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DATASHEET
±15kV ESD Protected, 3.3V, Full Fail-Safe, Low Power,
High Speed or Slew Rate Limited, RS-485/RS-422
Transceivers
ISL3178AE
Features
The Intersil ISL3178AE is ±15kV IEC61000 ESD protected,
3.3V-powered, single transceiver that meets both the RS-485
and RS-422 standards for balanced communication. This
device has very low bus currents (+125µA/-100µA), which
presents a true “1/8 unit load” to the RS-485 bus. This allows up
to 256 transceivers on the network without violating the RS-485
specification’s 32 unit load maximum, and without using
repeaters. For example, in a remote utility meter reading
system, individual meter readings are routed to a concentrator
via an RS-485 network, so the high allowed node count
minimizes the number of repeaters required.
• IEC61000 ESD protection on RS-485 I/O pins . . . . . . . ±15kV
- Class 3 ESD level on all other pins. . . . . . . . . . . .>7kV HBM
Receiver (Rx) inputs feature a “Full Fail-Safe” design, which
ensures a logic high Rx output if Rx inputs are floating,
shorted, or terminated but undriven.
• Full fail-safe (open, short, terminated/floating) receivers
• Hot plug - Tx and Rx outputs remain three-state during
Power-up
• True 1/8 unit load allows up to 256 devices on the bus
• Single 3.3V supply
• High data rates. . . . . . . . . . . . . . . . . . . . . . . . . . . up to 10Mbps
• Low quiescent supply current. . . . . . . . . . . . . . . 800µA (max)
- Ultra low shutdown supply current. . . . . . . . . . . . . . . . 10nA
• -7V to +12V common mode input/output voltage range
Hot Plug circuitry ensures that the Tx and Rx outputs remain in
a high impedance state while the power supply stabilizes.
The ISL3178AE is a half duplex version. It multiplexes the Rx
inputs and Tx outputs to allow transceivers with output disable
functions in an 8 Ld package.
Related Literature
• Half duplex pinouts
• Three state Rx and Tx outputs available
• Current limiting for driver overload protection
• Pb-free (RoHS compliant)
Applications
• Automated utility meter reading systems
• AN1475, “High Temperature Behavior of ISL3178AE”
• High node count systems
• Field bus networks
• Security camera networks
• Building environmental control/ lighting systems
• Industrial/process control networks
TABLE 1. SUMMARY OF FEATURES
PART NUMBER
ISL3178AEM
October 30, 2014
FN6887.3
HALF/FULL
DUPLEX
DATA RATE
(Mbps)
SLEW-RATE
LIMITED?
HOT
PLUG?
# DEVICES
ON BUS
RX/TX
ENABLE?
QUIESCENT ICC
(µA)
LOW POWER
SHUTDOWN?
PIN
COUNT
HALF
10
NO
YES
256
YES
510
YES
8
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Copyright Intersil Americas LLC 2009, 2013, 2014. All Rights Reserved
Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.
All other trademarks mentioned are the property of their respective owners.
ISL3178AE
Ordering Information
PART NUMBER
(Notes 1, 2, 3)
TEMP. RANGE
(°C)
PART MARKING
ISL3178AEMBZ
3178A EMBZ
-55 to +125
PACKAGE
(Pb-Free)
8 Ld SOIC
PKG.
DWG. #
M8.15
NOTES:
1. Add “-T*” suffix for tape and reel. Please refer to TB347 for details on reel specifications.
2. These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach materials, and 100% matte
tin plate plus anneal (e3 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations). Intersil Pbfree products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020.
3. For Moisture Sensitivity Level (MSL), please see device information page for ISL3178AE. For more information on MSL, please see tech brief TB363
Pin Configuration
ISL3178AE
(8 LD SOIC)
TOP VIEW
RO 1
R
RE 2
DE 3
DI 4
D
8
VCC
7
B/Z
6
A/Y
5
GND
Pin Descriptions
PIN #
PIN
NAME
FUNCTION
1
RO
Receiver output: If A-B  -50mV, RO is high; If A-B  -200mV, RO is low; RO = High if A and B are unconnected (floating) or shorted.
2
RE
Receiver output enable. RO is enabled when RE is low; RO is high impedance when RE is high. If the Rx enable function isn’t
required, connect RE directly to GND or through a 1kΩ to 3kΩ resistor to GND.
3
DE
Driver output enable. The driver outputs, Y and Z, are enabled by bringing DE high, and are high impedance when DE is low. If
the Tx enable function isn’t required, connect DE to VCC through a 1kΩ to 3kΩ resistor.
