DATASHEET
ISL32704E
FN8860
Rev.4.00
Feb 12, 2018
Ultra-Low EMI, Smallest Package Isolated RS-485 Transceiver
The ISL32704E is a galvanically isolated, differential bus
transceiver designed for bidirectional data transmission and
meeting the RS-485 and RS-422 standards for balanced
communication. Each of the bus terminals, A and B, is
protected against ±15kV ESD strikes without latch-up.
Features
The device uses Giant Magnetoresistance (GMR) as isolation
technology. A unique ceramic/polymer composite barrier
provides excellent isolation and virtually unlimited barrier life.
• 3V to 5V power supplies
The part is available in a 16 Ld QSOP package offering
unprecedented miniaturization, and in a 16 Ld wide-body SOIC
package providing true 8 millimeter creepage distance.
• 4Mbps data rate
• 2.5kVRMS isolation per UL 1577
• 600VRMS working voltage per VDE 0884
• Single unit load receiver input
• Driver drives up to 150 unit loads
• 50kV/µs (typical), 30kV/µs (minimum) common-mode
transient immunity
The ISL32704E delivers a minimum differential output voltage
of 1.5V into a 54Ω differential load for excellent data integrity
over long cable lengths.
• 44000 years barrier life
The device is compatible with 3V and 5V input supplies,
allowing interface to standard microcontrollers without
additional level shifting.
• -40°C to +85°C temperature range
Current limiting and thermal shutdown features protect
against output short circuits and bus contention that may
cause excessive power dissipation. Receiver inputs feature a
“fail-safe if open” design, ensuring a logic high R-output if A/B
are floating.
Related Literature
• 15kV ESD bus-pin protection
• Thermal shutdown protection
• Meets or exceeds ANSI RS-485
• 16 Ld QSOP and 0.3” true 8mm 16 Ld SOIC packages
• UL 1577 recognized
• VDE V0884-10 certified
Applications
• Factory automation
For a full list of related documents, visit our website
• ISL32704E product page
• Security networks
• Building environmental control systems
• Industrial/process control networks
• Level translators (i.e., RS-232 to RS-485)
Isolation
3.3V Barrier 5V
100n
100n
1
VDD1
2
4
5
6
16
VDD2
VDD2X
R
ISODE
RE
XDE
DE
A
D
GND1
3
Isolation
5V Barrier 3.3V
100n
11
15
542R
12
9
10
B
13
ISOR
GND2
135R
120R
VDD2
11
VDD2X
15
ISODE
12
XDE
9
A
10
B
13
ISOR
VDD1
GND2
GND1
542R
14
14
ISL32704EIAZ
1
3
4
5
6
VDD1
100n
16
A
RE
DE
D
GND1
2,8
B
ISODE
GND2
9,15
ISL32704EIBZ
DE
D
2
4
5
6
3
16
VDD2
12
13
Isolation
5V Barrier 3.3V
100n
542R
VDD2
R
R
RE
ISL32704EIAZ
Isolation
3.3V Barrier 5V
100n
100n
1
16
12
135R
10
120R
13
10
542R
100n
1
VDD1
R
A
RE
B
ISODE
GND2
9,15
DE
D
3
4
5
6
GND1
2,8
ISL32704EIBZ
FIGURE 1. TYPICAL ISOLATED HIGH-SPEED RS-485 APPLICATIONS
FN8860 Rev.4.00
Feb 12, 2018
Page 1 of 14
ISL32704E
Ordering Information
PART NUMBER
(Notes 3, 4)
TEMP. RANGE
(°C)
PART MARKING
PACKAGE
(RoHS COMPLIANT)
PKG. DWG. #
ISL32704EIAZ (Note 1)
32704EIAZ
-40 to +85
16 Ld QSOP
M16.15B
ISL32704EIBZ (Note 2)
32704EIBZ
-40 to +85
16 Ld SOIC
M16.3A
ISL32704EVAL1Z
Evaluation board for ISL32704EIAZ
ISL32704EVAL2Z
Evaluation board for ISL32704EIBZ
NOTES:
1. Add “-T7A” suffix for 250 unit or “-T” suffix for 2500 unit tape and reel options. Refer to TB347 for details about reel specifications.
