MAX14770E
±35kV High-ESD Profibus RS-485 Transceiver
General Description
Benefits and Features
The MAX14770E is a half-duplex, Q35kV high ESDprotected, 20Mbps transceiver for PROFIBUS-DP and
RS-485 applications. In addition, it can be used for
RS-422/V.11 communications. The MAX14770E is
designed to meet IEC 61158-2, TIA/EIA-422-B, TIA/EIA485-A, V.11, and X.27 standards.
S Integrated Protection Increases Robustness
±35kV HBM ESD per JEDEC JS-001-2012
±12kV Contact ESD per IEC 61000-4-2
±15kV Air Gap ESD per IEC 61000-4-2
True Fail-Safe Receiver Prevents False
Transitions on Receiver Input Short or Open
Hot Swap Eliminates False Transitions During
Power-Up or Hot Insertion
Short-Circuit-Protected Outputs
Thermal Shutdown Circuitry Prevents Excessive
Power Dissipation
The MAX14770E is available in an 8-pin SO and an 8-pin
FMAX® specified over the extended temperature range.
It is also available in a tiny TDFN (3mm x 3mm) package and specified over the automotive (-40NC to +125NC)
temperature range.
Applications
PROFIBUS-DP Networks
S Low Current Reduces Power Consumption
15µA Shutdown Current
2.5mA Supply Current Typical with No Load
S Profibus Compliant with Minimum 20Mbps Data
Rate
S Allows Up to 128 Transceivers on the Bus
Industrial Fieldbuses
Motion Controllers
RS-485 Networks
S -40°C to +125°C Automotive Temperature Range
in Tiny 8-Pin (3mm x 3mm) TDFN
Machine Encoders
Ordering Information
PART
TEMP RANGE
PINPACKAGE
MAX14770EESA+T
-40NC to +85NC
8 SO
—
MAX14770EGSA+T
-40NC to +105NC 8 SO
—
MAX14770EGUA+T -40NC to +105NC 8 FMAX
Typical PROFIBUS-DP Operating Circuit appears at end of
data sheet.
TOP
MARK
MAX14770EATA+T
-40NC to +125NC 8 TDFN-EP*
—
BMG
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
*EP = Exposed pad.
Functional Diagram
RO
R
RE
A
SHUTDOWN
B
DE
DI
D
MAX14770E
The PROFIBUS PROCESS FIELD BUS logo is a registered
trademark of PROFIBUS and PROFINET International (PI).
µMAX is a registered trademark of Maxim Integrated Products, Inc.
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
19-5017; Rev 5; 1/15
MAX14770E
±35kV High-ESD Profibus RS-485 Transceiver
ABSOLUTE MAXIMUM RATINGS
(Voltages referenced to GND.)
VCC........................................................................-0.3V to +6.0V
RE, RO........................................................-0.3V to (VCC + 0.3V)
DE, DI....................................................................-0.3V to +6.0V
A, B......................................................................-8.0V to +13.0V
Short-Circuit Duration (RO, A, B) to GND..................Continuous
Continuous Power Dissipation (TA = +70NC)
SO (derate 7.6mW/NC above +70NC)..........................606mW
TDFN (derate 24.4mW/NC above +70NC)..................1951mW
FMAX (derate 4.8mW/NC above +70NC)...................387.8mW
Operating Temperature Range
MAX14470EESA...............................................-40NC to +85NC
MAX14470EG_A.............................................. -40NC to +105NC
MAX14470EATA.............................................. -40NC to +125NC
Storage Temperature Range............................. -65NC to +150NC
Junction Temperature Range............................ -40NC to +150NC
Lead Temperature (soldering, 10s).................................+300NC