4
DI
Driver input. A low on DI forces output Y low and output Z high. Similarly, a high on DI forces output Y high and output Z low.
5
GND
Ground connection.
6
A/Y
±15kV IEC61000 ESD Protected RS-485/422 level, noninverting receiver input and noninverting driver output. Pin is an input
if DE = 0; pin is an output if DE = 1.
7
B/Z
±15kV IEC61000 ESD Protected RS-485/422 level, Inverting receiver input and inverting driver output. Pin is an input if DE =
0; pin is an output if DE = 1.
8
VCC
System power supply input (3.0V to 3.6V).
Submit Document Feedback
2
FN6887.3
October 30, 2014
ISL3178AE
ISL3178AE
+3.3V
+3.3V
+
8
0.1µF
0.1µF
+
8
VCC
1 RO
VCC
R
D
2 RE
B/Z
7
3 DE
A/Y
6
4 DI
RT
RT
DI 4
7
B/Z
DE 3
6
A/Y
RE 2
R
D
GND
GND
5
5
RO 1
FIGURE 1. TYPICAL APPLICATION CIRCUIT
Truth Tables (continued)
Truth Tables
RECEIVING
TRANSMITTING
INPUTS
INPUTS
OUTPUTS
OUTPUT
RE
DE
Half Duplex
DE
Full Duplex
A-B
RO
0
0
0
X
 -0.05V
1
High-Z
High-Z
0
0
X
 -0.2V
0
High-Z *
High-Z *
0
0
X
Inputs
Open/Shorted
1
1
0
0
X
High-Z *
1
1
1
X
High-Z
RE
DE
DI
Z
Y
X
1
1
0
1
X
1
0
1
0
0
X
1
0
X
NOTE: *Shutdown Mode (see Note 12)
NOTE: *Shutdown Mode (see Note 12)
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FN6887.3
October 30, 2014
ISL3178AE
Absolute Maximum Ratings
Thermal Information
VCC to GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7V
Input Voltages
DI, DE, RE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 7V
Input/Output Voltages
A/Y, B/Z . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -8V to +13V
RO. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to (VCC +0.3V)
Short Circuit Duration
Y, Z . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Continuous
ESD Rating . . . . . . . . . . . . . . . . . . . . See “ESD PERFORMANCE” on page 5
Thermal Resistance (Typical)
JA (°C/W) JC (°C/W)
8 Ld SOIC Package (Notes 4, 5) . . . . . . . . .
120
56
Maximum Junction Temperature (Plastic Package) . . . . . . . . . . . +150°C
Maximum Storage Temperature Range . . . . . . . . . . . . . .-65°C to +150°C
Pb-Free Reflow Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see TB493
Operating Conditions
Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-55°C to +125°C
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact product
reliability and result in failures not covered by warranty.
NOTES:
4. JA is measured with the component mounted on a high effective thermal conductivity test board in free air. See Tech Brief TB379 for details.
5. For JC, the “case temp” location is taken at the package top center.
Electrical Specifications
Test Conditions: VCC = 3.0V to 3.6V; Unless Otherwise Specified. Typicals are at VCC = 3.3V, TA = +25°C,
(Note 7).
TEMP
(°C)
MIN
(Note 6)
TYP
MAX
(Note 6)
UNITS
RL = 100Ω (RS-422) (Note 2A), (Note 16)
Full
2
2.3
-
V
RL = 54Ω (RS-485) (Figure 2A)
Full
1.5
2
VCC
V
-
-
VCC
RL = 60Ω, -7V  VCM  12V (Figure 2B)
Full
1.5
2.2
-
V
VOD
RL = 54Ω or 100Ω (Figure 2A)
Full
-
0.01
0.2
V
Driver Common-mode VOUT
VOC
RL = 54Ω or 100Ω (Figure 2A)
Full
-
2
3
V
Change in Magnitude of Driver
Common-mode VOUT for
Complementary Output States
VOC
RL = 54Ω or 100Ω (Figure 2A)
