DATASHEET
ISL32470E, ISL32472E, ISL32475E, ISL32478E
FN7784
Rev 2.00
Feb 14, 2019
Fault Protected, Extended Common-Mode Range, RS-485/RS-422 Transceivers
with ±16.5kV ESD
The ISL32470E, ISL32472E, ISL32475E, and ISL32478E are
fault-protected, extended common-mode range differential
transceivers that exceed the RS-485 and RS-422 standards for
balanced communication. The RS-485 bus pins (driver outputs
and receiver inputs) are fault protected against overvoltages
up to ±60V and are protected against ±16.5kV ESD strikes
without latch-up. Additionally, these transceivers operate in
environments with common-mode voltages up to ±15V
(exceeds the RS-485 requirement), making this fault-protected
RS-485 family one of the most robust on the market.
Features
The transmitters (Tx) deliver an exceptional 2.5V (typical)
differential output voltage into the RS-485 specified 54Ω load.
This yields better noise immunity than standard RS-485 ICs or
allows up to six 120Ω terminations in star topologies.
• High Rx IOL for opto-couplers in isolated designs
The receiver (Rx) inputs feature a full fail-safe design that
ensures a logic high Rx output if the Rx inputs are floating,
shorted, or on a terminated but undriven (idle) bus. The Rx
outputs feature high drive levels; typically, 15mA at VOL = 1V
(to ease the design of opto-coupled isolated interfaces).
Half duplex (Rx inputs and Tx outputs multiplexed together)
and full duplex pinouts are available. See Table 1 on page 2 for
key features and configurations by device number.
For a fault-protected RS-485 transceiver with a ±25V extended
common-mode range, see the ISL32490E and ISL32483E
datasheets.
Related Literature
• Fault protected RS-485 bus pins . . . . . . . . . . . . . . Up to ±60V
• Extended common-mode range. . . . . . . . . . . . . . . . . . . . ±15V
larger than required for RS-485
• 1/4 unit load for up to 128 devices on the bus
• ±16.5kV HBM ESD protection on RS-485 bus pins
• High transient over-voltage tolerance . . . . . . . . . . . . . . . ±80V
• Full fail-safe (open, short, terminated) RS-485 receivers
• Hot plug circuitry: Tx and Rx outputs remain three-state
during power-up/power-down
• RS-485 data rates. . . . . . . . . . . . . . . . . . . . . .250kbps to 15Mbps
• Low quiescent supply current. . . . . . . . . . . . . . . . . . . . 2.3mA
• Ultra low shutdown supply current. . . . . . . . . . . . . . . . . . 10µA
Applications
• Utility meters and automated meter reading systems
• High node count RS-485 systems
• PROFIBUS and RS-485 based field bus networks, factory
automation
• Security camera networks
• Building lighting and environmental control systems
• Industrial/process control networks
For a full list of related documents, visit our website:
• ISL32470E, ISL32472E, ISL32475E, and ISL32478E device
pages
20
15
VID = ±1V
B
12
COMMON-MODE RANGE
15
VOLTAGE (V)
A
10
5
0
RO
0
-7
-15
-5
TIME (20ns/DIV)
FIGURE 1. EXCEPTIONAL Rx OPERATES AT >15Mbps EVEN WITH
±15V COMMON-MODE VOLTAGE
FN7784 Rev 2.00
Feb 14, 2019
STANDARD RS-485
TRANSCEIVER
ISL3247xE
FIGURE 2. TRANSCEIVERS DELIVER SUPERIOR COMMON-MODE
RANGE vs STANDARD RS-485 DEVICES
Page 1 of 21
ISL32470E, ISL32472E, ISL32475E, ISL32478E
TABLE 1. SUMMARY OF FEATURES
HALF/FULL
DUPLEX
DATA RATE
(Mbps)
SLEW-RATE
LIMITED?
EN PINS?
HOT
PLUG?
QUIESCENT ICC
(mA)
LOW POWER
SHUTDOWN?
PIN COUNT
ISL32470E
Full
0.25
Yes
Yes
Yes
2.3
Yes
14
ISL32472E
Half
0.25
Yes
Yes
Yes
2.3
Yes
8
ISL32475E
Half
1
Yes
Yes
Yes
2.3
Yes
8
ISL32478E
Half
15
No
Yes
Yes
2.3
Yes
8
PART NUMBER
Typical Operating Circuits
+5V
+5V
+
13, 14
VCC
2 RO
R
0.1µF
0.1µF
+
13, 14
9 Y VCC
RT
A 12
10 Z
B 11
D
DI 5
3 RE
DE 4
4 DE
RE 3
5 DI
RT
Z 10
11 B
Y 9
D
GND
RO 2
R
12 A
GND
6, 7
6, 7
FIGURE 3. ISL32470E FULL DUPLEX EXAMPLE
+5V
+5V
+
8
0.1µF
0.1µF
+
8
VCC
1 RO
R
D
2 RE
B/Z
A/Y
3 DE
4 DI
VCC
7
6
RT
RT
DI 4
7
B/Z
DE 3
6
A/Y
RE 2
R
D
GND
GND
5
5
RO 1
FIGURE 4. ISL32472E, ISL32475E, ISL32478E HALF DUPLEX EXAMPLE
FN7784 Rev 2.00
Feb 14, 2019
Page 2 of 21
ISL32470E, ISL32472E, ISL32475E, ISL32478E
Ordering Information
PART NUMBER
(Notes 2, 3)
PART
MARKING
TEMP. RANGE
(°C)
TAPE AND REEL
(Units) (Note 1)
PACKAGE
(RoHS Compliant)
PKG.
DWG. #
ISL32470EIBZ
ISL32470 EIBZ
-40 to +85
-
14 Ld SOIC
M14.15
ISL32470EIBZ -T
ISL32470 EIBZ
-40 to +85
2.5k
14 Ld SOIC
M14.15
ISL32470EIBZ -T7A
ISL32470 EIBZ
-40 to +85
250
14 Ld SOIC
M14.15
ISL32472EIBZ
32472 EIBZ
-40 to +85
-
8 Ld SOIC
M8.15
ISL32472EIBZ -T
32472 EIBZ
-40 to +85
2.5k
8 Ld SOIC
M8.15
ISL32472EIBZ-T7A
32472 EIBZ
-40 to +85
250
8 Ld SOIC
M8.15
ISL32475EIBZ
32475 EIBZ
-40 to +85
-
8 Ld SOIC
M8.15
ISL32475EIBZ-T
32475 EIBZ
-40 to +85
2.5k
8 Ld SOIC
M8.15
ISL32475EIBZ-T7A
32475 EIBZ
-40 to +85
250
8 Ld SOIC
M8.15
ISL32478EIBZ
32478 EIBZ
-40 to +85
-
8 Ld SOIC
M8.15
ISL32478EIBZ-T
32478 EIBZ
-40 to +85
2.5k
8 Ld SOIC
M8.15
ISL32478EIBZ-T7A
32478 EIBZ
-40 to +85
250
8 Ld SOIC
M8.15
NOTES:
1. See TB347 for details about reel specifications.
2. These 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).Pb-free 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), see the ISL32470E, ISL32472E, ISL32475E, ISL32478E device pages. For more information about MSL, see TB363.