Soldering Temperature (reflow).......................................+260NC
PACKAGE THERMAL CHARACTERISTICS (Note 1)
SO
Junction-to-Ambient Thermal Resistance (qJA).........132°C/W
Junction-to-Case Thermal Resistance (qJC)...............38°C/W
µMAX
Junction-to-Ambient Thermal Resistance (qJA)......206.3°C/W
Junction-to-Case Thermal Resistance (qJC)...............42°C/W
TDFN
Junction-to-Ambient Thermal Resistance (qJA)...........41°C/W
Junction-to-Case Thermal Resistance (qJC).................8°C/W
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.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VCC = +5V Q10%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V, TA = +25NC.) (Note 2)
PARAMETER
SYMBOL
Power-Supply Range
VCC
CONDITIONS
MIN
TYP
4.5
Supply Current
ICC
DE = 1, RE = 0 or
DE = 0, RE = 0 or
DE = 1, RE = 1; no load
Shutdown Supply
Current
ISH
DE = 0, RE = 1
2.5
MAX
UNITS
5.5
V
4
mA
15
FA
DRIVER
Differential Driver
Output
|VOD|
RL = 54I, DI = VCC or GND; Figure 1
2.1
Differential Driver
Peak-to-Peak Output
VODPP
Figure 2 (Note 3)
4.0
Change in Magnitude
of Differential Output
Voltage
DVOD
RL = 54I; Figure 1 (Note 4)
-0.2
Driver CommonMode Output Voltage
VOC
Change in CommonMode Voltage
DVOC
Driver Short-Circuit
Output Current
(Note 5)
IOSD
2
RL = 54I; Figure 1
RL = 54I; Figure 1 (Note 4)
-0.2
6.8
V
0
+0.2
V
1.8
3
V
+0.2
V
+250
0V P VOUT P +12V; output low
-7V P VOUT P VCC; output high
V
-250
mA
Maxim Integrated
MAX14770E
±35kV High-ESD Profibus RS-485 Transceiver
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +5V Q10%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V, TA = +25NC.) (Note 2)
PARAMETER
Driver Short-Circuit
Foldback Output
Current (Note 5)
SYMBOL
IOSDF
CONDITIONS
MIN
(VCC - 1V) P VOUT P +12V; output low
TYP
MAX
-15
+15
-7V P VOUT P +1V; output high
UNITS
mA
LOGIC INPUTS
Driver Input High
Voltage
VIH
DE, DI, RE
Driver Input Low
Voltage
VIL
DE, DI, RE
VHYS
DE, DI, RE
IIN
DE, DI, RE
Driver Input
Hysteresis
Driver Input Current
2.0
0.8
50
-1
RDE
Figure 11 until the first low-to-high transition of DE
occurs
RRE
Figure 11 until the first high-to-low transition of RE
occurs
Input Current (A, B)
IA, IB
DE = GND, VCC = VGND or
+5.5V
Differential Input
Capacitance
CAB
Between A and B, DE = RE = GND at 6MHz
Receiver Differential
Threshold Voltage
VTH
-7V P VCM P 12V
Input Impedance in
Hot Swap
V
1
mV
+1
5.6
V
10
FA
kW
RECEIVER
Receiver Input
Hysteresis
VIN = 12V
VIN = -7V
+250
-200
8
-200
DVTH
VCM = 0V
Output High Voltage
VOH
4
Output Low Voltage
VOL
IOUT = -6mA, VA - VB = VTH
IOUT = 6mA, VA - VB = -VTH
Three-State Receiver
Output Current
IOZR
0V P VOUT P VCC
-1
Receiver Input
Resistance
RIN
-7V P VCM P 12V
48
Receiver Output
Short-Circuit Current
IOSR
0V P VRO P VCC
-110
-125
FA
pF
-50
15
mV
mV
LOGIC OUTPUT
V
0.4
V
+1
FA
kI
+110
mA
PROTECTION SPECIFICATIONS
Thermal-Shutdown
Threshold
VTS
+160
NC
Thermal-Shutdown
Hysteresis
VTSH
15
NC
ESD Protection, A
and B Pins
Maxim Integrated
HBM
±35
IEC 61000-4-2 Air-Gap Discharge to GND
±20
IEC 61000-4-2 Contact Discharge to GND
±10
kV
3
MAX14770E
±35kV High-ESD Profibus RS-485 Transceiver
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +5V Q10%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V, TA = +25NC.) (Note 2)
PARAMETER