Full
-
0.01
0.2
V
PARAMETER
SYMBOL
TEST CONDITIONS
DC CHARACTERISTICS
Driver Differential VOUT
VOD
No Load
Change in Magnitude of Driver
Differential VOUT for
Complementary Output States
Logic Input High Voltage
VIH
DI, DE, RE
Full
2
-
-
V
Logic Input Low Voltage
VIL
DI, DE, RE
Full
-
-
0.8
V
VHYS
DE, RE (Note 17)
25
-
100
-
mV
Logic Input Current
IIN1
DI = DE = RE = 0V or VCC (Note 18)
Full
-2
-
2
µA
Input Current (A/Y, B/Z)
IIN2
DE = 0V, VCC = 0V or
3.6V
VIN = 12V
Full
-
80
125
µA
VIN = -7V
Full
-100
-50
-
µA
DE = VCC, -7V  VY or VZ  12V (Note 9)
Full
-
-
250
mA
-7V  VCM  12V (Note 17)
Full
-200
-125
-50
mV
Logic Input Hysteresis
Driver Short-circuit Current,
VO = High or Low
IOSD1
Receiver Differential Threshold
Voltage
V TH
Receiver Input Hysteresis
V TH
VCM = 0V
25
-
15
-
mV
Receiver Output High Voltage
VOH
IO = -4mA, VID = -50mV
Full
VCC - 0.6
-
-
V
Receiver Output Low Voltage
VOL
IO = -4mA, VID = -200mV
Full
-
0.17
0.4
V
Three-state (High Impedance)
Receiver Output Current
IOZR
0.4V  VO  2.4V
Full
-1
0.015
1
µA
Receiver Input Resistance
RIN
-7V  VCM  12V
Full
96
150
-
kΩ
Receiver Short-Circuit Current
IOSR
0V  VO  VCC
Full
±7
30
±60
mA
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4
FN6887.3
October 30, 2014
ISL3178AE
Electrical Specifications
Test Conditions: VCC = 3.0V to 3.6V; Unless Otherwise Specified. Typicals are at VCC = 3.3V, TA = +25°C,
(Note 7).
PARAMETER
TEMP
(°C)
MIN
(Note 6)
TYP
MAX
(Note 6)
UNITS
DE = VCC,
RE = 0V or VCC
Full
-
510
800
µA
DE = 0V, RE = 0V
Full
-
480
700
µA
DE = 0V, RE = VCC, DI = 0V or VCC
Full
-
0.01
12
µA
IEC61000-4-2, Air-gap Discharge Method
25
-
±15
-
kV
IEC61000-4-2, Contact Discharge Method
25
-
±8
-
kV
Human Body Model, From Bus Pins to GND
25
-
±15
-
kV
HBM, per MIL-STD-883 Method 3015
25
-
±7
-
kV
Machine Model
25
-
200
-
V
SYMBOL
TEST CONDITIONS
SUPPLY CURRENT
ICC
No-load Supply Current (Note 8)
Shutdown Supply Current
ISHDN
DI = 0V or VCC
ESD PERFORMANCE
RS-485 Pins (A/Y, B/Z)
All Pins
DRIVER SWITCHING CHARACTERISTICS (ISL3178AE)
Maximum Data Rate
fMAX
VOD = ±1.5V, CD = 350pF (Figure 5) (Note 17)
Full
-
10
-
Mbps
Driver Differential Output Delay
tDD
RDIFF = 54Ω, CD = 50pF (Figure 3)
Full
-
27
40
ns
Driver Differential Output Skew
tSKEW
RDIFF = 54Ω, CD = 50pF (Figure 3)
Full
-
1
3
ns
Driver Output Skew, Part-to-Part
tDSKEW
RDIFF = 54Ω, CD = 50pF (Figure 3)
(Notes 15, 17)
Full
-
-
11
ns
tR, tF
RDIFF = 54Ω, CD = 50pF (Figure 3)
Full
-
9
15
ns
Driver Enable to Output High
tZH
RL = 500Ω, CL = 50pF, SW = GND (Figure 4),
(Note 10)
Full
-
17
50
ns
Driver Enable to Output Low
tZL
RL = 500Ω, CL = 50pF, SW = VCC (Figure 4),
(Note 10)
Full
-
16
40
ns
Driver Disable from Output High
tHZ
RL = 500Ω, CL = 50pF, SW = GND (Figure 4)
Full
-
25
40
ns
tLZ
RL = 500Ω, CL = 50pF, SW = VCC (Figure 4),
Full
-
28
50
ns
(Notes 12, 17)
Full
50
200
600
ns
Driver Differential Rise or Fall Time
Driver Disable from Output Low
Time to Shutdown
tSHDN
Driver Enable from Shutdown to
Output High
tZH(SHDN)
RL = 500Ω, CL = 50pF, SW = GND (Figure 4),
(Notes 12, 13)
Full
-
180
700
ns
Driver Enable from Shutdown to
Output Low
tZL(SHDN)