Pin Configurations
ISL32470E
(14 LD SOIC)
TOP VIEW
ISL32472E, ISL32475E, ISL32478E
(8 LD SOIC)
TOP VIEW
8
VCC
NC 1
2
7
B/Z
RO 2
DE
3
6
A/Y
RE 3
12 A
DI
4
5
GND
DE 4
11 B
RO
1
RE
R
D
DI 5
FN7784 Rev 2.00
Feb 14, 2019
14 VCC
R
D
13 NC
10 Z
GND 6
9 Y
GND 7
8 NC
Page 3 of 21
ISL32470E, ISL32472E, ISL32475E, ISL32478E
Pin Descriptions
PIN
NAME
8 LD
PIN #
14 LD
PIN #
RO
1
2
Receiver output. If A-B ≥ 10mV, RO is high; if A-B ≤ 200mV, RO is low; RO = high if A and B are unconnected (floating),
shorted together, or connected to an undriven, terminated bus.
RE
2
3
Receiver output enable. RO is enabled when RE is low; RO is high impedance when RE is high. Internally pulled low.
DE
3
4
Driver output enable. The driver outputs, Y and Z, are enabled by bringing DE high. They are high impedance when DE is
low. Internally pulled high.
DI
4
5
Driver input. A low on DI forces output Y low and output Z high. A high on DI forces output Y high and output Z low.
GND
5
6, 7
A/Y
6
-
±60V fault and ±16.5kV HBM ESD protected, RS-485/RS-422 level, non-inverting receiver input and non-inverting driver
output. Pin is an input if DE = 0; pin is an output if DE = 1.
B/Z
7
-
±60V fault and ±16.5kV HBM ESD protected, RS-485/RS-422 level, inverting receiver input and inverting driver output.
Pin is an input if DE = 0; pin is an output if DE = 1.
A
-
12
±60V fault and ±15kV HBM ESD protected, RS-485/RS-422 level, non-inverting receiver input.
B
-
11
±60V fault and ±15kV HBM ESD protected, RS-485/RS-422 level, inverting receiver input.
Y
-
9
±60V fault and ±15kV HBM ESD protected, RS-485/RS-422 level, non-inverting driver output.
Z
-
10
±60V fault and ±15kV HBM ESD protected, RS-485/RS-422 level, inverting driver output.
VCC
8
14
System power supply input (4.5V to 5.5V).
NC
-
1, 8, 13
FUNCTION
Ground connection.
No internal connection.
Truth Tables
TRANSMITTING
RECEIVING
INPUTS
OUTPUTS
INPUTS
RE
DE
DI
Z
Y
X
1
1
0
1
X
1
0
1
0
0
0
X
High-Z
High-Z
1
0
X
High-Z
(Note 4)
High-Z
(Note 4)
NOTE:
4. Low Power Shutdown Mode (see Note 13 on page 9).
OUTPUT
RE
DE
Half Duplex
DE
Full Duplex
A-B
RO
0
0
X
≥ -0.01V
1
0
0
X
≤ -0.2V
0
0
0
X
Inputs
Open/Shorted
1
1
0
0
X
High-Z
(see Note 5)
1
1
1
X
High-Z
NOTE:
5. Low Power Shutdown Mode (see Note 13 on page 9).
FN7784 Rev 2.00
Feb 14, 2019
Page 4 of 21
ISL32470E, ISL32472E, ISL32475E, ISL32478E
Absolute Maximum Ratings
Thermal Information
VCC to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7V
Input Voltages
DI, DE, RE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to (VCC + 0.3V)
Input/Output Voltages
A/Y, B/Z, A, B, Y, Z . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±60V
A/Y, B/Z, A, B, Y, Z
(Transient Pulse Through 100Ω, Note 17). . . . . . . . . . . . . . . . . . . ±80V
RO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to (VCC +0.3V)
Short-Circuit Duration
Y, Z . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Indefinite
ESD Rating . . . . . . . . . . . . . . . . . . . . see “ESD PERFORMANCE” on page 6
Latch-Up (per JESD78, Level 2, Class A) . . . . . . . . . . . . . . . . . . . . . +125°C
Thermal Resistance (Typical)
θJA (°C/W) θJC (°C/W)
8 Ld SOIC Package (Notes 6, 7) . . . . . . . . . .
108
47
14 Ld SOIC Package (Notes 6, 7) . . . . . . . . .
88
39
Maximum Junction Temperature (Plastic Package). . . . . . . . . . . . . . . . +150°C
Maximum Storage Temperature Range . . . . . . . . . . . . . .-65°C to +150°C
Pb-Free Reflow Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see TB493
Recommended Operating Conditions
Supply Voltage (VCC). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5V
Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40°C to +85°C
Bus Pin Common-Mode Voltage Range. . . . . . . . . . . . . . . . . . -15V to +15V
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions can adversely impact product
reliability and result in failures not covered by warranty.
NOTES:
6. θJA is measured with the component mounted on a high-effective thermal conductivity test board in free air. See TB379 for details.
7. For θJC, the “case temp” location is taken at the package top center.
Electrical Specifications Test Conditions: VCC = 4.5V to 5.5V; unless otherwise specified. Typical values are VCC = 5V, TA = +25°C
(Note 8). Boldface limits apply over the operating temperature range, -40°C to +85°C.
