MAX14938-39 Datasheet by Maxim Integrated

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General Description
The MAX14938/MAX14939 isolated RS-485/PROFIBUS-DP
transceivers provide 2750VRMS (60s) of galvanic isolation
between the cable side (RS-485 driver/receiver side) and
the UART side 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
20Mbps.
An integrated LDO provides a simple and space-efficient
architecture for providing power to the cable side of the
IC.
Each device includes one half-duplex driver/receiver
channel. The receiver is 1/4-unit load, allowing up to 128
transceivers on a common bus.
Integrated true fail-safe circuitry ensures a logic-high on
the receiver output when inputs are shorted or open.
Undervoltage lockout disables the driver when cable-side
or UART-side power supplies are below functional levels.
The driver outputs/receiver inputs are protected from
±35kV electrostatic discharge (ESD) to GNDB on the
cable side, as specified by the Human Body Model (HBM).
The MAX14938/MAX14939 are available in a wide-body
16-pin SOIC package and operate over the -40°C to
+105°C temperature range.
Benefits and Features
High-Performance Transceiver Enables Flexible Designs
Integrated LDO for Cable-Side Power
Compliant with RS-485 EIA/TIa-485 Standard
20Mbps Maximum Data Rate
Allows Up to 128 Devices on the Bus
Integrated Protections Ensures Robust Communication
±35kV ESD (HBM) on Driver Outputs/Receiver Inputs
2.75kVRMS Withstand Isolation Voltage for 60s (VISO)
630VPEAK Maximum Repetitive Peak-Isolation
Voltage (VIORM)
445VRMS Maximum Working-Isolation Voltage
(VIOWM)
> 30 Years Lifetime at Rated Working Voltage
Withstands ±10kV Surge per IEC 61000-4-5
Thermal Shutdown
Safety Regulatory Approvals
UL According to UL1577
cUL According to CSA Bulletin 5A
Applications
Industrial Automation Equipment
Programmable Logic Controllers
HVAC
Power Meters
Ordering Information appears at end of data sheet.
19-8115; Rev 1; 1/17
Functional Diagram
LDO
RS-485 TRANSCEIVER
VDDA
RXD
RE
TXD
DE
A
B
VDDB
VLDO
GNDA GNDB
(DEM)
MAX14938
MAX14939
(PV)
SBA
+
() MAX14938 only
* MAX14939 only
MAX14938/MAX14939 2.75kVRMS Isolated 20Mbps Half-Duplex PROFIBUS/
RS-485 Transceivers with ±35kV ESD Protection
EVALUATION KIT AVAILABLE
VDDA to GNDA ......................................................-0.3V to +6V
VDDB to GNDB .......................................................-0.3V to +6V
VLDO to GNDB .....................................................-0.3V to +16V
TXD, DE, RE, PV to GNDA .................................... -0.3V to +6V
SBA, RXD to GNDA ............................. -0.3V to (VDDA + 0.3V)
DEM to GNDB ...................................... -0.3V to (VDDB + 0.3V)
A, B to GNDB ...........................................................-8V to +13V
Short Circuit Duration (RXD, SBA to GNDA,
A, B, DEM ,VDDB to GNDB)..................................Continuous
Continuous Power Dissipation (TA = +70°C)
16-pin W SOIC (derate 14.1mW/°C
above +70°C) .........................................................1126.8mW
Operating Temperature Range ......................... -40°C to +105°C
Junction Temperature ...................................................... +150°C
Storage Temperature Range ............................ -65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°C
Junction-to-Ambient Thermal Resistance (θJA) ..............71°C/W Junction-to-Case Thermal Resistance (θJC) ...................23°C/W
(Note 1)
DC Electrical Characteristics
(VDDA – VGNDA = 1.71V to 5.5V, VDDB – VGNDB = 4.5V to 5.5V, 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 2, 3)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
POWER
Supply Voltage VDDA 1.71 5.5 V
VDDB 4.5 5.5
Supply Current
IDDA
VDDA = 5V, DE = high, RE = TXD = low,
RXD unconnected, no load 4 6.6
mA
IDDB
DE = high, RE = TXD = low, RXD
unconnected, no bus load, VDDB = 5V 7.6 12.5
Undervoltage-Lockout
Threshold
VUVLOA VDDA rising 1.50 1.58 1.65 V
VUVLOB VDDB rising 2.55 2.7 2.85
Undervoltage-Lockout
Threshold Hysteresis
VUVHYSTA 50 mV
VUVHYSTB 200
LDO
LDO Supply Voltage VLDO Relative to GNDB, LDO is on (Note 4) 4.68 14 V
LDO Supply Current ILDO DE = high, TXD = low, no bus load,
VLDO = 5V 7.7 12.9 mA
LDO Output Voltage VDDB 4.5 5 5.5 V
LDO Current Limit 300 mA
Load Regulation VLDO = 5.68V, ILOAD = 20mA to
40mA 0.19 1.7 mV/mA
Line Regulation VLDO = 5.68V to 14V, ILOAD = 20mA 0.12 4.5 mV/V
MAX14938/MAX14939 2.75kVRMS Isolated 20Mbps Half-Duplex PROFIBUS/
RS-485 Transceivers with ±35kV ESD Protection
www.maximintegrated.com Maxim Integrated
2
Note 1: 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.
