUTPUT LOW
vs. SINK CURRENT
tDPHL, VCC = 3.3V
5
20
95
0.9
-40 -25 -10
30
TEMPERATURE (°C)
120
20
tDPHL, VCC = 3.3V
40
0
-40 -25 -10
toc07
tDPHL, VCC = 5V
toc06
10
0.5
MAX33070E DRIVER PROPAGATION
DELAY vs. TEMPERATURE
60
5.5
50
3
LOAD CURRENT (mA)
100
5
60
0
0
4.5
MAX33071E DRIVER PROPAGATION
DELAY vs. TEMPERATURE
toc05
PROPAGATION DELAY (ns)
5
DRIVER DIFFERENTIAL OUTPUT
VOLTAGE vs. TEMPERATURE
toc04
4.5
3.5
4
SUPPLY VOLTAGE (V)
DIFFERENTIAL OUTPUT
VOLTAGE vs. LOAD CURRENT
4
toc03
100
60Ω LOAD
40
40
DRIVER CURRENT vs.
SUPPLY VOLTAGE
toc02
DRIVER CURRENT (mA)
SUPPLY CURRENT vs.
DATA RATE (VCC = 3.3V)
0
0
10
20
30
40
SINK CURRENT (mA)
50
60
0
10
20
30
40
50
60
SOURCE CURRENT (mA)
Maxim Integrated | 11
MAX33070E/MAX33071E/
MAX33074E
+3.3V and +5.0V, RS-485 Half-Duplex
Transceiver with ±65V Fault Protection,
±40V CMR, and ±40kV ESD
MAX33071E RECEIVER PROPAGATION
DELAY vs. TEMPERATURE
toc10
100
160
90
60
50
40
tRPHL, VCC = 5V
30
tRPLH, VCC = 5V
20
PROPAGATION DELAY (ns)
tRPLH, VCC = 3.3V
tRPHL, VCC = 3.3V
70
120
50
65
80
95
5V/div
tRPHL, VCC = 3.3V
A, B
2V/div
RO
5V/div
40
0
35
tRPHL, VCC = 5V
60
0
20
DI
tRPLH, VCC = 5V
80
20
5
toc12
100
10
-40 -25 -10
DRIVER SWITCHING
tRPLH, VCC = 3.3V
140
80
PROPAGATION DELAY (ns)
MAX33070E RECEIVER PROPAGATION
DELAY vs. TEMPERATURE
toc11
-40 -25 -10
5
TEMPERATURE (°C)
20
35
50
65
80
95
8
VCC
7
B
TEMPERATURE (°C)
2µs/div
Pin Configuration
TOP VIEW
RO
1
2
+
MAX33070E
MAX33071E
MAX33074E
DE
3
6
A
DI
4
5
GND
8 SO
Pin Descriptions
PIN
NAME
1
RO
FUNCTION
Receiver Data Output. See the Receiver Truth Table for more information.
Receiver Output Enable. Drive
low or connect to GND to enable RO. Drive
high to
disable the receiver. RO is high impedance when
is high. Drive
high and DE low to
force the IC into low-power shutdown mode.
2
DE
Driver Output Enable. Drive DE high to enable the driver. Drive DE low or connect to GND to
disable the driver. Receiver is always enabled.
4
DI
Driver Input. See the Transmitter Truth Table for more information.
5
GND
6
A
Noninverting Driver Output/Receiver Input.
7
B
Inverting Driver Output/Receiver Input.
8
VCC
3
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Ground
Power Supply Input. Bypass VCC to GND with a 0.1μF capacitor as close as possible to the
device.
Maxim Integrated | 12
MAX33070E/MAX33071E/
MAX33074E
+3.3V and +5.0V, RS-485 Half-Duplex
Transceiver with ±65V Fault Protection,
±40V CMR, and ±40kV ESD
Detailed Description
The MAX33070E/MAX33071E/MAX33074E half-duplex transceivers are optimized for RS-485/RS-422 applications that
require ±65V protection from faults on communication bus lines. These devices contain one differential driver and one
differential receiver. These devices feature a 1/8 unit load, allowing up to 256 transceivers on a single bus. The
MAX33070E supports a data rate up to 500kbps, the MAX33071E up to 2Mbps, and the MAX33074E up to 20 Mbps.