PARAMETER
TEMP
(°C)
MIN
(Note 16)
TYP
MAX
(Note 16)
UNIT
Full
-
-
VCC
V
RL = 100Ω (RS-422)
Full
2.4
3.2
-
V
RL = 54Ω (RS-485)
Full
1.5
2.5
VCC
V
RL = 54Ω (PROFIBUS, VCC ≥ 5V)
Full
2.0
2.5
-
V
RL = 21Ω (six 120Ω terminations for star
configurations, VCC ≥ 4.75V)
Full
0.8
1.3
-
V
SYMBOL
TEST CONDITIONS
DC CHARACTERISTICS
Driver Differential VOUT (No load)
VOD1
Driver Differential VOUT (Loaded,
Figure 5A)
VOD2
Change in Magnitude of Driver
Differential VOUT for
Complementary Output States
ΔVOD
RL = 54Ω or 100Ω (Figure 5A)
Full
-
-
0.2
V
Driver Differential VOUT with
Common-Mode Load (Figure 5B)
VOD3
RL = 60Ω, -7V ≤ VCM ≤ 12V
Full
1.5
2.1
VCC
V
RL = 60Ω, -15V ≤ VCM ≤ 15V (VCC ≥ 4.75V)
Full
1.7
2.3
-
V
Driver Common-Mode VOUT
(Figure 5A)
VOC
RL = 54Ω or 100Ω
Full
-1
-
3
V
Change in Magnitude of Driver
Common-Mode VOUT for
Complementary Output States
ΔVOC
RL = 54Ω or 100Ω (Figure 5A)
Full
-
-
0.2
V
Driver Short-Circuit Current
IOSD
DE = VCC, -15V ≤ VO ≤ 15V (Note 10)
Full
-250
-
250
mA
IOSD1
At first foldback, 22V ≤ VO ≤ -22V
Full
-83
-
83
mA
IOSD2
At second foldback, 35V ≤ VO ≤ -35V
Full
-13
-
13
mA
Logic Input High Voltage
VIH
DE, DI, RE
Full
2.5
-
-
V
Logic Input Low Voltage
VIL
DE, DI, RE
Full
-
-
0.8
V
Logic Input Current
IIN1
DI
Full
-1
-
1
µA
DE, RE
Full
-15
6
15
µA
FN7784 Rev 2.00
Feb 14, 2019
Page 5 of 21
ISL32470E, ISL32472E, ISL32475E, ISL32478E
Electrical Specifications Test Conditions: VCC = 4.5V to 5.5V; unless otherwise specified. Typical values are VCC = 5V, TA = +25°C
(Note 8). Boldface limits apply over the operating temperature range, -40°C to +85°C. (Continued)
PARAMETER
Input/Output Current (A/Y, B/Z)
Input Current (A, B)
(Full Duplex Versions Only)
Output Leakage Current (Y, Z)
(Full Duplex Versions Only)
SYMBOL
IIN2
IIN3
IOZD
TEMP
(°C)
MIN
(Note 16)
TYP
MAX
(Note 16)
UNIT
Full
-
110
250
µA
Full
-200
-75
-
µA
VIN = ±15V
Full
-800
±240
800
µA
VIN = ±60V
(Note 18)
Full
-6
±0.5
6
mA
VIN = 12V
Full
-
90
125
µA
VIN = -7V
Full
-100
-70
-
µA
VIN = ±15V
Full
-500
±200
500
µA
VIN = ±60V
(Note 18)
Full
-3
±0.4
3
mA
VIN = 12V
Full
-
20
200
µA
VIN = -7V
Full
-100
-5
-
µA
VIN = ±15V
Full
-500
±40
500
µA
VIN = ±60V
(Note 18)
Full
-3
±0.1
3
mA
TEST CONDITIONS
DE = 0V, VCC = 0V or VIN = 12V
5.5V
VIN = -7V
VCC = 0V or 5.5V
RE = 0V, DE = 0V,
VCC = 0V or 5.5V
Receiver Differential Threshold
Voltage
V TH
-15V ≤ VCM ≤ 15V
Full
-200
-100
-10
mV
Receiver Input Hysteresis
ΔV TH
-15V ≤ VCM ≤ 15V
25
-
25
-
mV
Receiver Output High Voltage
VOH
IO = -2mA, VID = -10mV
Full
VCC - 0.5
4.75
-
V
IO = -8mA, VID = -10mV
Full
2.8
4.2
-
V
Receiver Output Low Voltage
VOL
IO = 6mA, VID = -200mV
Full
-
0.27
0.4
V
Receiver Output Low Current
IOL
VO = 1V, VID = -200mV
Full
15
22
-
mA
Three-State (High Impedance)
Receiver Output Current
IOZR
0V ≤ VO ≤ VCC
Full
-1
0.01
1
µA
Receiver Short-Circuit Current
IOSR
0V ≤ VO ≤ VCC
Full
±12
-
±110
mA
DE = VCC, RE = 0V or VCC,
DI = 0V or VCC
Full
-
2.3
4.5
mA
DE = 0V, RE = VCC, DI = 0V or VCC
Full
-
10
50
µA
Human Body Model, 1/2 Duplex
from Bus Pins to
Full Duplex
GND
25
-
±16.5
-
kV
25
-
±15
-
kV
Human Body Model, per JEDEC
25
-
±8
-
kV
Machine Model
25
-
±700
-
V
SUPPLY CURRENT
No-Load Supply Current (Note 9)
Shutdown Supply Current
ICC
ISHDN
ESD PERFORMANCE
RS-485 Pins (A, Y, B, Z, A/Y, B/Z)
All Pins
DRIVER SWITCHING CHARACTERISTICS (250kbps Versions; ISL32470E and ISL32472E)
Driver Differential Output Delay
tPLH, tPHL
RD = 54Ω, CD = 50pF (Figure 6)
Full
-
320
450
ns
Driver Differential Output Skew
tSKEW
RD = 54Ω, CD = 50pF (Figure 6)
Full
-
6
30
ns
Driver Differential Rise or Fall Time
tR, tF
RD = 54Ω, CD = 50pF (Figure 6)
Full
400
650
1200
ns
FN7784 Rev 2.00
Feb 14, 2019
Page 6 of 21
ISL32470E, ISL32472E, ISL32475E, ISL32478E
Electrical Specifications Test Conditions: VCC = 4.5V to 5.5V; unless otherwise specified. Typical values are VCC = 5V, TA = +25°C
(Note 8). Boldface limits apply over the operating temperature range, -40°C to +85°C. (Continued)
PARAMETER
Maximum Data Rate
TEMP
(°C)
MIN
(Note 16)
TYP
MAX
(Note 16)
UNIT
CD = 820pF (Figure 8)
Full
0.25
1.5
-
Mbps
SYMBOL
fMAX
TEST CONDITIONS
Driver Enable to Output High
tZH
SW = GND (Figure 7), (Note 11)
Full
-
-
1200
ns
Driver Enable to Output Low
tZL
SW = VCC (Figure 7), (Note 11)
Full
-
-
1200
ns
Driver Disable from Output Low
tLZ
SW = VCC (Figure 7)
Full
-
-
120
ns
Driver Disable from Output High
tHZ
SW = GND (Figure 7)
Full
-
-
120
ns
(Note 13)
Full
60
160
600
ns
Time to Shutdown
tSHDN
Driver Enable from Shutdown to
Output High
tZH(SHDN)
SW = GND (Figure 7), (Notes 13, 14)
Full
-
-
2500
ns
Driver Enable from Shutdown to
Output Low
tZL(SHDN)
SW = VCC (Figure 7), (Notes 13, 14)
Full
-
-
2500
ns
DRIVER SWITCHING CHARACTERISTICS (1Mbps Versions; ISL32475E)
Driver Differential Output Delay
tPLH, tPHL
RD = 54Ω, CD = 50pF (Figure 6)
Full
-
70
125
ns
Driver Differential Output Skew
tSKEW
RD = 54Ω, CD = 50pF (Figure 6)
Full
-
4.5
15
ns
Driver Differential Rise or Fall Time
tR, tF
RD = 54Ω, CD = 50pF (Figure 6)
Full
70
170
300
ns
Maximum Data Rate
fMAX
CD = 820pF (Figure 8)
Full
1
4
-
Mbps
Driver Enable to Output High
tZH
SW = GND (Figure 7), (Note 11)
Full
-
-
350
ns
Driver Enable to Output Low