SYMBOL
ESD Protection, All
Other Pins
CONDITIONS
MIN
HBM
TYP
MAX
UNITS
kV
±2
DRIVER SWITCHING CHARACTERISTICS
Driver Propagation
Delay
tDPLH
tDPHL
RL = 54I, CL = 50pF; Figures 3 and 4
15
28
ns
Differential Driver
Output Skew |tDPLH
- tDPHL|
tDSKEW
RL = 54I, CL = 50pF; Figures 3 and 4
1.2
ns
Driver Output
Transition Skew
|tt(MLH)|, |tt(MHL)|
tTSKEW
RL = 54I, CL = 50pF; Figures 3 and 5
2
ns
Driver Differential
Output Rise or Fall
Time
tLH, tHL
RL = 54I, CL = 50pF; Figures 3 and 4
7
Maximum Data Rate
15
20
ns
Mbps
Driver Enable to
Output High
tDZH
RL = 500I, CL = 50pF; Figure 6
25
48
ns
Driver Enable to
Output Low
tDZL
RL = 500I, CL = 50pF; Figure 7
25
48
ns
Driver Disable Time
from Low
tDLZ
RL = 500I, CL = 50pF; Figure 7
20
40
ns
Driver Disable Time
from High
tDHZ
RL = 500I, CL = 50pF, Figure 6
20
40
ns
Driver Enable Skew
Time
|tZL - tZH|
RL = 500I, CL = 50pF; Figures 6 and 7
8
ns
Driver Disable Skew
Time
|tLZ - tHZ|
RL = 500I, CL = 50pF; Figures 6 and 7
8
ns
Driver Enable High—
Propagation Delay
Difference
tDZH tDPHL
8
20
ns
Driver Enable Low—
Propagation Delay
Difference
tDZL - tDPHL
10
20
ns
Driver Enable from
Shutdown to Output
High
tDZL(SHDN)
RL = 500I, CL = 50pF; Figure 7 (Note 6)
46
100
Fs
Driver Enable from
Shutdown to Output
Low
tDZH(SHDN)
RL = 500I, CL = 50pF; Figure 6 (Note 6)
46
100
Fs
800
ns
Time to Shutdown
4
tSHDN
(Note 6)
50
Maxim Integrated
MAX14770E
±35kV High-ESD Profibus RS-485 Transceiver
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +5V Q10%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V, TA = +25NC.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
CL = 15pF; Figures 8 and 9 (Note 7)
28
ns
CL = 15pF; Figures 8 and 9 (Notes 7, 8)
2
ns
RECEIVER SWITCHING CHARACTERISTICS
Receiver Propagation
Delay
Receiver Output
Skew
tRPLH
tRPHL
tRSKEW
Maximum Data Rate
20
Mbps
Receiver Enable to
Output High
tRZH
S2 closed; RL = 1kI, CL = 15pF; Figure 10
30
ns
Receiver Enable to
Output Low
tRZL
S1 closed; RL = 1kI, CL = 15pF; Figure 10
30
ns
Receiver Disable
Time from Low
tRLZ
S1 closed; RL = 1kI, CL = 15pF; Figure 10
30
ns
Receiver Disable
Time from High
tRHZ
S2 closed; RL = 1kI, CL = 15pF; Figure 10
30
ns
Receiver Enable from
Shutdown to Output
High
tRZL(SHDN)
S1 closed; RL = 1kI, CL = 15pF; Figure 10
(Notes 6, 7)
100
Fs
Receiver Enable from
Shutdown to Output
Low
tRZH(SHDN)
S2 closed; RL = 1kI, CL = 15pF; Figure 10
(Notes 6, 7)
100
Fs
800
ns
Time to Shutdown
tSHDN
(Note 6)
50
2: Devices are production tested at TA = +25NC. Specifications over temperature limits are guaranteed by design.
3: VODPP is the difference in VOD, with the DI at high and DI at low.
4: DVOD and DVOC are the changes in |VOD| and |VOC|, respectively, with the DI at high and DI at low.
5: The short-circuit output current applies to peak current just prior to foldback current limiting; the short-circuit foldback output current applies during current limiting to allow a recovery from bus contention.
Note 6: Shutdown is enabled by bringing RE high and DE 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 in this state for at least 800ns, the device is guaranteed to
have entered shutdown.
Note 7: Capacitive load includes test probe and fixture capacitance.
Note 8: Guaranteed by characterization; not production tested.