RL = 500Ω, CL = 50pF, SW = VCC (Figure 4),
(Notes 12, 13)
Full
-
90
700
ns
VID = ±1.5V (Note 17)
Full
-
10
-
Mbps
RECEIVER SWITCHING CHARACTERISTICS (ISL3178AE)
Maximum Data Rate
fMAX
Receiver Input to Output Delay
tPLH, tPHL
(Figure 6)
Full
25
33
65
ns
Receiver Skew | tPLH - tPHL |
tSKD
(Figure 6)
Full
-
1.5
10
ns
tRSKEW
(Figure 6), (Notes 15, 17)
Full
-
-
15
ns
Receiver Enable to Output High
tZH
RL = 1kΩ, CL = 15pF, SW = GND (Figure 7),
(Note 11)
Full
5
11
17
ns
Receiver Enable to Output Low
tZL
RL = 1kΩ, CL = 15pF, SW = VCC (Figure 7),
(Note 11)
Full
5
11
17
ns
Receiver Disable from Output High
tHZ
RL = 1kΩ, CL = 15pF, SW = GND (Figure 7),
Full
4
7
15
ns
tLZ
RL = 1kΩ, CL = 15pF, SW = VCC (Figure 7),
Full
4
7
15
ns
(Notes 12, 17)
Full
50
180
600
ns
Receiver Skew, Part-to-Part
Receiver Disable from Output Low
Time to Shutdown
Submit Document Feedback
tSHDN
5
FN6887.3
October 30, 2014
ISL3178AE
Electrical Specifications
Test Conditions: VCC = 3.0V to 3.6V; Unless Otherwise Specified. Typicals are at VCC = 3.3V, TA = +25°C,
(Note 7).
PARAMETER
SYMBOL
Receiver Enable from Shutdown to
Output High
tZH(SHDN)
Receiver Enable from Shutdown to
Output Low
tZL(SHDN)
TEMP
(°C)
MIN
(Note 6)
TYP
MAX
(Note 6)
UNITS
RL = 1kΩ, CL = 15pF, SW = GND (Figure 7),
(Notes 12, 14)
Full
-
240
500
ns
RL = 1kΩ, CL = 15pF, SW = VCC (Figure 7),
(Notes 12, 14)
Full
-
240
500
ns
TEST CONDITIONS
NOTES:
6. Parameters with MIN and/or MAX limits are 100% tested at +25°C, unless otherwise specified. Temperature limits established by characterization
and are not production tested.
7. All currents into device pins are positive; all currents out of device pins are negative. All voltages are referenced to device ground unless otherwise
specified.
8. Supply current specification is valid for loaded drivers when DE = 0V.
9. Applies to peak current. See “Typical Performance Curves” starting on page 10 for more information.
10. When testing devices with the shutdown feature, keep RE = 0 to prevent the device from entering SHDN.
11. When testing devices with the shutdown feature, the RE signal high time must be short enough (typically <100ns) to prevent the device from entering
SHDN.
12. Versions with a shutdown feature are put into shutdown by bringing RE high and DE low. If the inputs are in this state for less than 50ns, the parts
are guaranteed not to enter shutdown. If the inputs are in this state for at least 600ns, the parts are guaranteed to have entered shutdown. See “Low
Power Shutdown Mode” on page 10.
13. Keep RE = VCC, and set the DE signal low time >600ns to ensure that the device enters SHDN.
14. Set the RE signal high time >600ns to ensure that the device enters SHDN.
15. tSKEW is the magnitude of the difference in propagation delays of the specified terminals of two units tested with identical test conditions (VCC,
temperature, etc.).
16. VCC 3.15V
17. Limits established by characterization and are not production tested.
18. If the Tx or Rx enable function isn’t needed, connect the enable pin to the appropriate supply (see “Pin Descriptions” on page 2) through a 1kΩ to
3kΩ resistor.