Absolute Maximum Ratings
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 Thermal Characteristics
DC Electrical Characteristics (continued)
(VDDA – VGNDA = 1.71V to 5.5V, VDDB – VGNDB = 4.5V to 5.5V, 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 2, 3)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Dropout Voltage VLDO = 4.68V, IDDB = 120mA 100 180 mV
Load Capacitance Nominal value (Note 8) 1 10 µF
LOGIC INTERFACE (TXD, RXD, DE, RE, SBA, PV, DEM)
Input High Voltage VIH
RE, TXD, DE,
PV to GNDA
2.25V < VDDA < 5.5V 0.7 x
VDDA V
1.71V < VDDA < 1.89V 0.78 x
VDDA
Input Low Voltage VIL
RE, TXD, DE,
PV to GNDA
2.25V < VDDA < 5.5V 0.8 V
1.71V < VDDA < 1.89V 0.6
Input Hysteresis VHYS RE, TXD, DE, PV to GNDA 220 mV
Input Capacitance CIN RE, TXD, DE, PV, fSW = 1MHz 2 pF
Input Pull-Up Current IPU TXD, PV -10 -4.5 -1.5 µA
Input Pull-Down Current IPD DE, RE 1.5 4.5 10 µA
SBA Pull-Up Resistance RSBA MAX14939 only 3 5 8 kΩ
Output Voltage High VOH
RXD to GNDA, IOUT = -4mA VDDA
-0.4 V
MAX14938 only, DEM to GNDB,
IOUT = -4mA
VDDB
-0.4
Output Voltage Low VOL
RXD to GNDA, IOUT = 4mA 0.40
V
MAX14938 only, DEM to GNDB,
IOUT = 4mA 0.40
MAX14939 only, SBA to GNDA,
IOUT = 4mA 0.45
Short-Circuit Output Pullup
Current ISH_PU
0V ≤ VRXD ≤ VDDA, RE = low -42
mA
MAX14938 only, 0V ≤ VDEM ≤ VDDB,
DE = high, PV = high -42
Short-Circuit Output Pulldown
Current ISH_PD
0V ≤ VRXD ≤ VDDA, RE = low +40
mA
MAX14938 only, 0V ≤ VDEM ≤ VDDB,
DE = low, PV = high +40
MAX14939 only, 0V ≤ VSBA ≤ VDDA,
side B is powered and working +60
Three-State Output Current IOZ 0V ≤ VRXD ≤ VDDA, RE = high -1 +1 µA
MAX14938/MAX14939 2.75kVRMS Isolated 20Mbps Half-Duplex PROFIBUS/
RS-485 Transceivers with ±35kV ESD Protection
www.maximintegrated.com Maxim Integrated
3
DC Electrical Characteristics (continued)
(VDDA – VGNDA = 1.71V to 5.5V, VDDB – VGNDB = 4.5V to 5.5V, 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 2, 3)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
DRIVER
Differential Driver Output |VOD|
RL = 54Ω, TXD = high or low,
Figure 1a 2.1
V
RL = 100Ω, TXD = high or low,
Figure 1a 2.9
-7V ≤ VCM ≤ +12V, Figure 1b 1.5 5
Differential Driver
Peak-to-Peak Output VODPP Figure 2 (Note 5) 4.0 6.8 V
Change in Magnitude of
Differential Driver Output Voltage ΔVOD RL = 54Ω (Note 6) -0.2 +0.2 V
Driver Common Mode Output
Voltage VOC RL = 54Ω, Figure 1a 1.8 3 V
Change in Magnitude of
Common-Mode Voltage ΔVOC RL = 54Ω, Figure 1a (Note 6) -0.2 +0.2 V
Driver Short-Circuit Output
Current IOSD
GNDB ≤ VOUT ≤ +12V, output low
(Note 7) +250
mA
-7V ≤ VOUT ≤ VDDB, output high
(Note 7) -250
Driver Short-Circuit Foldback
Output Current IOSDF
(VDDB – 1V) ≤ VOUT ≤ +12V,
output low (Note 7, 8) +15
mA
-7V ≤ VOUT ≤ +1V, output high
(Note 7, 8) -15
RECEIVER
Input Current (A and B) IA, IB
DE = low,
VDDB = GNDB
or 5.5V
VIN = +12V +250
µA
VIN = -7V -200
Receiver Differential Threshold
Voltage VTH -7V ≤ VCM ≤ +12V -200 -125 -50 mV
Receiver Input Hysteresis ΔVTH VCM = 0V 15 mV
Receiver Input Resistance RIN -7V ≤ VCM ≤ +12V, DE = low 48
Differential Input Capacitance CA,B Measured between A and B, DE = RE
= low at 6MHz 8 pF
MAX14938/MAX14939 2.75kVRMS Isolated 20Mbps Half-Duplex PROFIBUS/
RS-485 Transceivers with ±35kV ESD Protection
www.maximintegrated.com Maxim Integrated
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DC Electrical Characteristics (continued)
(VDDA – VGNDA = 1.71V to 5.5V, VDDB – VGNDB = 4.5V to 5.5V, 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 2, 3)
Switching Electrical Characteristics