Note
Note
Note
Note
Maxim Integrated
5
MAX14770E
±35kV High-ESD Profibus RS-485 Transceiver
VCC
A
VCC
DE
RL
2
195I
A
DI
VOD
RL
2
110I
VOD
B
VOC
195I
B
Figure 1. Driver DC Test Load
Figure 2. VODPP Swing Under Profibus Equivalent Load Test
VCC
DE
DI
A
VID
B
RL
CL
Figure 3. Driver Timing Test Circuit
f = 1MHz, tLH P 3ns, tHL P 3ns
VCC
1.5V
DI
1.5V
0
1/2 VO
tDPHL
tDPLH
B
A
1/2 VO
VO
VDIFF = VA - VB
VO
VDIFF
80%
80%
0
-VO
20%
20%
tLH
tHL
tDSKEW = |tDPLH - tDPHL|
Figure 4. Driver Propagation Delays
6
Maxim Integrated
MAX14770E
±35kV High-ESD Profibus RS-485 Transceiver
50%
50%
A
tt(MHL)
tt(MLH)
B
50%
50%
Figure 5. Driver Transition Skew
A
0 OR VCC DI D
B
S1
VCC
OUT
CL
50pF
DE
RL = 500I
1.5V
tDZH, tDZH(SHDN)
DE
GENERATOR
0.25V
1.5V
OUT
50I
tDHZ
0
VOH
0
Figure 6. Driver Enable and Disable Times
VCC
0 OR VCC DI D
A
RL = 500I
S1
OUT
B
DE
GENERATOR
50I
VCC
DE
tDZL, tDZL(SHDN)
1.5V
0
tDLZ
VCC
OUT
VOL
1.5V
0.25V
Figure 7. Driver Enable and Disable Times
Maxim Integrated
7
MAX14770E
±35kV High-ESD Profibus RS-485 Transceiver
A
ATE
RECEIVER
OUTPUT
R
VID
B
Figure 8. Receiver Propagation Delay Test Circuit
t = 1MHz, tLH P 3ns, tHL P 3ns
A
1V
B
-1V
tRPHL
VOH
tRPLH
VCC
2
RO
VOL
VCC
2
tRSKEW = |tRPHL - tRPLH|
Figure 9. Receiver Propagation Delays
+1.5V
S3
-1.5V
VID
R
RE
GENERATOR
RO
R
1kI
S1
VCC
S2
CL
15pF
50I
VCC
1.5V
RE
tRZH, tRZH (SHDN)
0
VCC
S1 OPEN
S2 CLOSED
S3 = +1.5V
1.5V
RE
0
S1 CLOSED
S2 OPEN
S3 = -1.5V
tRZL, tRZL(SHDN)
RO
VOH
VCC
2
0
VCC
1.5V
RE
0
VCC
2
0.25V
VOL
RO
VCC
S1 OPEN
S2 CLOSED
S3 = +1.5V
1.5V
S1 CLOSED
S2 OPEN
S3 = -1.5V
0
RE
tRLZ
tRHZ
RO
VCC
VCC
VOH
0
RO
0.25V
VOL
Figure 10. Receiver Enable and Disable Times
8
Maxim Integrated
MAX14770E
±35kV High-ESD Profibus RS-485 Transceiver
Typical Operating Characteristics
(VCC = +5V, TA = +25NC, unless otherwise noted.)