2. Add “-T7A” suffix for 250 unit or “-T” suffix for 1000 unit tape and reel options. Refer to TB347 for details about reel specifications.
3. These Pb-free plus anneal products employ special Pb-free material sets; molding compounds/die attach materials and 100% matte tin plate
termination finish, which are 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.
4. For Moisture Sensitivity Level (MSL), see the ISL32704E product information page. For more information about MSL, see TB363.
Pin Configurations
ISL32704E
(16 LD WB-SOIC)
TOP VIEW
ISL32704E
(16 LD QSOP)
TOP VIEW
VDD1 1
R 2
16 VDD2
VDD1 1
16 VDD2
15 ISODE
GND1 2
15 GND2
GND1 3
14 GND2
R 3
RE 4
13 ISOR
RE 4
13 B
DE 5
12 XDE
DE 5
12 A
D 6
11 VDD2X
D 6
NC 7
10 B
NC 7
NC 8
9 A
GND1 8
D
14 NC
ISODE
11 NC
10 ISODE
9 GND2
DE
ISODE
XDE
DE
D
B
A
R
RE
B
A
R
ISOR
RE
Truth Table
Truth Table
TRANSMITTING
INPUTS
RECEIVING
OUTPUTS
INPUTS
OUTPUT
RE
DE
D
ISODE
B
A
RE
DE
A-B
R
X
1
1
1
0
1
0
0
≥0.2V
1
X
1
0
1
1
0
0
0
≤-0.2V
0
0
0
X
0
High-Z
High-Z
0
0
Inputs Open/Shorted
1
1
0
X
0
High-Z
High-Z
1
1
X
High-Z
1
0
X
High-Z
FN8860 Rev.4.00
Feb 12, 2018
Page 2 of 14
ISL32704E
Pin Descriptions
PIN NUMBER
16 Ld
SOIC
16 Ld
QSOP
PIN
NAME
1
1
VDD1
3
2
R
2, 8
3
GND1
4
4
RE
Receiver output enable. R is enabled when RE is low. R is high impedance when RE is high. If the Rx enable function is
not required, connect RE directly to GND1.
5
5
DE
Driver output enable. The driver outputs, A and B, are enabled when DE is high. They are high impedance when DE is low.
If the Tx enable function is not required, connect DE to VDD1 (Pin 1) through a 1kΩ or greater resistor.
6
6
D
Driver input. A low on D forces output A low and output B high. A high on D forces output A high and output B low.
7, 11, 14
7, 8
NC
No internal connection.
12
9
A
±15kV ESD protected, noninverting bus terminal. This pin is the noninverting receiver input when DE = 0 and the
noninverting driver output when DE = 1.
13
10
B
±15kV ESD protected, inverting bus terminal. This pin is the inverting receiver input when DE = 0 and the inverting driver
output when DE = 1.
-
11
-
12
XDE
External driver enable. Allows for enabling the driver from the bus side. Connect this pin to ISODE to control the driver
from the controller side. This pin must not be left floating.
-
13
ISOR
Isolated receiver output for test purpose only. This pin is used for testing and should be left unconnected.
9, 15
14
GND2
Output power supply ground return. Dual ground pins are connected internally.
10
15
ISODE
Isolated DE output.
16
16
VDD2
Isolator output power supply.
FUNCTION
Input power supply.
Receiver output. R is high when A-B ≥ 200mV, and when A and B are floating. R is low when A-B ≤ -200mV.
Input power supply ground return. Dual ground pins are connected internally.
VDD2X Transceiver power supply. Connect to VDD2 (Pin 16).