Driver
The driver accepts a single-ended, logic-level input (DI) and transfers it to a differential RS-485 level output on the A and
B driver outputs. Set the driver enable input (DE) low to disable the driver. A and B are high impedance when the driver
is disabled.
Table 1. Transmitter Truth Table
DE
DI
A
B
X
1
0
0
1
X
1
1
1
0
0
0
X
High-Z
High-Z
1
0
X
High-Z
High-Z
Receiver
The receiver accepts a differential, RS-485 level on the A and B inputs and transfers it to a single-ended, logic-level output
(RO). Drive the receiver enable input ( ) low to enable the receiver. Drive
logic high to disable the receiver. RO is
high impedance when
is logic high.
Table 2. Receiver Truth Table
DE
(VA - VB)
RO
0
X
≥ -50mV
1
0
X
≤ -200mV
0
0
X
Open/shorted
1
1
1
X
High-Z
1
0
X
High-Z and shutdown
Low-Power Shutdown
Drive DE low and
high for at least 800ns to put the MAX33070E/MAX33071E/MAX33074E into low-power shutdown
mode. The supply current reduces to 4μA when the device is in shutdown mode. A glitch-protection feature ensures this
family of transceivers will not accidentally enter shutdown mode due to logic skews between DE and
when switching
between transmit and receive modes.
±65V Fault Protection
The driver outputs/receiver inputs of transceivers connected to an industrial RS-485 network often experience faults when
shorted to voltages that exceed the -7V to +12V input range specified in the EIA/TIA-485 standard. Under such
circumstances, ordinary RS-485 transceivers that have a typical absolute maximum voltage rating of -8V to +12.5V require
costly external protection devices which can compromise the RS-485 performance. To reduce system complexity and the
need for external protection, the driver outputs/receiver inputs of the MAX33070E/MAX33071E/MAX33074E are designed
to withstand voltage faults of up to ±65V with respect to ground without damage. Protection is guaranteed regardless
whether the transceiver is active, in shutdown, or without power. When a fault is detected on A or B, the affected driver
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Maxim Integrated | 13
MAX33070E/MAX33071E/
MAX33074E
+3.3V and +5.0V, RS-485 Half-Duplex
Transceiver with ±65V Fault Protection,
±40V CMR, and ±40kV ESD
output is switched into a high-impedance state. After 300ms (typ), the driver output is re-enabled for 30μs (typ). If the fault
condition persists, the driver output is again disabled. If the fault has been removed, the driver outputs remain on and the
transceiver operates normally. Driving a non-terminated cable may cause the voltage seen at the driver outputs (A or B)
to exceed the absolute maximum voltage rating if the DI input is switched during a ±65V fault on the A or B pins. Therefore,
a termination resistor is recommended in order to maximize the overvoltage fault protection while the DI input is being
switched. If the DI input does not change state while the fault condition is present, the
MAX33070E/MAX33071E/MAX33074E will withstand up to ±65V on the RS-485 inputs, regardless of the termination
status of the data cable.
±40V Common-Mode Range
RS-485 standards define the common-mode range as -7V to +12V for the receiver. For this family of transceivers, the
common-mode range exceeds the standard with ±40V for both the driver and receiver. This feature was specifically
designed for systems where there is a large common-mode voltage present due to either nearby electrically noisy
equipment or large ground differences due to different earth grounds or different power transformers. Two-way
communication is possible with ±40V high common-mode range where other standard RS-485 transceivers would either
fail, not transmit or receive, and/or cause data errors.
True Fail-Safe
The MAX33070E/MAX33071E/MAX33074E guarantees 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. If the differential receiver
input voltage (VA - VB) is greater than or equal to -50mV, RO is logic-high when
is logic-low.
Hot-Swap Inputs
Inserting circuit boards into a hot, or powered backplane may cause voltage transients on DE, and receiver inputs A and
B, that can lead to data errors. For example, upon initial circuit board insertion, the processor undergoes a power-up
sequence. During this period, the high impedance state of the output drivers makes them unable to drive the
MAX33070E/MAX33071E/MAX33074E DE input to a defined logic level. Meanwhile, leakage currents of up to 10μA from
the high-impedance output, or capacitively coupled noise from VCC or GND, could cause an input to drift to an incorrect
logic state. To prevent such a condition from occurring, the MAX33070E/MAX33071E/MAX33074E features hot-swap
input circuitry on DE to safeguard against unwanted driver activation during hot-swap situations. When VCC rises, an
internal pulldown circuit holds DE low for at least 10μs. After the first transition on DE, the internal pulldown/pullup circuitry
becomes transparent, resetting the hot-swap tolerable inputs.
