19-5652; Rev 1; 7/11
+5.0V, ±30kV ESD-Protected, Fail-Safe,
Hot-Swap, RS-485/RS-422 Transceiver
General Description
The MAX14780E +5.0V, ±30kV ESD-protected, RS-485/
RS-422 transceiver features one driver and one receiver.
The device includes fail-safe circuitry, guaranteeing a
logic-high receiver output when receiver inputs are open
or shorted. The receiver outputs a logic-high if all trans-
mitters on a terminated bus are disabled (high imped-
ance). The MAX14780E includes a hot-swap capability
to eliminate false transitions on the bus during power-up
or hot insertion.
The MAX14780E features reduced slew-rate drivers that
minimize EMI and reduce reflections caused by improp-
erly terminated cables, allowing error-free data transmis-
sion up to 500kbps.
The MAX14780E is ideal for half-duplex communications
and it draws 1.2mA of supply current when unloaded
or when fully loaded with the drivers disabled. The
MAX14780E has a 1/8-unit load receiver input imped-
ance, allowing up to 256 transceivers on the bus.
The MAX14780E is available in an 8-pin SO and PDIP
packages.
S
+5.0V Operation
S
Extended ESD Protection for RS-485/RS-422 I/O
Pins ±30kV Human Body Model
S
True Fail-Safe Receiver While Maintaining EIA/
TIA-485 Compatibility
S
Hot-Swap Input Structures on DE and
RE
S
Enhanced Slew-Rate Limiting Facilitates Error-
Free Data Transmission
S
Low-Current Shutdown Mode
S
Allow Up to 256 Transceivers on the Bus
S
Available in Industry-Standard 8-Pin SO and PDIP
Packages
Features
MAX14780E
Applications
Utility Meters
Lighting Systems
Industrial Control
Telecom
Security Systems
Instrumentation
Profibus
PART
MAX14780EESA+
MAX14780EEPA+
Ordering Information
TEMP RANGE
-40NC to +85NC
-40NC to +85NC
PIN-PACKAGE
8 SO
8 PDIP
+Denotes
a lead(Pb)-free/RoHS-compliant package.
Typical Operating Circuit
0.1µF
RO
RE
DE
DI
1
2
3
4
D
+
MAX14780E
DE
D
DI
R
8
7
6
5
V
CC
B
A
GND
Rt
B
Rt
A
R
RO
RE
TYPICAL HALF-DUPLEX OPERATING CIRCUIT
_______________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
+5.0V, ±30kV ESD-Protected, Fail-Safe,
Hot-Swap, RS-485/RS-422 Transceiver
MAX14780E
ABSOLUTE MAXIMUM RATINGS
(All voltages referenced to GND.)
Supply Voltage (V
CC
) ........................................................... +6V
Control Input Voltage (RE, DE) ...............................-0.3V to +6V
Driver Input Voltage (DI) .........................................-0.3V to +6V
Driver Output Voltage (A, B) ....................................-8V to +13V
Receiver Input Voltage (A, B) ..................................-8V to +13V
Receiver Output Voltage (RO) ................. -0.3V to (V
CC
+ 0.3V)
Driver Output Current .................................................... ±250mA
Continuous Power Dissipation (T
A
= +70°C)
SO (derate 5.9mW/°C above +70°C) ..........................471mW
PDIP (derate 9.1mW/°C above +70°C) .....................727.3mW
Operating Temperature Range .......................... -40°C to +85°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.