(VDDA – VGNDA = 1.71V to 5.5V, VDDB – VGNDB = 4.5V to 5.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are
at VDDA – VGNDA = 3.3V, VDDB – VGNDB = 5V, VGNDA = VGNDB, and TA = +25°C.) (Note 8)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
PROTECTION
Thermal-Shutdown Threshold TSHDN Temperature Rising +160 °C
Thermal-Shutdown Hysteresis THYST 15 °C
ESD Protection
(A and B Pins to GNDB)
Human Body Model ±35
kV
IEC 61000-4-2 Air Gap Discharge ±12
IEC 61000-4-2 Contact Discharge ±10
ESD Protection (All Other Pins) Human Body Model ±4 kV
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
DYNAMIC
Common Mode Transient
Immunity CMTI (Note 9) 35 kV/μs
Glitch Rejection TXD, DE, RXD 10 17 29 ns
DRIVER
Driver Propagation Delay tDPLH, tDPHL RL = 54Ω, CL = 50pF, Figure 3 and
Figure 4 68 ns
Differential Driver Output Skew
|tDPLH – tDPHL|tDSKEW RL = 54Ω, CL = 50pF, Figure 3 and
Figure 4 6 ns
Driver Differential Output Rise
or Fall Time tLH, tHL RL = 54Ω, CL = 50pF, Figure 3 and
Figure 4 15 ns
Maximum Data Rate DRMAX 20 Mbps
Driver Enable to Output High tDZH RL = 500Ω, CL = 50pF, Figure 5 88 ns
MAX14938/MAX14939 2.75kVRMS Isolated 20Mbps Half-Duplex PROFIBUS/
RS-485 Transceivers with ±35kV ESD Protection
www.maximintegrated.com Maxim Integrated
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Switching Electrical Characteristics (continued)
(VDDA – VGNDA = 1.71V to 5.5V, VDDB – VGNDB = 4.5V to 5.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are
at VDDA – VGNDA = 3.3V, VDDB – VGNDB = 5V, VGNDA = VGNDB, and TA = +25°C.) (Note 8)
Note 2: All devices are 100% production tested at TA = +25°C. Specifications over temperature are guaranteed by design.
Note 3: 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 4: VLDO max indicates voltage capability of the circuit. Power dissipation requirements may limit VLDO max to a lower value.
Note 5: VODPP is the difference in VOD when TXD is high and when TXD is low.
Note 6: ΔVOD and ΔVOC are the changes in VOD and VOC, respectively, when the TXD input changes state.
Note 7: The short circuit output current applies to the peak current just prior to foldback current limiting.
Note 8: Not production tested. Guaranteed by design.
Note 9: 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. ΔVCM = 1kV.
Note 10: Capacitive load includes test probe and fixture capacitance.
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Driver Enable to Output Low tDZL RL = 500Ω, CL = 50pF, Figure 6 88 ns
Driver Disable Time from Low tDLZ RL = 500Ω, CL = 50pF, Figure 6 80 ns
Driver Disable Time from High tDHZ RL = 500Ω, CL = 50pF, Figure 5 80 ns
RECEIVER
Receiver Propagation Delay tRPLH, tRPHL CL = 15pF, Figure 7 and 8 (Note 10) 68 ns
Receiver Output Skew
|tRPLH - tRPHL|tRSKEW CL = 15pF, Figure 7 and 8
(Note 10) 6 ns
Maximum Data Rate DRMAX 20 Mbps
Receiver Enable to Output
High tRZH RL = 1kΩ, CL = 15pF, S2 closed,
Figure 9 20 ns
Receiver Enable to Output Low tRZL RL = 1kΩ, CL = 15pF, S1 closed,
Figure 9 30 ns
Receiver Disable Time From
Low tRLZ RL = 1kΩ, CL = 15pF, S1 closed,
Figure 9 20 ns
Receiver Disable Time From
High tRHZ RL = 1kΩ, CL = 15pF, S2 closed,
Figure 9 20 ns
MAX14938/MAX14939 2.75kVRMS Isolated 20Mbps Half-Duplex PROFIBUS/
RS-485 Transceivers with ±35kV ESD Protection
www.maximintegrated.com Maxim Integrated
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Safety Regulatory Approvals
Insulation Characteristics
Note 11: VIORM, VIOWM, and VISO are defined by the IEC 60747-5-5 standard.