Thermal-Shutdown Protection
The MAX33070E/MAX33071E/MAX33074E feature thermal-shutdown protection circuitry to protect the device. When the
internal silicon junction temperature exceeds +160°C (typ), the driver outputs are disabled and RO is high impedance.
Driver and receiver outputs are re-enabled when the junction temperature falls below +148°C (typ).
www.maximintegrated.com
Maxim Integrated | 14
MAX33070E/MAX33071E/
MAX33074E
+3.3V and +5.0V, RS-485 Half-Duplex
Transceiver with ±65V Fault Protection,
±40V CMR, and ±40kV ESD
Applications Information
256 Transceivers on the Bus
The MAX33070E/MAX33071E/MAX33074E transceivers have 1/8 unit load receiver, allowing for up to 256 transceivers
connected in parallel on a shared communication line. Connect any combination of these devices, and/or other RS-485
devices, for a maximum of 32 unit loads on the line.
Typical Application
The MAX33070E/MAX33071E/MAX33074E half-duplex transceivers are designed for bidirectional data communications
on multipoint bus transmission lines. The Typical Application Circuit shows a typical network application's circuit. To
minimize reflections, the bus should be terminated at the receiver inputs in its characteristic impedance, and stub lengths
off the main line should be kept as short as possible.
Power Considerations for the MAX33070E/MAX33071E/MAX33074E
At high data rates, the power dissipation of a half-duplex transceiver is determined by a number of factors, including the:
•
•
•
•
•
Data rate
Time that the driver is transmitting
Termination impedance
Power supply voltage
External common-mode voltage
Higher data rates result in higher power dissipation due to switching losses in the transceiver. Switching losses increase
even more when capacitance is applied to the A and B pins. External capacitance should be kept to a minimum to help
reduce power dissipations at high data rates. Similarly, the power dissipation in a transceiver is much higher when the
driver is transmitting, compared to when the transceiver is receiving. In half-duplex communication, the period of
transmission relative to the idle or receiving intervals (i.e., the duty cycle) should be taken into consideration when
calculating the average power dissipation. The line termination resistance/impedance determines the driver's load current
during transmission and the differential output voltage (VOD) on the driver is determined by the supply voltage. A higher
supply voltage results in a larger differential output voltage at the driver driving the line, which in turn results in a higher
current draw from the supply (ICC). The power dissipation in the chip is calculated as the product of supply current times
supply voltage, subtracting the power dissipated in the external termination resistor. If there is a common-mode voltage
(higher than VCC) present (Figure 1b), the transceiver will pull this voltage down to operating levels by sinking current into
the A pin (or B pin, whichever is lower). This is factored into the following equation:
PDIS = (VCC x ICC) - (VOD2/RL) + (VAB x IAB)
where IAB = ((VCM – VAB)/375) + ((VCC-VAB)/RL).
Use the Typical Operating Characteristics to determine the supply current at a given supply voltage and data rate. For
example, assuming a data rate of 500kbps with a 5V supply on a fully loaded bus with +40V common mode (Figure 1b),
and assuming VAB = 1.5V (the lower of A, B), we can calculate that the power dissipation (at room temperature) is:
PDIS = (5V x 65mA) - (3.4V2/60Ω) + (1.5V x 160mA) = 564mW
Ensure that power dissipation of the transceiver is kept below the value listed in the Absolute Maximum Ratings to protect
the device from entering thermal shutdown or from damage.
PCB Layout Considerations
PCB layout can affect the performance of the transceiver in conditions with high common-mode voltage at a high ambient
temperature. In order to maximize thermal dissipation, it is recommended to:
1.
Use large copper pads for all the pins.
2.
Connect the GND pad to a large copper plane on the same layer or through vias to the bottom layer.
www.maximintegrated.com
Maxim Integrated | 15
MAX33070E/MAX33071E/
MAX33074E
+3.3V and +5.0V, RS-485 Half-Duplex
Transceiver with ±65V Fault Protection,
±40V CMR, and ±40kV ESD
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 (A and B data lines) of the
MAX33070E/MAX33071E/MAX33074E have extra protection against static electricity. The ESD structures withstand high
ESD in normal operation and when powered down. After an ESD event, the devices keep working without latch-up or
damage.