tZL
SW = VCC (Figure 7), (Note 11)
Full
-
-
300
ns
Driver Disable from Output Low
tLZ
SW = VCC (Figure 7)
Full
-
-
120
ns
Driver Disable from Output High
tHZ
SW = GND (Figure 7)
Full
-
-
120
ns
(Note 13)
Full
60
160
600
ns
Time to Shutdown
tSHDN
Driver Enable from Shutdown to
Output High
tZH(SHDN)
SW = GND (Figure 7), (Notes 13, 14)
Full
-
-
2000
ns
Driver Enable from Shutdown to
Output Low
tZL(SHDN)
SW = VCC (Figure 7), (Notes 13, 14)
Full
-
-
2000
ns
DRIVER SWITCHING CHARACTERISTICS (15Mbps Versions; ISL32478E)
Driver Differential Output Delay
tPLH, tPHL
RD = 54Ω, CD = 50pF (Figure 6)
Full
-
21
45
ns
Driver Differential Output Skew
tSKEW
RD = 54Ω, CD = 50pF (Figure 6)
Full
-
3
6
ns
Driver Differential Rise or Fall Time
tR, tF
RD = 54Ω, CD = 50pF (Figure 6)
Full
5
17
30
ns
Maximum Data Rate
fMAX
CD = 470pF (Figure 8)
Full
15
25
-
Mbps
Driver Enable to Output High
tZH
SW = GND (Figure 7), (Note 11)
Full
-
-
100
ns
Driver Enable to Output Low
tZL
SW = VCC (Figure 7), (Note 11)
Full
-
-
100
ns
Driver Disable from Output Low
tLZ
SW = VCC (Figure 7)
Full
-
-
120
ns
Driver Disable from Output High
tHZ
SW = GND (Figure 7)
Full
-
-
120
ns
(Note 13)
Full
60
160
600
ns
Time to Shutdown
tSHDN
Driver Enable from Shutdown to
Output High
tZH(SHDN)
SW = GND (Figure 7), (Notes 13, 14)
Full
-
-
2000
ns
Driver Enable from Shutdown to
Output Low
tZL(SHDN)
SW = VCC (Figure 7), (Notes 13, 14)
Full
-
-
2000
ns
FN7784 Rev 2.00
Feb 14, 2019
Page 7 of 21
ISL32470E, ISL32472E, ISL32475E, ISL32478E
Electrical Specifications Test Conditions: VCC = 4.5V to 5.5V; unless otherwise specified. Typical values are VCC = 5V, TA = +25°C
(Note 8). Boldface limits apply over the operating temperature range, -40°C to +85°C. (Continued)
PARAMETER
SYMBOL
TEST CONDITIONS
TEMP
(°C)
MIN
(Note 16)
TYP
MAX
(Note 16)
UNIT
RECEIVER SWITCHING CHARACTERISTICS (250kbps Versions; ISL32470E and ISL32472E)
Maximum Data Rate
fMAX
(Figure 9)
Full
0.25
5
-
Mbps
Receiver Input to Output Delay
tPLH, tPHL
(Figure 9)
Full
-
200
280
ns
Receiver Skew |tPLH - tPHL|
tSKD
(Figure 9)
Full
-
4
10
ns
Receiver Enable to Output Low
tZL
RL = 1kΩ, CL = 15pF, SW = VCC (Figure 10),
(Note 12)
Full
-
-
50
ns
Receiver Enable to Output High
tZH
RL = 1kΩ, CL = 15pF, SW = GND (Figure 10),
(Note 12)
Full
-
-
50
ns
Receiver Disable from Output Low
tLZ
RL = 1kΩ, CL = 15pF, SW = VCC (Figure 10)
Full
-
-
50
ns
Receiver Disable from Output High
tHZ
RL = 1kΩ, CL = 15pF, SW = GND (Figure 10)
Full
-
-
50
ns
(Note 13)
Full
60
160
600
ns
Time to Shutdown
tSHDN
Receiver Enable from Shutdown to
Output High
tZH(SHDN)
RL = 1kΩ, CL = 15pF, SW = GND (Figure 10),
(Notes 13, 15)
Full
-
-
2000
ns
Receiver Enable from Shutdown to
Output Low
tZL(SHDN)
RL = 1kΩ, CL = 15pF, SW = VCC (Figure 10),
(Notes 13, 15)
Full
-
-
2000
ns
RECEIVER SWITCHING CHARACTERISTICS (1Mbps Versions; ISL32475E)
Maximum Data Rate
Receiver Input to Output Delay
Receiver Skew |tPLH - tPH|
fMAX
(Figure 9)
Full
1
15
-
Mbps
tPLH, tPHL
(Figure 9)
Full
-
90
150
ns
tSKD
(Figure 9)
Full
-
4
10
ns
Receiver Enable to Output Low
tZL
RL = 1kΩ, CL = 15pF, SW = VCC (Figure 10),
(Note 12)
Full
-
-
50
ns
Receiver Enable to Output High
tZH
RL = 1kΩ, CL = 15pF, SW = GND (Figure 10),
(Note 12)
Full
-
-
50
ns
Receiver Disable from Output Low
tLZ
RL = 1kΩ, CL = 15pF, SW = VCC (Figure 10)
Full
-
-
50
ns
Receiver Disable from Output High
tHZ
RL = 1kΩ, CL = 15pF, SW = GND (Figure 10)
Full
-
-
50
ns
(Note 13)
Full
60
160
600
ns
Time to Shutdown
tSHDN
Receiver Enable from Shutdown to
Output High
tZH(SHDN)
RL = 1kΩ, CL = 15pF, SW = GND (Figure 10),
(Notes 13, 15)
Full
-
-
2000
ns
Receiver Enable from Shutdown to
Output Low
tZL(SHDN)
RL = 1kΩ, CL = 15pF, SW = VCC (Figure 10),
(Notes 13, 15)
Full
-
-
2000
ns
RECEIVER SWITCHING CHARACTERISTICS (15Mbps Versions; ISL32478E)
Maximum Data Rate
Receiver Input to Output Delay
Receiver Skew |tPLH - tPHL |
fMAX
(Figure 9)
Full
15
25
-
Mbps
tPLH, tPHL
(Figure 9)
Full
-
35
70
ns
tSKD
(Figure 9)
Full
-
4
10
ns
Receiver Enable to Output Low
tZL
RL = 1kΩ, CL = 15pF, SW = VCC (Figure 10),
(Note 12)
Full
-
-
50
ns
Receiver Enable to Output High
tZH
RL = 1kΩ, CL = 15pF, SW = GND (Figure 10),
(Note 12)
Full
-
-
50
ns
Receiver Disable from Output Low
tLZ
RL = 1kΩ, CL = 15pF, SW = VCC (Figure 10)
Full
-
-
50
ns
Receiver Disable from Output High
tHZ
RL = 1kΩ, CL = 15pF, SW = GND (Figure 10)
Full
-
-
50
ns
FN7784 Rev 2.00
Feb 14, 2019
Page 8 of 21
ISL32470E, ISL32472E, ISL32475E, ISL32478E
Electrical Specifications Test Conditions: VCC = 4.5V to 5.5V; unless otherwise specified. Typical values are VCC = 5V, TA = +25°C
(Note 8). Boldface limits apply over the operating temperature range, -40°C to +85°C. (Continued)
PARAMETER
TEMP
(°C)
MIN
(Note 16)
TYP
MAX
(Note 16)
UNIT
(Note 13)
Full
60
160
600
ns
SYMBOL
Time to Shutdown
tSHDN
TEST CONDITIONS
Receiver Enable from Shutdown to
Output High
tZH(SHDN)
RL = 1kΩ, CL = 15pF, SW = GND (Figure 10),
(Notes 13, 15)
Full
-
-
2000
ns
Receiver Enable from Shutdown to
Output Low
tZL(SHDN)
RL = 1kΩ, CL = 15pF, SW = VCC (Figure 10),
(Notes 13, 15)
Full
-
-
2000
ns
NOTES:
8. 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.