Note 12: Product is qualified at VISO for 60 seconds. 100% production tested at 120% of VISO for 1 second.
UL
The MAX14938/MAX14939 is certified under UL1577. For more details, see File E351759.
Rate up to 2750VRMS isolation voltage for basic insulation.
cUL
The MAX14938/MAX14939 is certified under UL1577. For more details, see File E351759.
Rate up to 2750VRMS isolation voltage for basic insulation.
PARAMETER SYMBOL CONDITIONS VALUE UNITS
Partial Discharge Test Voltage VPR
Method B1 = VIORM x 1.875 (t = 1s, partial
discharge < 5pC) 1182 VP
Maximum Repetitive Peak Withstand
Voltage VIORM (Note 11) 630 VP
Maximum Working Isolation Voltage VIOWM (Note 11) 445 VRMS
Maximum Transient Isolation Voltage VIOTM t = 1s 4600 VP
Maximum Withstand Isolation Voltage VISO t = 60s, f = 60Hz (Note 11, 12) 2750 VRMS
Maximum surge Isolation Voltage VIOSM IEC 61000-4-5, 1.2/50μs 10 kV
Insulation Resistance RSTA = +150°C, VIO = 500V >109Ω
Barrier Capacitance Input to Output CIO 2 pF
Creepage Distance CPG Wide SO 8mm
Clearance Distance CLR Wide SO 8 mm
Internal Clearance Distance through insulation 0.015 mm
Comparitive Tracking Resistance
Index CTI Material Group II (IEC 60112) 575
Climatic Category 40/125/21
Pollution Degree (DIN VDE 0110,
Table 1) 2
MAX14938/MAX14939 2.75kVRMS Isolated 20Mbps Half-Duplex PROFIBUS/
RS-485 Transceivers with ±35kV ESD Protection
www.maximintegrated.com Maxim Integrated
7
Figure 1. Driver DC Test Load Figure 2. VODPP Swing Under PROFIBUS Equivalent Load Test
R
L
2
R
L
2
V
OC
V
OD
Y
Z
(a)
375Ω
V
CM
Y
Z
(b)
375Ω
+
-
60Ω
V
OD
RLCL
VOD
TXD
GNDA
A
B
50% 50%
GNDA
TXD
B
A
20%
80%
20%
80%
0
VO
-VO
VDIFF
tDSKEW = |tDPLH - tDPHL|
VDIFF = VA - VB
VDDA
f = 1MHz, tLH P 3ns, tHL P 3ns
1/2 VO
tDPLH
tLH tHL
tDPHL
VO
1/2 VO
GNDB
TXD
A
B
GNDA
VDDB
VDDA
195I
110IVOD
195I
Figure 3. Driver Timing Test Circuit
Figure 4. Driver Propagation Delays
MAX14938/MAX14939 2.75kVRMS Isolated 20Mbps Half-Duplex PROFIBUS/
RS-485 Transceivers with ±35kV ESD Protection
www.maximintegrated.com Maxim Integrated
8
Figure 5. Driver Enable and Disable Times (tDHZ, tDZH)
Figure 6. Driver Enable and Disable Times (tDZL, tDLZ)
GNDA
GNDB
250mV
50%
tDZH
tDHZ
DE
VDDA
VOH
50%
OUT
RL = 500I
50I
OUT
S1
A
B
D
TXD
GNDA OR VDDA
GNDA
GNDB
GENERATOR
DE
CL
50pF
RL = 500I
CL = 50pF
50I
GNDB
GNDA
OUT
GNDA
250mV
50%
tDZL
tDLZ
DE
S1
A
B
D
TXD
GNDA OR VDDA
VDDB
VDDA
50%
OUT
VDDB
VOL
GENERATOR
DE
Figure 7. Receiver Propagation Delay Test Circuit
VID
B
A
RECEIVER
OUTPUT
ATE R
MAX14938/MAX14939 2.75kVRMS Isolated 20Mbps Half-Duplex PROFIBUS/
RS-485 Transceivers with ±35kV ESD Protection
www.maximintegrated.com Maxim Integrated
9
Figure 8. Receiver Propagation Delays
A
B
VOH
VOL
RXD
tRPHL
tRSKEW = |tRPHL - tRPLH|
f = 1MHz, tLH P 3ns, tHL P 3ns
tRPLH
-1V
1V
2
VDDA
2
VDDA
Figure 9. Receiver Enable and Disable Times
GENERATOR 50I
RL
1kI
CL
15pF
R
-1.5V
+1.5V
RXD
S1 VDDA
GNDA
GNDB
GNDA
S2
S3
VID
RE
RE
RXD
RE
RXD
RE RE
RXD RXD
GNDA
tRHZ tRLZ
0.25V
0.25V
50% 50%
GNDA GNDA
2
S1 OPEN
S2 CLOSED
S3 = +1.5V
S1 OPEN
S2 CLOSED
S3 = +1.5V
S1 CLOSED
S2 OPEN
S3 = -1.5V
S1 CLOSED
S2 OPEN
S3 = -1.5V
VOH
GNDA
GNDA
VOH
VDDA
VDDA
VDDA
50%50%
VDDA
tRZL
VOL
GNDA
VDDA
VDDA
VDDA
VOL
tRZH
2
VDDA
MAX14938/MAX14939 2.75kVRMS Isolated 20Mbps Half-Duplex PROFIBUS/
RS-485 Transceivers with ±35kV ESD Protection
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(VDDA – VGNDA = 3.3V, VDDB – VGNDB = 5V, VGNDA = VGNDB, and TA = +25°C, unless otherwise noted.)