Test Circuits and Waveforms
VCC
RL/2
DE
DI
VCC
Z
Z
DI
VOD
D
375Ω
DE
VOD
D
Y
Y
RL/2
FIGURE 2A. VOD AND VOC
VOC
RL = 60Ω
VCM
-7V TO +12V
375Ω
FIGURE 2B. VOD WITH COMMON MODE LOAD
FIGURE 2. DC DRIVER TEST CIRCUITS
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ISL3178AE
Test Circuits and Waveforms (Continued)
3V
DI
1.5V
1.5V
0V
tPHL
tPLH
DE
VCC
Z
DI
RDIFF
D
OUT (Z)
VOH
OUT (Y)
VOL
CD
Y
SIGNAL
GENERATOR
90%
DIFF OUT (Y to Z)
+VOD
90%
10%
10%
tR
-VOD
tF
SKEW = |tPLH - tPHL|
FIGURE 3A. TEST CIRCUIT
FIGURE 3B. MEASUREMENT POINTS
FIGURE 3. DRIVER PROPAGATION DELAY AND DIFFERENTIAL TRANSITION TIMES
DE
Z
DI
500Ω
VCC
D
SIGNAL
GENERATOR
SW
Y
GND
50pF
3V
DE
Note 12
1.5V
1.5V
0V
tZH, tZH(SHDN)
OUTPUT HIGH
Note 12
PARAMETER
OUTPUT
RE
DI
SW
tHZ
Y/Z
X
1/0
GND
tLZ
Y/Z
X
0/1
VCC
tZH
Y/Z
0 (Note 10)
1/0
GND
tZL
Y/Z
0 (Note 10)
0/1
VCC
tZH(SHDN)
Y/Z
1 (Note 13)
1/0
GND
tZL(SHDN)
Y/Z
1 (Note 13)
0/1
VCC
tHZ
VOH - 0.25V
50%
OUT (Y, Z)
VOH
0V
tZL, tZL(SHDN)
Note 12
tLZ
VCC
OUT (Y, Z)
50%
OUTPUT LOW
FIGURE 4A. TEST CIRCUIT
VOL + 0.25V V
OL
FIGURE 4B. MEASUREMENT POINTS
FIGURE 4. DRIVER ENABLE AND DISABLE TIMES
VCC
3V
DE
+
Z
DI
54Ω
D
Y
CD
DI
0V
VOD
-
SIGNAL
GENERATOR
+VOD
DIFF OUT (Y to Z)
-VOD
0V
FIGURE 5B. MEASUREMENT POINTS
FIGURE 5A. TEST CIRCUIT
FIGURE 5. DRIVER DATA RATE
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October 30, 2014
ISL3178AE
Test Circuits and Waveforms (Continued)
+1.5V
RE
GND
A
15pF
B
R
A
0V
0V
RO
-1.5V
tPLH
tPHL
VCC
SIGNAL
GENERATOR
1.5V
RO
1.5V
0V
FIGURE 6B. MEASUREMENT POINTS
FIGURE 6A. TEST CIRCUIT
FIGURE 6. RECEIVER PROPAGATION DELAY
RE
GND
B
A
R
Note 12
1kΩ
RO
VCC
SW
SIGNAL
GENERATOR
GND
3V
RE
1.5V
1.5V
15pF
0V
tZH, tZH(SHDN)
Note 12
PARAMETER
DE
A
SW
tHZ
X
+1.5V
GND
tLZ
X
-1.5V
VCC
tZH (Note 11)
0
+1.5V
GND
tZL (Note 11)
0
-1.5V
VCC
tZH(SHDN) (Note 14)
0
+1.5V
GND
tZL(SHDN) (Note 14)
0
-1.5V
VCC
FIGURE 7A. TEST CIRCUIT
OUTPUT HIGH
tHZ
V
VOH - 0.25V OH
1.5V
RO
0V
tZL, tZL(SHDN)
Note 12
RO
tLZ
VCC
1.5V
VOL + 0.25V V
OUTPUT LOW
OL
FIGURE 7B. MEASUREMENT POINTS
FIGURE 7. RECEIVER ENABLE AND DISABLE TIMES
Application Information
RS-485 and RS-422 are differential (balanced) data transmission
standards for use in long haul or noisy environments. RS-422 is a
subset of RS-485, so RS-485 transceivers are also RS-422
compliant. RS-422 is a point-to-multipoint (multidrop) standard,
which allows only one driver and up to 10 (assuming one unit load
devices) receivers on each bus. RS-485 is a true multipoint
standard, which allows up to 32 one-unit load devices
(any combination of drivers and receivers) on each bus. To allow for
multipoint operation, the RS-485 spec requires that drivers must
handle bus contention without sustaining any damage.
Another important advantage of RS-485 is the extended
common mode range (CMR), which specifies that the driver
outputs and receiver inputs withstand signals that range from
+12V to -7V. RS-422 and RS-485 are intended for long runs, thus
the wide CMR is necessary to handle ground potential
differences, as well as voltages induced in the cable by external
fields.
Receiver Features
Receiver input resistance of 96kΩ surpasses the RS-422 spec of
4kΩ and is eight times the RS-485 “Unit Load (UL)” requirement
of 12kΩ minimum. Thus, these products are known as “oneeighth UL” transceivers and there can be up to 256 of these
devices on a network while still complying with the RS-485
loading specification.
Receiver inputs function with common mode voltages as great as
+9V/-7V outside the power supplies (i.e., +12V and -7V), making
them ideal for long networks where induced voltages and ground
potential differences are realistic concerns.