9. Supply current specification is valid for loaded drivers when DE = 0V.
10. Applies to peak current. See “Typical Performance Curves” beginning on page 5 for more information.
11. Keep RE = 0 to prevent the device from entering shutdown.
12. The RE signal high time must be short enough (typically 600ns to ensure that the device enters shutdown.
15. Set the RE signal high time >600ns to ensure that the device enters shutdown.
16. Compliance to datasheet limits is assured by one or more methods: production test, characterization, and/or design.
17. Tested according to TIA/EIA-485-A, Section 4.2.6 (±80V for 15µs at a 1% duty cycle).
18. See the Caution statement in “Absolute Maximum Ratings” on page 5.
Test Circuits and Waveforms
VCC
RL/2
DE
DI
VCC
Z
DI
VOD
D
Y
FIGURE 5A. VOD AND VOC
Z
VOC
VCM
VOD
D
Y
RL/2
375Ω
RL/2
DE
VOC
RL/2
375Ω
FIGURE 5B. VOD AND VOC WITH COMMON-MODE LOAD
FIGURE 5. DC DRIVER TEST CIRCUITS
FN7784 Rev 2.00
Feb 14, 2019
Page 9 of 21
ISL32470E, ISL32472E, ISL32475E, ISL32478E
Test Circuits and Waveforms (Continued)
3V
DI
1.5V
1.5V
0V
VCC
DE
tPLH
Z
DI
CD
D
RD
Y
tPHL
OUT (Z)
VOH
OUT (Y)
VOL
SIGNAL
GENERATOR
90%
DIFF OUT (Y - Z)
+VOD
90%
10%
10%
tR
-VOD
tF
SKEW = |tPLH - tPHL|
FIGURE 6A. TEST CIRCUIT
FIGURE 6B. MEASUREMENT POINTS
FIGURE 6. DRIVER PROPAGATION DELAY AND DIFFERENTIAL TRANSITION TIMES
DE
Z
DI
110Ω
VCC
D
SIGNAL
GENERATOR
SW
Y
GND
CL
3V
DE
(Note 13)
1.5V
0V
tZH, tZH(SHDN)
tHZ
OUTPUT HIGH
(Note 13)
OUTPUT
RE
DI
SW
CL (pF)
tHZ
Y/Z
X
1/0
GND
50
tLZ
Y/Z
tZH
Y/Z
0 (Note 11)
tZL
Y/Z
tZH(SHDN)
tZL(SHDN)
X
0/1
VCC
50
1/0
GND
100
0 (Note 11)
0/1
VCC
100
Y/Z
1 (Note 14)
1/0
GND
100
Y/Z
1 (Note 14)
0/1
VCC
100
VOH - 0.5V
2.3V
OUT (Y, Z)
PARAMETER
1.5V
VOH
0V
tZL, tZL(SHDN)
tLZ
(Note
VCC
OUT (Y, Z)
2.3V
VOL + 0.5V
OUTPUT LOW
FIGURE 7A. TEST CIRCUIT
VOL
FIGURE 7B. MEASUREMENT POINTS
FIGURE 7. DRIVER ENABLE AND DISABLE TIMES
VCC
DE
+
Z
DI
54Ω
D
Y
SIGNAL
GENERATOR
CD
3V
DI
VOD
0V
-
+VOD
DIFF OUT (Y - Z)
-VOD
FIGURE 8A. TEST CIRCUIT
0V
FIGURE 8B. MEASUREMENT POINTS
FIGURE 8. DRIVER DATA RATE
FN7784 Rev 2.00
Feb 14, 2019
Page 10 of 21
ISL32470E, ISL32472E, ISL32475E, ISL32478E
Test Circuits and Waveforms (Continued)
B
RE
750mV
15pF
B
R
A
0V
RO
0V
A
-750mV
tPLH
SIGNAL
GENERATOR
tPHL
SIGNAL
GENERATOR
VCC
50%
RO
50%
VCM
0V
FIGURE 9A. TEST CIRCUIT
FIGURE 9B. MEASUREMENT POINTS
FIGURE 9. RECEIVER PROPAGATION DELAY AND DATA RATE
RE
B
A
R
1kΩ
RO
SIGNAL
GENERATOR
RE
VCC
SW
15pF
3V
(Note
GND
1.5V
0V
tZH, tZH(SHDN)
(Note 13)
PARAMETER
1.5V
DE
A
SW
tHZ
0
+1.5V
GND
tLZ
0
-1.5V
VCC
tZH (Note 12)
0
+1.5V
GND
(Note
tZL (Note 12)
0
-1.5V
VCC
RO
tZH(SHDN) (Note 15)
0
+1.5V
GND
tZL(SHDN) (Note 15)
0
-1.5V
VCC
tHZ
OUTPUT HIGH
1.5V
RO
VOH - 0.5V
VOH
0V
tZL, tZL(SHDN)
tLZ
VCC
1.5V
VOL + 0.5V
OUTPUT LOW
FIGURE 10A. TEST CIRCUIT
VOL
FIGURE 10B. MEASUREMENT POINTS
FIGURE 10. RECEIVER ENABLE AND DISABLE TIMES
Typical Performance Curves VCC = 5V, TA = +25°C; unless otherwise specified.