0
5
10
15
20
25
30
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
SOURCE CURRENT (mA)
OUTPUT HIGH VOLTAGE (V)
RECEIVER OUTPUT CURRENT
vs OUTPUT HIGH VOLTAGE toc04
0
1
2
3
4
5
6
7
8
-45 -30 -15 015 30 45 60 75 90 105
IDDA (mA)
TEMPERATURE (°C)
VDDA SUPPLY CURRENT
vs. TEMPERATURE toc01
NO LOAD
NO SWITCHING
-140
-120
-100
-80
-60
-40
-20
0
20
-7 -6 -5 -4 -3 -2 -1 012345
OUTPUT CURRENT (mA)
OUTPUT HIGH VOLTAGE (V)
DRIVER OUTPUT CURRENT
vs OUTPUT HIGH VOLTAGE toc07
0
2
4
6
8
10
12
14
-45 -30 -15 015 30 45 60 75 90 105
IDDB (mA)
TEMPERATURE (°C)
VDDB SUPPLY CURRENT
vs. TEMPERATURE toc02
NO LOAD
NO SWITCHING
0
5
10
15
20
25
30
-45 -30 -15 015 30 45 60 75 90 105
PROPAGATION DELAY (ns)
TEMPERATURE (°C)
TRANSMITTER PROPAGATION
DELAY vs. TEMPERATURE toc08
RL= 54
CL= 50pF
tPDHL
tPDLH
0
5
10
15
20
25
30
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
SINK CURRENT (mA)
OUTPUT LOW VOLTAGE (V)
RECEIVER OUTPUT CURRENT
vs OUTPUT LOW VOLTAGE toc03
0
5
10
15
20
25
30
35
40
45
50
-45 -30 -15 015 30 45 60 75 90 105
PROPAGATION DELAY (ns)
TEMPERATURE (°C)
RECEIVER PROPAGATION
DELAY vs. TEMPERATURE toc09
tRPHL
tRPLH
CL= 15pF
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
-45 -30 -15 015 30 45 60 75 90 105
VOD (V)
TEMPERATURE (°C)
DIFFERENTIAL OUTPUT VOLTAGE
vs. TEMPERATURE toc05
No load
120LOAD 54LOAD
0
20
40
60
80
100
120
140
012345678910 11 12
OUTPUT CURRENT (mA)
OUTPUT LOW VOLTAGE (V)
DRIVER OUTPUT CURRENT
vs OUTPUT LOW VOLTAGE toc6
Maxim Integrated
11
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MAX14938/MAX14939 2.75kVRMS Isolated 20Mbps Half-Duplex PROFIBUS/
RS-485 Transceivers with ±35kV ESD Protection
Typical Operating Characteristics
DRIVE ENAELHDISABLE new n. TEMPEWURE RECENE? munnmau new wmaum. Dm m1: DRIVE PROPAGATM nan vw SUPPLV cuRRENT u. mm m:
(VDDA – VGNDA = 3.3V, VDDB – VGNDB = 5V, VGNDA = VGNDB, and TA = +25°C, unless otherwise noted.)
RECEIVER
PROPAGATION DELAY
RXD
2V/div
0V
B
1V/div
A
1V/div
toc12
10ns/div
CL= 15pF
0
10
20
30
40
50
60
70
80
-45 -30 -15 015 30 45 60 75 90 105
ENABLE/DISABLE DELAY (ns)
TEMPERATURE (°C)
DRIVER ENABLE/DISABLE
DELAY vs. TEMPERATURE toc10
tDZH
tDZL
tDHZ
tDLZ
0
10
20
30
40
50
60
70
80
0 5 10 15 20
IDDB (mA)
DATA RATE (Mbps)
VDDB SUPPLY
CURRENT vs. DATA RATE toc14
NO LOAD
54LOAD
120LOAD
DRIVER
PROPAGATION DELAY
TXD
2V/div
0V
A
1V/div
B
1V/div
toc11
10ns/div
RL= 54
CL= 50pF
0
1
2
3
4
5
6
7
8
0 5 10 15 20
IDDA (mA)
DATA RATE (Mbps)
VDDA SUPPLY CURRENT
vs. DATA RATE toc13
Maxim Integrated
12
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MAX14938/MAX14939 2.75kVRMS Isolated 20Mbps Half-Duplex PROFIBUS/
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Typical Operating Characteristics (continued)
PIN NAME REFERENCE FUNCTION
MAX14938 MAX14939
1 1 VDDA GNDA UART/Logic-Side Power Input. Bypass VDDA to GNDA with both 0.1µF and
1µF capacitors as close to the device as possible.