SUPPLY CURRENT
vs. DATA RATE
DE = GND
1.0
0.5
-40 -25 -10 5 20 35 50 65 80 95 110 125
NO LOAD
15
10
1.5
1.0
0.5
0
5,000
0
10,000
15,000
-40 -25 -10 5 20 35 50 65 80 95 110 125
20,000
TEMPERATURE (°C)
RECEIVER OUTPUT RO CURRENT
vs. OUTPUT LOW VOLTAGE
RECEIVER OUTPUT RO CURRENT
vs. OUTPUT HIGH VOLTAGE
RECEIVER PROPAGATION DELAY
vs. TEMPERATURE
20
40
30
20
10
10
0
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
MAX14770E toc06
25
RECEIVER PROPAGATION DELAY (ns)
50
OUTPUT CURRENT (mA)
30
MAX14770E toc05
60
MAX14770E toc04
40
20
15
10
5
0
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
-40 -25 -10 5 20 35 50 65 80 95 110 125
5.0
TEMPERATURE (°C)
DRIVER PROPAGATION DELAY
vs. TEMPERATURE
DIFFERENTIAL OUTPUT VOLTAGE VOD
vs. OUTPUT CURRENT
DIFFERENTIAL OUTPUT VOLTAGE VOD
vs. TEMPERATURE
15
10
5
0
MAX14770E toc08
20
4.0
DIFFERENTIAL OUTPUT VOLTAGE (V)
RL = 54Ω, CL = 50pF
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
Maxim Integrated
2.8
RL = 54Ω
2.7
2.6
MAX14770E toc09
OUTPUT HIGH VOLTAGE (V)
DRIVER DIFFERENTIAL OUTPUT VOLTAGE (V)
OUTPUT LOW VOLTAGE (V)
MAX14770E toc07
0
2.0
DATA RATE (kbps)
50
OUTPUT CURRENT (mA)
30
25
20
2.5
TEMPERATURE (°C)
60
DRIVER PROPAGATION DELAY (ns)
PROFIBUS EQUIVALENT LOAD
40
35
5
0
0
25
45
3.0
MAX14770E toc03
55
50
SUPPLY CURRENT (mA)
2.0
MAX14770E toc02
DE = VCC
1.5
60
MAX14770E toc01
NO-LOAD SUPPLY CURRENT (mA)
2.5
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
SHUTDOWN SUPPLY CURRENT (µA)
NO-LOAD DC SUPPLY CURRENT
vs. TEMPERATURE
2.5
2.4
2.3
2.2
2.1
2.0
0
20
40
60
OUTPUT CURRENT (mA)
80
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
9
MAX14770E
±35kV High-ESD Profibus RS-485 Transceiver
Typical Operating Characteristics (continued)
(VCC = +5V, TA = +25NC, unless otherwise noted.)
100
80
60
40
20
3
6
9
60
40
12
RL = 54Ω, CL = 50pF
4
3
2
1
0
-7
-5
-3
-1
1
3
-40 -25 -10 5 20 35 50 65 80 95 110 125
5
OUTPUT HIGH VOLTAGE (V)
TEMPERATURE (°C)
DRIVER OUTPUT TRANSITION SKEW
vs. TEMPERATURE
DRIVER OUTPUT RISE AND FALL TIME
vs. TEMPERATURE
DRIVER ENABLE TO
OUTPUT HIGH tDZH
RL = 54Ω, CL = 50pF
16
4
2
FALL TIME
12
TIME (ns)
3
14
RL = 54Ω, CL = 50pF
10
MAX14770E toc14
OUTPUT LOW VOLTAGE (V)
MAX14770E toc13
DRIVER OUTPUT TRANSITION SKEW (ns)
80
0
0
MAX14770E toc15
DI = VCC, RL = 500Ω, CL = 50pF
DE
2V/div
RISE TIME
8
6
4
1
2
0
A
2V/div
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
TEMPERATURE (°C)
DRIVER ENABLE TO
OUTPUT LOW tDZL
DRIVER DISABLE TIME
FROM LOW tDLZ
MAX14770E toc16
10ns/div
10ns/div
DRIVER DISABLE TIME
FROM HIGH tDHZ
MAX14770E toc17
DI = VCC, RL = 500Ω, CL = 50pF
10
100
5
20
0
5
MAX14770E toc11
120
OUTPUT CURRENT (mA)
120
OUTPUT CURRENT (mA)
140
MAX14770E toc10
140
DRIVER DIFFERENTIAL SKEW tDSKEW
vs. TEMPERATURE
MAX14770E toc12
DRIVER OUTPUT CURRENT
vs. OUTPUT HIGH VOLTAGE
DRIVER OUTPUT SKEW (ns)
DRIVER OUTPUT CURRENT
vs. OUTPUT LOW VOLTAGE
MAX14770E toc18
DI = VCC, RL = 500Ω, CL = 50pF
DI = VCC, RL = 500Ω, CL = 50pF
DE
2V/div
DE
2V/div
B
2V/div
B
2V/div
10ns/div
DE
2V/div
A
2V/div
10ns/div
Maxim Integrated
MAX14770E
±35kV High-ESD Profibus RS-485 Transceiver
Pin Configurations
TOP VIEW
+
RO
1
RE
2
+
MAX14770E
8 VCC
RO
1
7 B
RE
2
DE 3
6
A
DE
3
DI
5 GND
DI
4
4
SO/µMAX
8
VCC
7
B
6
A
5
GND
MAX14770E
*EP
TDFN
(3mm × 3mm)
*CONNECT EXPOSED PAD TO GND.