3.6
RD = 20Ω
80
RD = 30Ω
DIFFERENTIAL OUTPUT VOLTAGE (V)
DRIVER OUTPUT CURRENT (mA)
90
+25°C
70
RD = 54Ω
+85°C
60
50
40
RD = 100Ω
30
20
10
0
0
1
2
3
4
5
DIFFERENTIAL OUTPUT VOLTAGE (V)
FIGURE 11. DRIVER OUTPUT CURRENT vs DIFFERENTIAL OUTPUT
VOLTAGE
FN7784 Rev 2.00
Feb 14, 2019
3.4
RD = 100Ω
3.2
3.0
2.8
2.6
RD = 54Ω
2.4
2.2
-40
-25
0
25
50
TEMPERATURE (°C)
75
85
FIGURE 12. DRIVER DIFFERENTIAL OUTPUT VOLTAGE vs
TEMPERATURE
Page 11 of 21
ISL32470E, ISL32472E, ISL32475E, ISL32478E
Typical Performance Curves VCC = 5V, TA = +25°C; unless otherwise specified. (Continued)
70
2.40
RECEIVER OUTPUT CURRENT (mA)
2.45
DE = VCC, RE = X
2.35
ICC (mA)
2.30
2.25
DE = GND, RE = GND
2.20
2.15
2.10
2.05
2.00
-40
-25
0
25
50
TEMPERATURE (°C)
75
VOL, +25°C
50
VOL, +85°C
40
30
20
10
0
-10
VOH, +85°C
-20
-30
85
FIGURE 13. SUPPLY CURRENT vs TEMPERATURE
60
VOH, +25°C
0
1
2
3
4
RECEIVER OUTPUT VOLTAGE (V)
5
FIGURE 14. RECEIVER OUTPUT CURRENT vs RECEIVER OUTPUT
VOLTAGE
1000
150
+85°C
VCC = 0V to 5.5V
800
Y OR Z = LOW
BUS PIN CURRENT (µA)
OUTPUT CURRENT (mA)
100
50
+25°C
0
-50
Y OR Z = HIGH
+25°C
-100
400
200
Y or Z
0
-200
-400
+85°C
-150
-60 -50 -40 -30 -20 -10
600
0
10
20
30
40
50
A/Y or B/Z
-600
-70 -60 -50 -40 -30 -20 -10 0
60
OUTPUT VOLTAGE (V)
FIGURE 15. DRIVER OUTPUT CURRENT vs SHORT-CIRCUIT VOLTAGE
FIGURE 16. BUS PIN CURRENT vs BUS PIN VOLTAGE
8
340
RD = 54Ω, CD = 50pF
RD = 54Ω, CD = 50pF
7
335
6
330
tPLH
325
SKEW (ns)
PROPAGATION DELAY (ns)
10 20 30 40 50 60 70
BUS PIN VOLTAGE (V)
320
315
tPHL
310
5
4
3
2
305
1
300
0
|tPLH - tPHL|
-40
-25
0
25
TEMPERATURE (°C)
50
75
FIGURE 17. DRIVER DIFFERENTIAL PROPAGATION DELAY vs
TEMPERATURE (ISL32470E, ISL32472E)
FN7784 Rev 2.00
Feb 14, 2019
85
-40
-25
0
50
25
TEMPERATURE (°C)
75
FIGURE 18. DRIVER DIFFERENTIAL SKEW vs TEMPERATURE
(ISL32470E, ISL32472E)
Page 12 of 21
85
ISL32470E, ISL32472E, ISL32475E, ISL32478E
Typical Performance Curves VCC = 5V, TA = +25°C; unless otherwise specified. (Continued)
4.0
85
RD = 54Ω, CD = 50pF
RD = 54Ω, CD = 50pF
3.5
75
SKEW (ns)
PROPAGATION DELAY (ns)
80
70
tPLH
65
3.0
tPHL
60
2.5
55
50
-40
0
-25
25
50
75
2.0
-40
85
|tPLH - tPHL|
-25
0
TEMPERATURE (°C)
FIGURE 19. DRIVER DIFFERENTIAL PROPAGATION DELAY vs
TEMPERATURE (ISL32475E)
RD = 54Ω, CD = 50pF
3.2
25
3.0
23
tPLH
21
19
tPHL
|tPLH - tPHL|
0
50
25
TEMPERATURE (°C)
-25
75
2.0
-40
85
A
15
B
VID = ±1V
10
5
VOLTAGE (V)
VOLTAGE (V)
0
25
50
TEMPERATURE (°C)
75
A
B
VID = ±1V
5
RO
0
RO
0
RO
0
5
RO
0
-5
-5
-15
-25
FIGURE 22. DRIVER DIFFERENTIAL SKEW vs TEMPERATURE
(ISL32478E)
5
-10
2.6
2.2
FIGURE 21. DRIVER DIFFERENTIAL PROPAGATION DELAY vs
TEMPERATURE (ISL32478E)
10
2.8
2.4
17
15
85
3.4
RD = 54Ω, CD = 50pF
15
-40
75
FIGURE 20. DRIVER DIFFERENTIAL SKEW vs TEMPERATURE
(ISL32475E)
SKEW (ns)
PROPAGATION DELAY (ns)
27
25
50
TEMPERATURE (°C)
-10
A
-15
B
TIME (1µs/DIV)
FIGURE 23. RECEIVER PERFORMANCE WITH ±15V CMV (ISL32470E,
ISL32472E)
FN7784 Rev 2.00
Feb 14, 2019
A
B
TIME (400ns/DIV)
FIGURE 24. RECEIVER PERFORMANCE WITH ±15V CMV
(ISL32475E)
Page 13 of 21
85
ISL32470E, ISL32472E, ISL32475E, ISL32478E
10
VID = ±1V
5
5
DRIVER OUTPUT (V)
RO
0
RO
0
-5
-10
A
-15
B
RD = 54Ω, CD = 50pF
DI
0
5
RO
0
3
2
1
0
-1
-2
-3
A/Y - B/Z
TIME (1µs/DIV)
TIME (20ns/DIV)
5
0
3
2
1
0
-1
-2
-3
RO
A/Y - B/Z
TIME (400ns/DIV)
FIGURE 27. DRIVER AND RECEIVER WAVEFORMS (ISL32475E)
FN7784 Rev 2.00
Feb 14, 2019
DRIVER OUTPUT (V)
0
DRIVER INPUT (V)
RECEIVER OUTPUT (V)
DRIVER OUTPUT (V)
DI
5
RECEIVER OUTPUT (V)
FIGURE 26. DRIVER AND RECEIVER WAVEFORMS (ISL32470E,
ISL32472E)
FIGURE 25. RECEIVER PERFORMANCE WITH ±15V CMV
(ISL32478E)
RD = 54Ω, CD = 50pF
5
RD = 54Ω, CD = 50pF
DI
5
0
5
0
3
2
1
0
-1
-2
-3
RO
DRIVER INPUT (V)
B
DRIVER INPUT (V)
A
15
VOLTAGE (V)
RECEIVER OUTPUT (V)
Typical Performance Curves VCC = 5V, TA = +25°C; unless otherwise specified. (Continued)
A/Y - B/Z
TIME (20ns/DIV)
FIGURE 28. DRIVER AND RECEIVER WAVEFORMS (ISL32478E)
Page 14 of 21
ISL32470E, ISL32472E, ISL32475E, ISL32478E
Application Information
RS-485 and RS-422 are differential (balanced) data
transmission standards used for 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 that allows only one driver and up to 10 (assuming
one-unit load devices) receivers on each bus. RS-485 is a true
multipoint standard that 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 specification requires that
drivers must handle bus contention without sustaining any
damage.