2, 8 2, 8 GNDA - UART/Logic-Side Ground. GNDA is the ground reference for digital signals.
3 3 RXD GNDA
Receiver Data Output. Drive RE low to enable RXD. With RE low, RXD is high
when (VA – VB) > -50mV and is low when (VA – VB) < -200mV. RXD is high
when VDDB is less than VUVLOB. RXD is high impedance when RE is high.
4 4 RE GNDA
Receiver Output Enable. Driver RE low or connect to GNDA to enable RXD.
Drive RE high to disable RXD. RXD is high-impedance when RE is high. RE
has an internal 4.5µA pull-down to GNDA.
5 5 DE GNDA
Driver Output Enable. Drive DE high to enable bus driver outputs A and B. Drive
DE low or connect to GNDA to disable A and B. A and B are high impedance
when DE is low. DE has an internal 4.5µA pull-down to GNDA.
6 6 TXD GNDA
Driver Input. With DE high, a low on TXD forces the noninverting output (A) low
and the inverting output (B) high. Similarly, a high on TXD forces the noninvert-
ing output high and the inverting output low. TXD has an internal 4.5µA pull-up
to VDDA.
N.C.
BRE
1
2
16
15
V
DDB
GNDBGNDA
RXD
V
DDA
WIDE SOIC
3
4
14
13
V
LDO
N.C.SBA
5 12 ADE
TXD 6
7
11
10
GNDBGNDA 8 9
MAX14939
+
N.C.
BRE
1
2
16
15
V
DDB
GNDBGNDA
RXD
V
DDA
TOP VIEW
3
4
14
13
V
LDO
DEMPV
5 12 ADE
TXD 6
7
11
10
GNDBGNDA 8 9
MAX14938
+
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13
Pin Configuration
Pin Description
PIN NAME REFERENCE FUNCTION
MAX14938 MAX14939
7 - PV GNDA
Power Valid Input. Hold PV low to disable the driver while the supplies stabilize.
Pull PV high when power is stable to enable the driver. PV has an internal 4.5µA
pull-up to VDDA.
7 SBA GNDA Side B Active Indicator Output. SBA asserts low when side B is powered and
working. SBA has an internal 5kΩ pull-up resistor to VDDA.
9, 15 9, 15 GNDB Cable-Side Ground. GNDB is the ground reference for the internal LDO, the
DEM output, and the Profibus/RS-485 bus signals.
10 - DEM GNDB Driver Enable Monitor Output. DEM is high when the transmitter is enabled.
See the Function Tables for more information.
14 10, 14 N.C. No Connection. Not internally connected.
11 11 VLDO GNDB
LDO Power Input. Connect a minimum voltage of 4.68V to VLDO to power the
cable-side of the transceiver. Bypass VLDO to GNDB with both 0.1µF and 1µF
capacitors as close to the device as possible. To disable the internal LDO, leave
VLDO unconnected or connect to GNDB.
12 12 A GNDB Noninverting Receiver Input and Noninverting Driver Output
13 13 B GNDB Inverting Receiver Input and Inverting Driver Output
16 16 VDDB GNDB
Cable-Side Power Input/Isolated LDO Power Output. Bypass VDDB to GNDB
with both 0.1µF and 1μF capacitor as close to the device as possible. VDDB
is the output of the internal LDO when power is applied to VLDO. When the
internal LDO is not used (VLDO is unconnected or connected to GNDB), VDDB
is the positive supply input for the cable-side of the IC.
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Pin Description (continued)
*Note: Drive DE low to disable the transmitter outputs. Drive DE high to enable the transmitter outputs. DE has an internal pull-down
to GNDA.
** MAX14938 only, X = Don’t care
*Note: Drive RE high to disable the receiver output. Drive RE low to enable to receiver output. RE has an internal pulldown to GNDA.