DC ELECTRICAL CHARACTERISTICS
(V
CC
= +5.0V ±10%, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC
= +5.0V and T
A
= +25NC.) (Note 1)
PARAMETER
DRIVER
V
CC
Supply-Voltage Range
Differential Driver Output
Change in Magnitude of
Differential Output Voltage
Driver Common-Mode Output
Voltage
Change in Magnitude of
Common-Mode Voltage
Input-High Voltage
Input-Low Voltage
Input Hysteresis
Input Current
Input Impedance First Transition
Driver Short-Circuit Output
Current
Driver Short-Circuit Foldback
Output Current
Thermal-Shutdown Threshold
Thermal-Shutdown Hysteresis
Input Current (A and B)
RECEIVER
Receiver Differential Threshold
Voltage
Receiver Input Hysteresis
V
TH
DV
TH
-7V
P
V
CM
P
+12V
V
A
+ V
B
= 0V
-200
-125
15
-50
mV
mV
I
OSD
I
OSDF
T
TS
T
TSH
I
A, B
V
DE
= 0V,
V
CC
= 0V or V
CC
V
IN
= +12V
V
IN
= -7V
-100
V
CC
R
L
= 100I (RS-422), Figure 1
V
OD
R
L
= 54I (RS-485), Figure 1
No load
DV
OD
V
OC
DV
OC
V
IH
V
IL
V
HYS
I
IN1
R
L
= 100I or 54I, Figure 1 (Note 2)
R
L
= 100I or 54I, Figure 1
R
L
= 100I or 54I, Figure 1 (Note 2)
DE, DI,
RE
DE, DI,
RE
DE, DI,
RE
DE, DI,
RE
DE,
RE
0
P
V
OUT
P
+12V (Note 3)
-7V
P
V
OUT
P
V
CC
(Note 3)
(V
CC
- 1V)
P
V
OUT
P
+12V (Note 3)
-7V
P
V
OUT
P
+1V (Note 3)
175
15
125
1
40
-250
20
-20
100
Q1
10
250
-40
3
0.8
V
CC
/2
4.5
3
2
5.5
V
CC
V
CC
V
CC
0.2
3
0.2
V
V
V
V
V
mV
FA
kI
mA
mA
NC
NC
FA
V
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
2
______________________________________________________________________________________
+5.0V, ±30kV ESD-Protected, Fail-Safe,
Hot-Swap, RS-485/RS-422 Transceiver
DC ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +5.0V ±10%, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC
= +5.0V and T
A
= +25NC.) (Note 1)
PARAMETER
RO Output-High Voltage
RO Output-Low Voltage
Three-State Output Current at
Receiver
Receiver Input Resistance
Receiver Output Short-Circuit
Current
SUPPLY CURRENT
No load, V
RE
= 0V, DE = V
CC
Supply Current
Supply Current in Shutdown
Mode
ESD PROTECTION
Human Body Model
ESD Protection for A and B
Contact Discharge
IEC 61000-4-2
Air-Gap Discharge
IEC 61000-4-2
Q30
Q12
Q15
kV
I
CC
No load,
RE
= V
CC
, DE = V
CC
No load, V
RE
= 0V, V
DE
= 0V
RE
= V
CC
, V
DE
= 0V
1.2
1.2
1.2
2.8
1.8
1.8
1.8
10
FA
mA
SYMBOL
V
OH
V
OL
I
OZR
R
IN
I
OSR
I
O
= -1mA
I
O
= 1mA
0
P
V
O
P
V
CC
-7V
P
V
CM
P
+12V
0V
P
V
RO
P
V
CC
96
P
110
CONDITIONS
MIN
V
CC
-
0.6
TYP
MAX
V
0.4
P
1
V
FA
kI
mA
UNITS
MAX14780E
I
SHDN
DRIVER SWITCHING CHARACTERISTICS WITH INTERNAL SRL (500kbps)
(V
CC
= +5.0V ±10%, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC
= +5.0V and T
A
= +25NC.) (Note 1)
PARAMETER
Driver Propagation Delay
Driver Differential Output Rise or
Fall Time
Differential Driver Output Skew
|t
DPLH
- t
DPHL
|
Maximum Data Rate
Driver Enable to Output High
Driver Enable to Output Low
Driver Disable Time from Low
Driver Disable Time from High
Driver Enable from Shutdown to