Pin Description
PIN
NAME
1
RO
Receiver Output. When RE is low and (A - B) R -50mV, RO is high; if (A - B) P -200mV, RO is low.
2
RE
Receiver Enable. Drive RE low to enable RO; RO is high impedance when RE is high. Drive RE
high and DE low to enter low-power shutdown mode.
3
DE
Driver Enable. Drive DE high to enable driver output. The driver outputs are high impedance when
DE is low. Drive RE high and DE low to enter low-power shutdown mode.
4
DI
Driver Input. With DE high, a low on DI forces the noninverting output, A, low and the inverting output, B, high. Similarly, a high on DI forces the noninverting output, A, high and the inverting output,
B, low.
5
GND
6
A
Noninverting Receiver Input and Noninverting Driver Output
7
B
Inverting Receiver Input and Inverting Driver Output
8
VCC
—
EP
Maxim Integrated
FUNCTION
Ground
Positive Supply. Bypass VCC to GND with a 0.1FF ceramic capacitor as close as possible to the
device.
Exposed Pad (TDFN Only). Connect EP to GND.
11
MAX14770E
±35kV High-ESD Profibus RS-485 Transceiver
Detailed Description
The MAX14770E is a half-duplex, Q35kV high ESDprotected transceiver for PROFIBUS-DP, RS-485, and
RS-422 communications. The device features true failsafe circuitry that guarantees a logic-high receiver
output when the receiver inputs are open or shorted,
or when they are connected to a terminated transmission line with all drivers disabled (see the True Fail-Safe
section). The MAX14770E supports data rates up to
20Mbps.
The MAX14770E operates from a single +4.5V to +5.5V
supply. Drivers are output short-circuit current limited. Thermal-shutdown circuitry protects drivers against
excessive power dissipation. When activated, the thermal-shutdown circuitry places the driver outputs into
a high-impedance state. The MAX14770E has a hotswap input structure that prevents disturbances on the
differential signal lines when the MAX14770E is powered
up (see the Hot-Swap Capability section).
True Fail-Safe
The MAX14770E 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. This is done by having the receiver
Table 1. Functional Table (Transmitting)
TRANSMITTING
INPUTS
OUTPUTS
RE
X
DE
DI
B
A
1
1
0
1
X
1
0
1
0
0
0
X
High-Z
High-Z
1
0
X
High-Z and shutdown
X = Don’t care.
Table 2. Functional Table (Receiving)
RECEIVING
INPUTS
OUTPUT
RE
0
DE
A-B
RO
X
R -0.05V
1
0
X
P -0.2V
0
0
X
Open/shorted
1
1
1
X
High-Z
1
0
X
High-Z and
shutdown
X = Don’t care.
12
threshold between -50mV and -200mV. If the differential
receiver input voltage (A - B) is greater than or equal to
-50mV, RO is logic-high. If (A - B) is less than or equal to
-200mV, RO is logic-low. In the case of a terminated bus
with all transmitters disabled, the receiver’s differential
input voltage is pulled to 0V by the termination. With
the receiver thresholds of the MAX14770E, this results
in a logic-high with a 50mV minimum noise margin. The
-50mV to -200mV threshold complies with the Q200mV
EIA/TIA-485 standard.
Hot-Swap Capability
Hot-Swap Inputs
When circuit boards are inserted into a hot or powered
backplane, disturbances to the enable inputs and differential receiver inputs can lead to data errors. Upon initial
circuit board insertion, the processor undergoes its power-up sequence. During this period, the processor output drivers are high impedance and are unable to drive
the DE and RE inputs of the MAX14770E to a defined
logic level. Leakage currents up to 10FA from the highimpedance output of a controller could cause DE and RE
to drift to an incorrect logic state. Additionally, parasitic
circuit board capacitance could cause coupling of VCC
or GND to DE and RE. These factors could improperly
enable the driver or receiver. However, the MAX14770E
has hot-swap inputs that avoid these potential problems.