X = Don’t care
Function Tables
TRANSMITTING
INPUTS OUTPUTS
VDDA VDDB DE TXD PV** ABDEM**
≥ VUVLOA ≥ VUVLOB 111101
≥ VUVLOA ≥ VUVLOB 101011
≥ VUVLOA ≥ VUVLOB 0 X X High-Z High-Z 0
< VUVLOA ≥ VUVLOB X X X High-Z High-Z 0
≥ VUVLOA < VUVLOB X X X High-Z High-Z 0
< VUVLOA < VUVLOB X X X High-Z High-Z 0
RECEIVING
INPUTS OUTPUTS
VDDA VDDB RE (VA- VB) RXD
≥ VUVLOA ≥ VUVLOB 0 > -50mV 1
≥ VUVLOA ≥ VUVLOB 0 < -200mV 0
≥ VUVLOA ≥ VUVLOB 0 Open/Short 1
≥ VUVLOA ≥ VUVLOB 1 X High-Z
< VUVLOA ≥ VUVLOB X X High-Z
≥ VUVLOA < VUVLOB 0 X 1
< VUVLOA < VUVLOB X X High-Z
SBA
VDDA VDDB SBA
< VUVLOA < VUVLOB High
< VUVLOA ≥ VUVLOB High
≥ VUVLOA < VUVLOB High
≥ VUVLOA ≥ VUVLOB Low
MAX14938/MAX14939 2.75kVRMS Isolated 20Mbps Half-Duplex PROFIBUS/
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15
Detailed Description
The MAX14938/MAX14939 isolated PROFIBUS-DP/
RS-485 transceivers provide 2750VRMS (60s) of galvan-
ic isolation between the PROFIBUS-DP/RS-485 cable-
side of the transceiver and the UART side. These devices
allow fast (20Mbps) 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 Profibus/RS-485 cable side of the transceiver.
Integrated LDO
The MAX14938/MAX14939 include an internal low-drop-
out regulator with a set 5V (typ) output that is used to
power the cable-side of the IC. The output of the LDO
is VDDB. In addition to powering the transceiver, VDDB
can source up to 10mA, allowing external termination
resistors to be powered without the need for an external
regulator. The LDO has a 300mA (typ) current limit. If the
LDO is unused, connect VLDO to GNDB and apply +5V
directly to VDDB.
True Fail-Safe
The MAX14938/MAX14939 guarantee a logic-high on
the receiver output when the receiver inputs are shorted
or open, or when connected to a terminated transmis-
sion line with all drivers disabled. The receiver threshold
is fixed between -50mV and -200mV. If the differential
receiver input voltage (VA – VB) is greater than or equal
to -50mV, RXD is logic-high. In the case of a terminated
bus with all transmitters disabled, the receiver’s differen-
tial input voltage is pulled to zero by the termination resis-
tors. Due to the receiver thresholds of the MAX14938/
MAX14939, this results in a logic-high at RXD.
Driver Output Protection
Two mechanisms prevent excessive output current and
power dissipation caused by faults or bus contention. The
first, a foldback mode current limit on the output stage, provides
immediate protection against short circuits over the entire
common-mode voltage range. The second, a thermal-
shutdown circuit, forces the driver outputs into a
high-impedance state if the die temperature exceeds
+160°C (typ).
Thermal Shutdown
The MAX14938/MAX14939 are protected from
overtemperature damage by integrated thermal
shutdown circuitry. When the junction temperature
(TJ) exceeds +160°C (typ), the driver outputs go high-
impedance. The device resumes normal operation when
TJ falls below +145°C (typ).
Applications Information
128 Transceivers on the Bus
The standard RS-485 receiver input impedance is one unit
load. A standard driver can drive up to 32 unit-loads. The
MAX14938/MAX14939 transceivers have a ¼-unit load
receiver, which allows up to 128 transceivers, connected
in parallel, on one communication line. Connect any com-
bination of these devices, and/or other RS-485 devices,
for a maximum of 32 unit-loads to the line.
Typical Application
The MAX14938/MAX14939 transceivers are designed
for bidirectional data communications on multipoint bus
transmission lines. Figure 10 and Figure 11 show typical
network application circuits. To minimize reflections, the
bus should be terminated at both ends in its characteristics
impedance, and stub lengths off the main line should be
kept as short as possible.
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16
Figure 10. Typical Isolated Half-Duplex RS-485 Application
RXD
RE
TXD
DE
RS-485 TRANSCEIVER
A
B
RXD
RE
TXD
DE
RS-485 TRANSCEIVER
A
B
RS-485 TRANSCEIVER
AB
RXDRETXD
DE
RS-485 TRANSCEIVER
AB
120120
INTEGRATED
ISOLATION
BARRIER
MAX14938
MAX14939
RXDRETXD
DE
Figure 11. Typical Isolated Profibus Application
PROFIBUS A LINE
PROFIBUS B LINE
RXD
RE
TXD
DE
RS-485 TRANSCEIVER
A
B
MAX14938
MAX14939
220Ω
390Ω
390Ω
V
LDO
V
DDB
V
DDA
1
1
2
2
2
F F
2
1µF
LDO
1
0.1µF
2
0.1µF
1µF
RXD
RE
TXD
DE
RS-485 TRANSCEIVER
A
B
220Ω
390Ω
390Ω
V
DDB
V
DDA
3
3
34
4
1µF
V
LDO
1µF
3
MAX14938
MAX14939
3
0.1µF
0.1µF
4
LDO
2
0.1µF
3
0.1µF
MAX14938/MAX14939 2.75kVRMS Isolated 20Mbps Half-Duplex PROFIBUS/
RS-485 Transceivers with ±35kV ESD Protection
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17
Profibus Termination
These devices are designed for driving PROFIBUS-DP
terminated networks. The driver maintains 2.1V (min)
when driving a worst-case loading condition of two
standard 220Ω termination resistors with 390Ω pullups/
pulldowns.