Output High
Driver Enable from Shutdown to
Output Low
Time to Shutdown
t
DZH
t
DZL
t
DLZ
t
DHZ
Figure 4
Figure 5
Figure 5
Figure 4
SYMBOL
t
DPLH
t
DPHL
t
R ,
t
F
t
DSKEW
CONDITIONS
C
L
= 50pF, R
L
= 54I, Figures 2 and 3
C
L
= 50pF, R
L
= 54I, Figures 2 and 3
C
L
= 50pF, R
L
= 54I, Figures 2 and 3
500
2500
2500
100
100
5500
5500
50
340
700
MIN
200
200
250
TYP
MAX
1000
1000
900
140
UNITS
ns
ns
ns
kbps
ns
ns
ns
ns
ns
ns
ns
t
DZH(SHDN)
Figure 4
t
DZL(SHDN)
Figure 5
t
SHDN
_______________________________________________________________________________________
3
+5.0V, ±30kV ESD-Protected, Fail-Safe,
Hot-Swap, RS-485/RS-422 Transceiver
MAX14780E
RECEIVER SWITCHING CHARACTERISTICS WITH INTERNAL SRL (500kbps)
(V
CC
= +5.0V ±10%, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC
= +5.0V and T
A
= +25NC.) (Note 1)
PARAMETER
Receiver Propagation Delay
Receiver Output Skew
|t
RPLH
- t
RPHL
|
Maximum Data Rate
Receiver Enable to Output Low
Receiver Enable to Output High
Receiver Disable Time from Low
Receiver Disable Time from High
Receiver Enable from Shutdown
to Output High
Receiver Enable from Shutdown
to Output Low
Time to Shutdown
t
RZL
t
RZH
t
RLZ
t
RHZ
Figure 8
Figure 8
Figure 8
Figure 8
SYMBOL
t
RPLH
t
RPHL
t
RSKEW
CONDITIONS
C
L
= 15pF, Figures 6 and 7
C
L
= 15pF, Figures 6 and 7
500
50
50
50
50
5500
5500
50
340
700
MIN
TYP
MAX
200
200
30
UNITS
ns
ns
kbps
ns
ns
ns
ns
ns
ns
ns
t
RZH(SHDN)
Figure 8
t
RZL(SHDN)
Figure 8
t
SHDN
Note 1:
All currents into the device are positive. All currents out of the device are negative. All voltages are referred to device
ground, unless otherwise noted.
Note 2:
ΔV
OD
and ΔV
OC
are the changes in V
OD
and V
OC
, respectively, when the DI input changes state.
Note 3:
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.
Test Circuits and Waveforms
B
R
L
/2
V
OD
R
L
/2
A
V
OC
Z
Y
V
O
V
DIFF
0
-V
O
V
O
1/2 V
O
10%
t
R
t
SKEW
= | t
DPLH
- t
DPHL
|
90%
t
F
DI
0
V
CC
V
CC
/2
t
DPLH
t
DPHL
1/2 V
O
V
DIFF
= V (B) - V (A)
90%
10%
Figure 1. Driver DC Test Load
V
CC
DE
B
DI
A
V
OD
R
L
C
L
Figure 3. Driver Propagation Delays
Figure 2. Driver Timing Test Circuit
4
______________________________________________________________________________________
+5.0V, ±30kV ESD-Protected, Fail-Safe,
Hot-Swap, RS-485/RS-422 Transceiver
Test Circuits and Waveforms (continued)
S1
0 OR V
CC
D
C
L
50pF
OUT
R
L
= 500Ω
MAX14780E
GENERATOR
50Ω
V
CC
DE
t
DZH
, t
DZH(SHDN)
V
CC
/2
0
0.25V
OUT
V
OM
= (0 + V
OH
)/2
t
DHZ
0
V
OH
Figure 4. Driver Enable and Disable Times (t
DHZ
, t
DZH
, t
DZH(SHDN)
)
V
CC
R
L
= 500Ω
OUT
C
L
50pF
S1
0 OR V
CC
D
GENERATOR
50Ω
V
CC
DE
t
DZL
, t
DZL(SHDN)
V
CC
/2
0
t
DLZ
V
OM
= (V
OL
+ V
CC
)/2
V
OL
0.25V
V
CC
OUT
Figure 5. Driver Enable and Disable Times (t
DZL
, t
DLZ,
t
DLZ(SHDN)
)
_______________________________________________________________________________________
5
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