When VCC rises, an internal pulldown circuit holds DE
low and RE high. After the initial power-up sequence,
the pulldown circuit becomes transparent, resetting the
hot-swap-tolerable inputs.
Hot-Swap Input Circuitry
The MAX14770E DE and RE enable inputs feature
hot-swap capability. At the input, there are two NMOS
devices, M1 and M2 (Figure 11). When VCC ramps from
0, an internal 15Fs timer turns on M2 and sets the SR
latch that also turns on M1. Transistors M2, a 1mA current sink, and M1, a 100FA current sink, pull DE to GND
through a 5.6kI resistor. M2 is designed to pull DE to
the disabled state against an external parasitic capacitance up to 100pF that can drive DE high. After 15Fs, the
timer deactivates M2 while M1 remains on, holding DE
low against three-state leakages that can drive DE high.
M1 remains on until an external source overcomes the
required input current. At this time, the SR latch resets
and M1 turns off. When M1 turns off, DE reverts to a
standard, high-impedance CMOS input. Whenever VCC
drops below 1V, the hot-swap input is reset.
For RE, there is a complementary circuit employing two
PMOS devices pulling RE to VCC.
Maxim Integrated
MAX14770E
±35kV High-ESD Profibus RS-485 Transceiver
Thermal-Shutdown Protection
The MAX14770E features thermal-shutdown circuitry.
The internal switch turns off when the junction temperature exceeds +160NC (typ) and immediately goes into a
fault mode. The device exits thermal shutdown after the
junction temperature cools by 15NC (typ).
Applications Information
128 Transceivers on the Bus
The standard RS-485 receiver input impedance is one
unit load, and a standard driver can drive up to 32 unit
loads. The MAX14770E transceiver has a 1/4 unit load
receiver, which allows up to 128 transceivers connected
in parallel on one communication line. Connect any combination of these devices, and/or other RS-485 devices,
for a maximum of 32 unit loads to the line.
Low-Power Shutdown Mode
Low-power shutdown mode is initiated by bringing both
RE high and DE low. In shutdown, the devices draw only
15FA (max) of supply current. RE and DE can be driven
simultaneously; the devices are guaranteed not to enter
shutdown if RE is high and DE is low for less than 50ns. If
the inputs are in this state for at least 800ns, the devices
are guaranteed to enter shutdown.
Driver Output Protection
Two mechanisms prevent excessive output current and
power dissipation caused by faults or by bus contention. The first, a foldback current limit on the output
stage, provides immediate protection against short circuits over the whole common-mode voltage range (see
the Typical Operating Characteristics). The second, a
thermal-shutdown circuit, forces the driver outputs into
a high-impedance state if the die temperature exceeds
+160NC (typ).
Typical Application
The MAX14770E transceivers are designed for bidirectional
data communications on multipoint bus transmission lines.
Figure 12 shows a typical network applications circuit. To
minimize reflections, the line should be terminated at both
ends in its characteristic impedance, and stub lengths off
the main line should be kept as short as possible.
Profibus Termination
The MAX14770E is designed for driving PROFIBUS-DP
termination networks. With a worst-case loading of two
termination networks with 220I termination impedance
and 390I pullups/pulldowns, the drivers can drive
V(A - B) > 2.1V output.
VCC
15Fs
TIMER
TIMER
DE
DRIVER
ENABLE
(HOT SWAP)
5.6kI
100FA
M1
1mA
M2
Figure 11. Simplified Structure of the Driver Enable Pin (DE)
Maxim Integrated
13
MAX14770E
±35kV High-ESD Profibus RS-485 Transceiver
120I
DI
120I
DE
B
B
D
D
A
DE
B
RO
A
B
DI
A
A
R
R
RE
RO
RE
MAX14770E
R
D
DI
DE
RO RE
R
D
DI
DE
RO RE
Figure 12. Typical Half-Duplex RS-485 Network
RC
1MI
CHARGE-CURRENTLIMIT RESISTOR
HIGHVOLTAGE
DC
SOURCE
CS
100pF
RD
1.5kI
IP 100%
90%
DISCHARGE
RESISTANCE
STORAGE
CAPACITOR
IR
AMPERES
DEVICE
UNDER
TEST
36.8%
10%
0
0
Figure 13. Human Body ESD Test Model
Extended ESD Protection
ESD protection structures are incorporated on all pins
to protect against electrostatic discharges up to Q2kV
(HBM) encountered during handling and assembly.