Layout Considerations
It is recommended to design an isolation, or “keep-out,”
channel underneath the isolator that is free from ground and
signal planes. Any galvanic or metallic connection between
the cable-side and UART-side will defeat the isolation.
Ensure that the decoupling capacitors between VDDA and
GNDA and between VLDO, VDDB, and GNDB are located
as close as possible to the IC to minimize inductance.
Route important signal lines close to the ground plane to
minimize possible external influences. On the cable-side
of the MAX14938/MAX14939, it is good practice to have
the bus connectors and termination resistor as close as
possible to the A and B pins.
Extended 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 MAX14938/MAX14939 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 and VLDO
to GNDB with 0.1μF and 1μF capacitors to ensure maxi-
mum ESD protection.
ESD protection can be tested in various ways. The
transmitter outputs and receiver inputs of the MAX14938/
MAX14939 are characterized for protection to the cable-
side ground (GNDB) to the following limits:
±35kV HBM
±12kV using the Air-Gap Discharge method specified
in IEC 61000-4-2
±10kV using the Contact Discharge method speci-
fied in IEC 61000-4-2
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 12 shows the HBM test model, while Figure
13 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.
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 MAX14938/
MAX14939 help in designing equipment to meet IEC
61000-4-2 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 14 shows the IEC 61000-4-2 model and
Figure 15 shows the current waveform for IEC 61000-4-2
ESD Contact Discharge Test.
MAX14938/MAX14939 2.75kVRMS Isolated 20Mbps Half-Duplex PROFIBUS/
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18
» o/x AAA [AAA c/ g "\* ************************* 4» +< suns="">
Figure 12. Human Body ESD Test Model Figure 13. Human Body Current Waveform
CHARGE-CURRENT-
LIMIT RESISTOR
DISCHARGE
RESISTANCE
STORAGE
CAPACITOR
Cs
100pF
RC
1M
RD
1500
HIGH-
VOLTAGE
DC
SOURCE
DEVICE
UNDER
TEST
IP 100%
90%
36.8%
tRL TIME
tDL
CURRENT WAVEFORM
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
Ir
10%
0
0
AMPS
Figure 14. IEC 61000-4-2 ESD Test Model Figure 15. IEC 61000-4-2 ESD Generator Current Waveform
CHARGE-CURRENT-
LIMIT RESISTOR
DISCHARGE
RESISTANCE
STORAGE
CAPACITOR
Cs
150pF
RC
50M TO 100M
RD
330
HIGH-
VOLTAGE
DC
SOURCE
DEVICE
UNDER
TEST
tr = 0.7ns TO 1ns 30ns
60ns
t
100%
90%
10%
IPEAK
I
MAX14938/MAX14939 2.75kVRMS Isolated 20Mbps Half-Duplex PROFIBUS/
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19
LDO
RS-485
TRANSCEIVER
V
DDA
RXD
TXD
DE
A
B
V
DDB
V
LDO
GNDA
(DEM)
GNDB
MAX14938
MAX14939
RE
ISOLATION BARRIER
µC
() MAX14938 only
* MAX14939 only
SBA*
(PV)
Typical Application Circuit
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Package Information
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
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND PATTERN
NO.
16 SOIC W16M+9 21-0042 90-0107
Ordering Information/Selector Guide
PART DEM PV SBA TEMP RANGE PIN-PACKAGE
MAX14938GWE+ -40°C to +105°C 16 SOIC (W)
MAX14938GWE+T -40°C to +105°C 16 SOIC (W)
MAX14939GWE+ — — -40°C to +105°C 16 SOIC (W)
MAX14939GWE+T — -40°C to +105°C 16 SOIC (W)
+Denotes lead(Pb)-free/RoHS-compliant package.
T = Tape & Reel
MAX14938/MAX14939 2.75kVRMS Isolated 20Mbps Half-Duplex PROFIBUS/
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21
Chip Information
PROCESS: BiCMOS
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 11/15 Initial release
1 1/17 Updated pending safety approvals 1, 7
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. © 2017Maxim Integrated Products, Inc.
22
MAX14938/MAX14939 2.75kVRMS Isolated 20Mbps Half-Duplex PROFIBUS/
RS-485 Transceivers with ±35kV ESD Protection
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.

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