An 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 runs as long as
4000ft; thus, the wide CMR is necessary to handle ground
potential differences and voltages induced in the cable by
external fields.
The ISL3247xE devices are a family of ruggedized RS-485
transceivers that improves on the RS-485 basic requirements
and increases system reliability. The CMR increases to ±15V and
the RS-485 bus pins (receiver inputs and driver outputs) include
fault protection against voltages and transients up to ±60V.
Additionally, larger-than-required differential output voltages
(VOD) increase noise immunity, and the ±16.5kV built-in ESD
protection complements the fault protection.
Receiver (Rx) Features
These devices use a differential input receiver for maximum
noise immunity and common-mode rejection. Input sensitivity is
better than ±200mV, as required by the RS-422 and RS-485
specifications.
The receiver input (load) current surpasses the RS-422
specification of 3mA and is four times lower than the RS-485
Unit Load (UL) requirement of 1mA maximum. Therefore, these
products are known as one-quarter UL transceivers, and there
can be up to 128 of these devices on a network while still
complying with the RS-485 loading specification.
The receivers function with common-mode voltages as great as
±15V, making them ideal for industrial or long networks where
induced voltages are a realistic concern.
All the receivers include a full fail-safe function that ensures a
high-level receiver output if the receiver inputs are unconnected
(floating), shorted together, or connected to a terminated bus
with all the transmitters disabled (an idle bus).
The receiver outputs feature high drive levels (typically 22mA at
VOL = 1V) to ease the design of optically coupled isolated
interfaces.
The receivers easily meet the data rates supported by the
corresponding driver, and all receiver outputs are three-statable
using the active low RE input.
The receivers in the 250kbps versions (ISL32470E and
ISL32472E) and 1Mbps versions (ISL32475E) include noise
filtering circuitry to reject high-frequency signals. The ISL32475E
FN7784 Rev 2.00
Feb 14, 2019
version typically rejects pulses narrower than 50ns (equivalent to
20Mbps). The ISL32470E and ISL32472E reject pulses below
150ns (6.7Mbps).
Driver (Tx) Features
The RS-485/RS-422 driver is a differential output device that
delivers at least 1.5V across a 54Ω load (RS-485) and at least
2.4V across a 100Ω load (RS-422). The drivers feature low
propagation delay skew to maximize bit width and to minimize
EMI, and all drivers are three-statable using the active high DE
input.
The 250kbps and 1Mbps driver outputs are slew rate limited to
minimize EMI and reflections in unterminated or improperly
terminated networks. The ISL32478E driver outputs are not
limited, so faster output transition times allow data rates of at
least 15Mbps.
High Overvoltage (Fault) Protection
Increases Ruggedness
The ±60V fault protection (referenced to the IC GND) on the
RS-485 pins makes these transceivers some of the most rugged
on the market. This level of protection makes the ISL3247xE
perfect for applications where power (for example 24V and 48V
supplies) must be routed in the conduit with the data lines, or for
outdoor applications where large transients are likely to occur.
When power is routed with the data lines, even a momentary
short between the supply and data lines destroys an unprotected
device. The ±60V fault levels of this family are at least five times
higher than the levels specified for standard RS-485 ICs. The
ISL3247xE protection is active whether the Tx is enabled or
disabled, and even if the IC is powered down or if VCC and
Ground are floating.
If transients or voltages (including overshoots and ringing)
greater than ±60V are possible, additional external protection is
required.
Wide Common-Mode Voltage (CMV) Tolerance
Improves Operating Range
RS-485 networks operating in industrial complexes or over long
distances are susceptible to large CMV variations. Either of these
operating environments can suffer from large node-to-node
ground potential differences or CMV pickup from external
electromagnetic sources, and devices with only the minimum
required +12V to -7V CMR can malfunction. The ISL3247xE’s
extended ±15V CMR allows for operation in environments that
would overwhelm lesser transceivers. Additionally, the Rx does
not phase invert (erroneously change state), even with CMVs of
±40V or differential voltages as large as 40V.
High VOD Improves Noise Immunity and
Flexibility
The ISL3247xE driver design delivers larger differential output
voltages (VOD) than the RS-485 standard requires or than most
RS-485 transmitters can deliver. The typical ±2.5V VOD provides
more noise immunity than networks built using many other
transceivers.
Page 15 of 21
ISL32470E, ISL32472E, ISL32475E, ISL32478E
Another advantage of the large VOD is the ability to drive more
than two bus terminations, which allows use of the ISL3247xE in
star topologies and other multi-terminated, nonstandard network
topologies. Figure 11 on page 11 details the transmitter’s VOD vs
IOUT characteristic and includes load lines for four (30Ω) and six
(20Ω) 120Ω terminations. Figure 11 shows that the driver
typically delivers ±1.3V into six terminations, and the “Electrical
Specifications” ensure a VOD of ±0.8V at 21Ω across the full
temperature range. The RS-485 standard requires a minimum
1.5V VOD into two terminations, but the ISL3247xE delivers
RS-485 voltage levels with two to three times the number of
terminations.
Hot Plug Function
When a piece of equipment powers up, there is a period of time
when 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 can crash the bus. To
avoid crashes, the ISL3247xE devices incorporate a hot plug
function. Circuitry monitoring VCC ensures that, the Tx and Rx
outputs remain disabled during power-up and power-down if VCC
is less than ≈3.5V, regardless of the state of DE and RE. The
disabled Tx and Rx outputs allow the processor/ASIC to stabilize
and drive the RS-485 control lines to the proper states. Figure 29
illustrates the power-up and power-down performance of the
ISL3247xE compared to an RS-485 IC without the hot plug
feature.
RE = GND
2.8V
2.5
VCC
0
5.0
RL = 1kΩ
2.5
0
A/Y
ISL3247xE
ISL83088E
RL = 1kΩ
RO
ISL3247xE
5.0
2.5
0
RECEIVER OUTPUT (V)
DRIVER Y OUTPUT (V)
3.5V
5.0
VCC (V)
DE, DI = VCC
TIME
(40µs/DIV)
FIGURE 29. HOT PLUG PERFORMANCE (ISL3247xE) vs ISL83088E
WITHOUT HOT PLUG CIRCUITRY
ESD Protection
All pins on these devices include Class 3 (>8kV) Human Body
Model (HBM) ESD protection structures that can survive ESD
events commonly seen during manufacturing. Even so, the
RS-485 pins (driver outputs and receiver inputs) incorporate
more advanced structures that allow them to survive ESD
events in excess of ±16.5kV HBM (±15kV for the full-duplex
versions). The RS-485 pins are particularly vulnerable to ESD
strikes because they typically connect to an exposed port on the
exterior of the finished product. Touching the port pins or
FN7784 Rev 2.00
Feb 14, 2019
connecting a cable can cause an ESD event that destroys
unprotected ICs. The new ESD structures protect the device
whether or not it is powered up, and without interfering with the
exceptional ±15V CMR. The built-in ESD protection minimizes
the need for board-level protection structures (such as transient
suppression diodes) and the associated undesirable capacitive
load they present.