All the receivers include a “Full Fail-Safe” function that
guarantees a high level receiver output if the receiver inputs are
unconnected (floating) or shorted. Fail-safe with shorted inputs is
achieved by setting the Rx upper switching point to -50mV,
thereby ensuring that the Rx sees 0V differential as a high input
level.
Receivers easily meet the data rates supported by the
corresponding driver, and all receiver outputs are tri-statable via
the active low RE input.
This device utilizes a differential input receiver for maximum noise
immunity and common mode rejection. The Input sensitivity is
better than ±200mV, as required by the RS-422 and RS-485
specifications.
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ISL3178AE
Driver Features
AIR-GAP DISCHARGE TEST METHOD
The RS-485/422 driver is a differential output device that
delivers at least 1.5V across a 54Ω load (RS-485) and at least 2V
across a 100Ω load (RS-422). The drivers feature low
propagation delay skew to maximize bit width and to minimize
EMI.
For this test method, a charged probe tip moves toward the IC pin
until the voltage arcs to it. The current waveform delivered to the
IC pin depends on approach speed, humidity, temperature, etc.
so it is difficult to obtain repeatable results. The ISL3178AE
RS-485 pins withstand ±15kV air-gap discharges.
The drivers is tri-statable via the active high DE input. Outputs of
the ISL3178AE drivers are not limited, so faster output transition
times allow data rates of at least 10Mbps.
CONTACT DISCHARGE TEST METHOD
Hot Plug Function
When a piece of equipment powers up, there is a period of time
where the processor or ASIC driving the RS-485 control lines (DE,
RE) is unable to ensure that the RS-485 Tx and Rx outputs are
kept disabled. If the equipment is connected to the bus, a driver
activating prematurely during power-up may crash the bus. To
avoid this scenario, the ISL3178AE versions with output enable
pins incorporate a “Hot Plug” function. During power-up, circuitry
monitoring VCC ensures that the Tx and Rx outputs remain disabled
for a period of time, regardless of the state of DE and RE. This gives
the processor/ASIC a chance to stabilize and drive the RS-485
control lines to the proper states.
ESD Protection
All pins on this device includes class 3 (>7kV) Human Body
Model (HBM) ESD protection structures, but the RS-485 pins
(driver outputs and receiver inputs) incorporate advanced
structures allowing them to survive ESD events in excess of
±15kV HBM and ±15kV IEC61000. The RS-485 pins are
particularly vulnerable to ESD damage because they typically
connect to an exposed port on the exterior of the finished
product. Simply touching the port pins, or connecting a cable,
can cause an ESD event that might destroy unprotected ICs.
These new ESD structures protect the device whether or not it is
powered up, and without degrading the RS-485 common mode
range of -7V to +12V. This built-in ESD protection eliminates the
need for board level protection structures (e.g., transient
suppression diodes), and the associated, undesirable capacitive
load they present.
IEC61000-4-2 Testing
The IEC61000 test method applies to finished equipment, rather
than to an individual IC. Therefore, the pins most likely to suffer
an ESD event are those that are exposed to the outside world (the
RS-485 pins in this case), and the IC is tested in its typical
application configuration (power applied) rather than testing
each pin-to-pin combination. The lower current limiting resistor
coupled with the larger charge storage capacitor yields a test
that is much more severe than the HBM test. The extra ESD
protection built into this device’s RS-485 pins allows the design
of equipment meeting level 4 criteria without the need for
additional board level protection on the RS-485 port.
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During the contact discharge test, the probe contacts the tested
pin before the probe tip is energized, thereby eliminating the
variables associated with the air-gap discharge. The result is a
more repeatable and predictable test, but equipment limits
prevent testing devices at voltages higher than ±8kV. The
ISL3178AE survives ±8kV contact discharges on the RS-485
pins.
Data Rate, Cables, and Terminations
The RS-485/422 are intended for network lengths up to 4000,
but the maximum system data rate decreases as the
transmission length increases. The device operates at 10Mbps
are limited to lengths less than 100.
Twisted pair is the cable of choice for RS-485/422 networks.
Twisted pair cables tend to pick up noise and other
electromagnetically induced voltages as common mode signals,
which are effectively rejected by the differential receivers in
these ICs.
Proper termination is imperative to minimize reflections. Short
networks using the 250kbps versions need not be terminated,
but, terminations are recommended unless power dissipation is
an overriding concern.
In point-to-point, or point-to-multipoint (single driver on bus)
networks, the main cable should be terminated in its
characteristic impedance (typically 120Ω) at the end farthest
from the driver. In multireceiver applications, stubs connecting
receiver to the main cable should be kept as short as possible.