ESD protection can be tested in various ways. The transmitter outputs and receiver inputs (A and B data lines) of the
devices are characterized for protection to the cable-side ground (GNDB) to the following limits:
•
±40kV HBM per JEDEC JS-001-2017
•
±15kV using the Air-Gap Discharge method specified in the IEC 61000-4-2
•
±10kV using the Contact Discharge method specified in the IEC 61000-4-2
The other non-data pins are also ESD protected, but at a lower level per the Electrical Characteristics table.
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 9 shows the HBM test model and Figure 10 shows the current waveform it generates when discharged in a lowimpedance 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
1MΩ
RD
1500Ω
CHARGE-CURRENTLIMIT RESISTOR
HIGHVOLTAGE
DC
SOURCE
DISCHARGE
RESISTANCE
DEVICE
UNDER
TEST
STORAGE
CAPACITOR
CS
100pF
Figure 9. Human Body ESD Test Model
IP 100%
90%
Ir
PEAK-TO-PEAK
RINGING
(NOT DRAWN TO SCALE)
AMPS
36.8%
10%
0
0
tRL
TIME
tDL
CURRENT WAVEFORM
Figure 10. Human Body Current Waveform
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Maxim Integrated | 16
MAX33070E/MAX33071E/
MAX33074E
+3.3V and +5.0V, RS-485 Half-Duplex
Transceiver with ±65V Fault Protection,
±40V CMR, and ±40kV ESD
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 MAX33070E/MAX33071E/MAX33074E help in designing equipment to meet IEC 610004-2 without the need for additional ESD protection components. The major difference between tests done using the HBM
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 withstand voltage measured to IEC 61000-4-2 is generally lower than that measured using the
HBM. Figure 11 shows the IEC 61000-4-2 model and Figure 12 shows the current waveform for IEC 61000-4-2 ESD
Contact Discharge, and Air-Gap tests.
RC
50MΩ TO 100MΩ
CHARGE-CURRENTLIMIT RESISTOR
HIGHVOLTAGE
DC
SOURCE
CS
150pF
RD
330Ω
DISCHARGE
RESISTANCE
STORAGE
CAPACITOR
DEVICE
UNDER
TEST
Figure 11. IEC 61000-4-2 ESD Test Model
CURRENT
100%
90%
10%
tR = 0.7 - 1ns
TIME
30ns
60ns
Figure 12. IEC 61000-4-2 ESD Generator Current Waveform
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Maxim Integrated | 17
MAX33070E/MAX33071E/
MAX33074E
+3.3V and +5.0V, RS-485 Half-Duplex
Transceiver with ±65V Fault Protection,
±40V CMR, and ±40kV ESD
Typical Application Circuits
Typical RS-485 Network
B
DI
B
D
DE
RE
RO
D
120Ω
120Ω
A
R
B
MAX33070E
MAX33071E
MAX33074E
DE
RE
A
R
A
D
DI
DE RE
B
DI
RO
A
R
D
RO
DI
R
DE RE
RO
Ordering Information
PART NUMBER
TEMPERATURE RANGE
PIN-PACKAGE
MAXIMUM DATA RATE
MAX33070EASA+
-40°C to +125°C
8 SO
500kbps
MAX33070EASA+T
-40°C to +125°C
8 SO
500kbps
MAX33071EASA+
-40°C to +125°C
8 SO
2Mbps
MAX33071EASA+T
-40°C to +125°C
8 SO
2Mbps
MAX33074EASA+*
-40°C to +125°C
8 SO-EP
20Mbps
MAX33074EASA+T*
-40°C to +125°C
8 SO-EP
20Mbps
+ = Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
*Future product—contact factory for availability.
www.maximintegrated.com
Maxim Integrated | 18
MAX33070E/MAX33071E/
MAX33074E
+3.3V and +5.0V, RS-485 Half-Duplex
Transceiver with ±65V Fault Protection,
±40V CMR, and ±40kV ESD
Revision History
REVISION
NUMBER
0
REVISION
DATE
1/21
DESCRIPTION
Initial release
PAGES
CHANGED
—
For pricing, delivery, and ordering information, please visit Maxim Integrated’s online storefront at https://www.maximintegrated.com/en/storefront/storefront.html.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
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