A and B are further protected against high ESD up
to Q35kV (HBM) without damage. The A and B pins
are also protected against Q20kV Air-Gap and Q10kV
Contact IEC61000-4-2 ESD events. The ESD structures
withstand high ESD both in normal operation and when
the device is powered down. After an ESD event, the
MAX14770E continues to function without latchup.
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.
14
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
tRL
TIME
tDL
CURRENT WAVEFORM
Figure 14. Human Body Current Waveform
Human Body Model
Figure 13 shows the HBM. Figure 14 shows the current
waveform it generates when discharged into a lowimpedance state. This model consists of a 100pF capacitor charged to the ESD voltage of interest that is then
discharged into the device through a 1.5kI resistor.
IEC 61000-4-2
The IEC 61000-4-2 standard covers ESD testing and
performance of finished equipment. It does not specifically refer to integrated circuits. The MAX14770E
is specified for Q20kV Air-Gap Discharge and Q10kV
Contact Discharge IEC 61000-4-2 on the A and B pins.
The main 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
Maxim Integrated
MAX14770E
±35kV High-ESD Profibus RS-485 Transceiver
RC
50MI TO 100MI
RD
330I
CS
150pF
IPEAK
DISCHARGE
RESISTANCE
CHARGE-CURRENTLIMIT RESISTOR
HIGHVOLTAGE
DC
SOURCE
100%
90%
DEVICE
UNDER
TEST
STORAGE
CAPACITOR
10%
t
tR = 0.7ns
TO 1ns
30ns
60ns
Figure 15. IEC61000-4-2 ESD Test Model
Figure 16. IEC61000-4-2 ESD Generator Current Waveform
Typical PROFIBUS-DP Operating Circuit
VCC
RO
0.1FF
R
VCC
0.1FF
390I
DI
D
390I
RE
A
SHUTDOWN
220I
SHUTDOWN
B
DE
DI
D
DE
A
PROFIBUS B LINE
220I
PROFIBUS A LINE
B
390I
RE
RO
R
390I
MAX14770E
MAX14770E
GND
GND
ESD test model (Figure 15), the ESD-withstand voltage
measured to this standard is generally lower than that
measured using the HBM. Figure 16 shows the current
waveform for the Q10kV IEC 61000-4-2 Level 4 ESD
Contact Discharge test. The Air-Gap Discharge test
involves approaching the device with a charged probe.
The Contact Discharge method connects the probe to
the device before the probe is energized.
Chip Information
PROCESS: BiCMOS
Maxim Integrated
Package Information
For the latest package outline information and land patterns, 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.
8 SO
S8+4
21-0041
90-0096
8 TDFN-EP
T833+2
21-0137
90-0059
8 FMAX
U8+1
21-0036
90-0092
15
MAX14770E
±35kV High-ESD Profibus RS-485 Transceiver
Revision History
REVISION
NUMBER
REVISION
DATE
0
10/09
Initial release
—
1
4/10
Switched the position of the pins DE and DI (TDFN) in the Pin Configurations
11
2
1/11
Updated logic output specifications, TOC 15, and the Typical PROFIBUS-DP
Operating Circuit, added the “Driver Enable High/Low—Propagation Delay
Difference” parameters and updated various typical values in the Electrical
Characteristics table
3, 4, 10, 15
3
10/12
Added FMAX and new SO packaging to data sheet
1, 2, 11, 15
4
2/13
Added missing 85°C SO information to data sheet
1, 2
5
1/15
Updated document title and General Description and Benefits and Features sections
1-16
DESCRIPTION
PAGES
CHANGED
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.
16
© 2015
Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000
Maxim Integrated Products, Inc.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
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