Data Rate, Cables, and Terminations
RS-485/RS-422 are intended for network lengths up to 4000ft,
but the maximum system data rate decreases as the
transmission length increases. The ISL32478E operating at
15Mbps can be used at lengths up to 150ft (46m), but the
distance can be increased to 328ft (100m) by operating at
10Mbps. The ISL32475E can operate at full data rates (1Mbps)
with lengths up to 800ft (244m). Jitter is the limiting parameter
at these faster data rates, so using encoded data streams (for
example, Manchester coded or Return-to-Zero) can allow
increased transmission distances. The ISL32470E and
ISL32472E can operate at 115kbps or less at the full 4000ft
(1220m) distance, or at the full data rate of 250kbps for lengths
up to 3000ft (915m). DC cable attenuation is the limiting
parameter, so using better-quality cables such as 22 AWG can
allow increased transmission distance.
Use twisted pair cables for RS-485/RS-422 networks. Twistedpair cables tend to pick up noise and other electromagnetically
induced voltages as common-mode signals that are effectively
rejected by the differential receivers in these ICs.
Note: Proper termination is imperative to minimize reflections
when using the ISL32478E. Short networks using the ISL32470E
and ISL32472E do not need to be terminated; however,
terminations are recommended unless power dissipation is an
overriding concern.
In point-to-point or point-to-multipoint networks (single driver on
the bus like RS-422), terminate the main cable in its
characteristic impedance (typically 120Ω) at the end farthest
from the driver. In multi-receiver applications, keep stubs
connecting receivers to the main cable as short as possible.
Multipoint (multi-driver) systems require the main cable to
terminate in its characteristic impedance at both ends. Stubs
connecting a transceiver to the main cable should be as short as
possible.
Built-In Driver Overload Protection
The RS-485 specification requires that drivers survive worst-case
bus contentions undamaged. These transceivers meet this
requirement through driver output short-circuit current limits and
on-chip thermal shutdown circuitry.
The driver output stages incorporate a double foldback
short-circuit current limiting scheme that ensures that the output
current never exceeds the RS-485 specification, even at the
common-mode and fault condition voltage range extremes. The
first foldback current level (≈70mA) is set to ensure that the
driver never folds back when driving loads with common-mode
voltages up to ±15V. The very low second foldback current
setting (≈9mA) minimizes power dissipation if the Tx is enabled
when a fault occurs.
Page 16 of 21
ISL32470E, ISL32472E, ISL32475E, ISL32478E
In the event of a major short-circuit condition, the ISL3247xE
thermal shutdown feature disables the drivers whenever the die
temperature becomes excessive. Thermal shutdown eliminates
the power dissipation, allowing the die to cool. The drivers
automatically re-enable after the die temperature drops by about
15°C. If the contention persists, the thermal shutdown/re-enable
cycle repeats until the fault is cleared. The receivers stay
operational during thermal shutdown.
Low Power Shutdown Mode
shutdown feature that reduces the already low quiescent ICC to a
10µA trickle. These devices enter 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 receiver for less than 60ns ensures that the
transceiver does not enter shutdown.
Note: The receiver and driver enable times increase when the
transceiver enables from shutdown. See Notes 11 through 15 for
more information.
These BiCMOS transceivers all use a fraction of the power
required by competitive devices, but they also include a
Die Characteristics
SUBSTRATE POTENTIAL (POWERED UP):
GND
PROCESS:
Si Gate BiCMOS
FN7784 Rev 2.00
Feb 14, 2019
Page 17 of 21
ISL32470E, ISL32472E, ISL32475E, ISL32478E
Revision History The revision history provided is for informational purposes only and is believed to be accurate, but not warranted.
Visit out website to make sure you have the latest revision.
DATE
REVISION
Feb 14, 2019
FN7784.2
Added Related Literature section to page 1.
Added tape and reel information and updated notes in ordering information table on page 3.
Updated “High Overvoltage (Fault) Protection Increases Ruggedness” section on page 15.
Removed Products section.
Updated disclaimer.
Mar 9, 2012
FN7784.1
Page 5 - Thermal Information, Thermal Resistance:
8 Ld SOIC Package Theta JA changed from 116 to 108
Page 14 - Updated Figure 15 to show Pos breakdown between 60V and 70V.
Page 19 - Updated Package Outline Drawing M8.15 to newest revision.
Jan 21, 2011
FN7784.0
Initial Release
FN7784 Rev 2.00
Feb 14, 2019
CHANGE
Page 18 of 21
ISL32470E, ISL32472E, ISL32475E, ISL32478E
Package Outline Drawings
For the most recent package outline drawing, see M14.15.
M14.15
14 LEAD NARROW BODY SMALL OUTLINE PLASTIC PACKAGE
Rev 1, 10/09
8.65
A 3
4
0.10 C A-B 2X
6
14
DETAIL"A"
8
0.22±0.03
D
6.0
3.9
4
0.10 C D 2X
0.20 C 2X
7
PIN NO.1
ID MARK
5
0.31-0.51
B 3
(0.35) x 45°
4° ± 4°
6
0.25 M C A-B D
TOP VIEW
0.10 C
1.75 MAX
H
1.25 MIN
0.25
GAUGE PLANE C
SEATING PLANE
0.10 C
0.10-0.25
1.27
SIDE VIEW
(1.27)
DETAIL "A"
(0.6)
NOTES:
1. Dimensions are in millimeters.
Dimensions in ( ) for Reference Only.
2. Dimensioning and tolerancing conform to AMSEY14.5m-1994.
3. Datums A and B to be determined at Datum H.
(5.40)
4. Dimension does not include interlead flash or protrusions.
Interlead flash or protrusions shall not exceed 0.25mm per side.
5. The pin #1 indentifier may be either a mold or mark feature.
(1.50)
6. Does not include dambar protrusion. Allowable dambar protrusion
shall be 0.10mm total in excess of lead width at maximum condition.
7. Reference to JEDEC MS-012-AB.
TYPICAL RECOMMENDED LAND PATTERN
FN7784 Rev 2.00
Feb 14, 2019
Page 19 of 21
ISL32470E, ISL32472E, ISL32475E, ISL32478E
M8.15
For the most recent package outline drawing, see 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.
FN7784 Rev 2.00
Feb 14, 2019
Page 20 of 21
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