Multipoint (multidriver) systems require that the main cable be
terminated in its characteristic impedance at both ends. Stubs
connecting a transceiver to the main cable should be kept as
short as possible.
Built-In Driver Overload Protection
As stated previously, the RS-485 spec requires that drivers
survive worst case bus contentions undamaged. These devices
meet this requirement via driver output short circuit current limit
circuitry.
The driver output stages incorporate short circuit current limiting
circuitry, which ensures that the output current never exceeds the
RS-485 spec, even at the common mode voltage range
extremes. Additionally, these devices utilize a foldback circuit
which reduces the short circuit current, and thus the power
dissipation, whenever the contending voltage exceeds either
supply.
FN6887.3
October 30, 2014
ISL3178AE
Low Power Shutdown Mode
This CMOS transceiver all uses a fraction of the power required
by its bipolar counterparts, but it also includes a shutdown
feature that reduces the already low quiescent ICC to a 10nA
trickle. This device enters shutdown whenever the receiver and
driver are simultaneously disabled (RE = VCC and DE = GND) for a
period of at least 600ns. Disabling both the driver and the
Typical Performance Curves
receiver for less than 50ns guarantees that the transceiver will
not enter shutdown.
Note that receiver and driver enable times increase when the
transceiver enables from shutdown. Refer to Notes 10 through 14,
at the end of the “Electrical Specification table” on page 6, for more
information.
VCC = 3.3V, TA = +25°C; Unless Otherwise Specified.
DIFFERENTIAL OUTPUT VOLTAGE (V)
DRIVER OUTPUT CURRENT (mA)
120
100
80
60
40
20
0
0
0.5
1.0
1.5
2.0
2.5
3.0
DIFFERENTIAL OUTPUT VOLTAGE (V)
2.9
2.7
2.5
2.3
RDIFF = 120Ω
2.1
1.9
RDIFF = 54Ω
1.7
1.5
-60
3.5
-40
-20
0
20
40
60
TEMPERATURE (°C)
80
100
120
FIGURE 9. DRIVER DIFFERENTIAL OUTPUT VOLTAGE vs
TEMPERATURE
FIGURE 8. DRIVER OUTPUT CURRENT vs DIFFERENTIAL OUTPUT
VOLTAGE
600
200
550
Y OR Z = LOW
ICC DE-VCC
100
500
50
ICC (µA)
OUTPUT CURRENT (mA)
150
0
450
-50
ICC DE-GND
Y OR Z = HIGH
400
-100
-150
-7 -6
-4
-2
0
2
4
6
OUTPUT VOLTAGE (V)
8
10
FIGURE 10. DRIVER OUTPUT CURRENT vs SHORT CIRCUIT
VOLTAGE
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10
12
350
-60
-40
-20
0
20
40
60
TEMPERATURE (°C)
80
100
120
FIGURE 11. SUPPLY CURRENT vs TEMPERATURE
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ISL3178AE
Typical Performance Curves
VCC = 3.3V, TA = +25°C; Unless Otherwise Specified. (Continued)
1.6
40
PROPAGATION DELAY (ns)
35
TPHL
1.5
TPLH
1.4
30
SKEW (ns)
25
20
15
1.3
1.2
10
1.1
5
0
15
30
45
60
75
1
-60 -45 -30 -15
90 105 120
TEMPERATURE (°C)
0
5
RO
0
RECEIVER OUTPUT (V)
5
DRIVER INPUT (V)
3.0
2.5
DRIVER OUTPUT (V)
RECEIVER OUTPUT (V)
DRIVER OUTPUT (V)
DI
B/Z
2.0
1.5
1.0
15 30 45 60
TEMPERATURE (°C)
75
90 105 120
FIGURE 13. DRIVER DIFFERENTIAL SKEW vs TEMPERATURE
FIGURE 12. DRIVER DIFFERENTIAL PROPAGATION DELAY vs
TEMPERATURE)
RDIFF = 54Ω, CD = 50pF
0
A/Y
0.5
0
RDIFF = 54Ω, CD = 50pF
DI
5
0
5
RO
0
DRIVER INPUT (V)
0
-60 -45 -30 -15
3.0
2.5
A/Y
2.0
1.5
B/Z
1.0
0.5
0
TIME (10ns/DIV)
TIME (10ns/DIV)
FIGURE 15. DRIVER AND RECEIVER WAVEFORMS,
HIGH-TO-LOW
FIGURE 14. DRIVER AND RECEIVER WAVEFORMS,
LOW-TO-HIGH
RECEIVER OUTPUT CURRENT (mA)
35
VOL, +25°C
30
25
VOL, +85°C
VOH, +25°C
20
15
VOH, +85°C
10
5
0
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
RECEIVER OUTPUT VOLTAGE (V)
FIGURE 16. RECEIVER OUTPUT CURRENT vs RECEIVER OUTPUT VOLTAGE
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ISL3178AE
Die Characteristics
Additional Information
DIE DIMENSIONS
WORST CASE CURRENT DENSITY
Thickness: 14 mils
1295µm x 1350µm
N/A
PROCESS
Interface Materials
Si GateBiCMOS
TRANSISTOR COUNT
GLASSIVATION
Sandwich TEOS & Nitride
535
PAD OPENING SIZE
TOP METALLIZATION:
90µm x 90µm
Type: Al with 0.5% Cu
Thickness: 28kA
WAFER SIZE
SUBSTRATE
200mm (~8 inch)
N/A
TRANSISTOR COUNT
BACKSIDE FINISH
535
Silicon/Polysilicon/Oxide
Assembly Related Information
SUBSTRATE POTENTIAL
GND (powered up)
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ISL3178AE
Revision History
The revision history provided is for informational purposes only and is believed to be accurate, but not warranted. Please go to the web to make sure that
you have the latest revision.
DATE
REVISION
October 30, 2014
FN6887.3
CHANGE
Applied Intersil’s new datasheet template.
On page 1:
Changed “+125mA/-100mA” to “+125µA/-100µA”.
Added AN1475, “High Temperature Behavior of ISL3178AE”.
In Features" section, 3rd bullet, removed "(only versions . . .)"
Remove 2nd entry in Table 1.
On page 2, removed ISL3178AEMW from the Ordering Information table.
On page 6, removed Note 19.
On page 12, removed Table 2.
Added revision history and About Intersil verbiage.
About Intersil
Intersil Corporation is a leading provider of innovative power management and precision analog solutions. The company's products
address some of the largest markets within the industrial and infrastructure, mobile computing and high-end consumer markets.
For the most updated datasheet, application notes, related documentation and related parts, please see the respective product
information page found at www.intersil.com.
You may report errors or suggestions for improving this datasheet by visiting www.intersil.com/ask.
Reliability reports are also available from our website at www.intersil.com/support
For additional products, see www.intersil.com/en/products.html
Intersil products are manufactured, assembled and tested utilizing ISO9001 quality systems as noted
in the quality certifications found at www.intersil.com/en/support/qualandreliability.html
Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time
without notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be
accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third
parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.
For information regarding Intersil Corporation and its products, see www.intersil.com
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ISL3178AE
Package Outline Drawing
M8.15
8 LEAD NARROW BODY SMALL OUTLINE PLASTIC PACKAGE
Rev 4, 1/12
DETAIL "A"
1.27 (0.050)
0.40 (0.016)
INDEX
6.20 (0.244)
5.80 (0.228)
AREA
0.50 (0.20)
x 45°
0.25 (0.01)
4.00 (0.157)
3.80 (0.150)
1
2
8°
0°
3
0.25 (0.010)
0.19 (0.008)
SIDE VIEW “B”
TOP VIEW
2.20 (0.087)
SEATING PLANE
5.00 (0.197)
4.80 (0.189)
1.75 (0.069)
1.35 (0.053)
1
8
2
7
0.60 (0.023)
1.27 (0.050)
3
6
4
5
-C-
1.27 (0.050)
0.51(0.020)
0.33(0.013)
SIDE VIEW “A
0.25(0.010)
0.10(0.004)
5.20(0.205)
TYPICAL RECOMMENDED LAND PATTERN
NOTES:
1. Dimensioning and tolerancing per ANSI Y14.5M-1994.
2. Package length does not include mold flash, protrusions or gate burrs.
Mold flash, protrusion and gate burrs shall not exceed 0.15mm (0.006
inch) per side.
3. Package width does not include interlead flash or protrusions. Interlead
flash and protrusions shall not exceed 0.25mm (0.010 inch) per side.
4. The chamfer on the body is optional. If it is not present, a visual index
feature must be located within the crosshatched area.
5. Terminal numbers are shown for reference only.
6. The lead width as measured 0.36mm (0.014 inch) or greater above the
seating plane, shall not exceed a maximum value of 0.61mm (0.024 inch).
7. Controlling dimension: MILLIMETER. Converted inch dimensions are not
necessarily exact.
8. This outline conforms to JEDEC publication MS-012-AA ISSUE C.
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