Typical Operating Circuits
100n
3.3V ISOLATION
5V
BARRIER
1
VDD1
100n
3.3V ISOLATION 5V
BARRIER
1
16
VDD1
VDD2
100n
11
16
VDD2X VDD2
5 DE
5 DE
ISODE 15
XDE 12
ISODE 10
1.09k
A 9
6 D
100n
1.09k
A 12
6 D
127R
2 R
4 RE
3
GND2
14
B 13
4 RE
ISOR 13
GND1
127R
3 R
B 10
1.09k
GND1
2,8
ISL32704EIAZ
GND2
1.09k
9,15
ISL32704EIBZ
FIGURE 2. TYPICAL OPERATING CIRCUITS
FN8860 Rev.4.00
Feb 12, 2018
Page 3 of 14
ISL32704E
Absolute Maximum Ratings
Thermal Information
(Note 17)
Supply Voltages (Note 7)
VDD1 to GND1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to +7V
VDD2 to GND2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7V
Input Voltages, D, DE, RE. . . . . . . . . . . . . . . . . . . . . . . -0.5V to (VDD1 +0.5V)
Input/Output Voltages
A, B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -8V to +12.5V
R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to (VDD1 +1V)
Short-Circuit Duration, A, B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Continuous
ESD Rating . . . . . . . . . . . . . . . . . . . . See “ESD PERFORMANCE” on page 5
Thermal Resistance (Typical)
JA (°C/W) JC (°C/W)
16 Ld WB-SOIC Package (Notes 5, 6) . . . .
34
17
16 Ld QSOP Package (Notes 5, 6) . . . . . . .
63
35
Maximum Junction Temperature (Plastic Package) . . . .-55°C to +150°C
Maximum Storage Temperature Range . . . . . . . . . . . . . .-55°C to +150°C
Maximum Power Dissipation (WB-SOIC) . . . . . . . . . . . . . . . . . . . . . .800mW
Maximum Power Dissipation (QSOP). . . . . . . . . . . . . . . . . . . . . . . . .675mW
Solder Profile . . . . . . . . . . . . . . . . . . . . . . . . . Per JEDEC J-STD-020C, MSL1
Pb-Free Reflow Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see TB493
Recommended Operating Conditions
Supply Voltages
VDD1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0V to 5.5V
VDD2, VDD2X . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5V to 5.5V
High-Level Digital Input Voltage, VIH
VDD1 = 3.3V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4V to VDD1
VDD1 = 5.0V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0V to VDD1
Low-Level Digital Input Voltage, VIL . . . . . . . . . . . . . . . . . . . . . . . .0V to 0.8V
Input Voltage at any Bus Terminal
(separately or common-mode), VI, VIC . . . . . . . . . . . . . . . . . . . .-7V to 12V
Differential Input Voltage (Note 8), VID . . . . . . . . . . . . . . . . . . . . .-7V to 12V
High-Level Output Current (Driver), IOH . . . . . . . . . . . . . . . . . . . . . . . . 60mA
High-Level Digital Output Current (Receiver), IOH . . . . . . . . . . . . . . . . . 8mA
Low-Level Output Current (Driver), IOL . . . . . . . . . . . . . . . . . . . . . . . . . -60mA
Low-Level Digital Output Current (Receiver), IOL . . . . . . . . . . . . . . . . . -8mA
Junction Temperature, TJ . . . . . . . . . . . . . . . . . . . . . . . . . . .-40°C to +100°C
Ambient Operating Temperature, TA . . . . . . . . . . . . . . . . . . -40°C to +85°C
Digital Input Signal Rise and Fall Times, tIR, tIF . . . . . . . . . . . . . . DC Stable
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:
5. JA is measured in free air with the component soldered to a double-sided board.
6. For JC, the “case temp” location is the center of the package top side.
Electrical Specifications
Test Conditions: TMIN to TMAX, VDD1 = VDD2 = 4.5V to 5.5V; unless otherwise stated
(see (Note 7).
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
TYP
MAX
UNIT
VDD2
V
DC CHARACTERISTICS
Driver Line Output Voltage (VA, VB) (Note 7)
VO
No load
Driver Differential Output Voltage (Note 8)
VOD1
No load
Driver Differential Output Voltage (Note 8)
VOD2
RL = 54Ω
Change in Magnitude of Differential Output Voltage (Note 13)
VOD
RL = 54Ω or 100Ω
Driver Common-Mode Output Voltage
VOC
RL = 54Ω or 100Ω
Change in Magnitude of Driver Common-Mode Output Voltage
(Note 13)
VOC
RL = 54Ω or 100Ω
Bus Input Current (A, B) (Notes 10, 14)
IIN2
DE = 0V
1.5
V
VDD2
V
0.01
0.2
V
3
V
0.20
V
0.01
VIN = 12V
VIN = -7V
High-Level Input Current (D, DE, RE)
IIH
VI = 3.5V
Low-Level Input Current (D, DE, RE)
IIL
VI = 0.4V
IOS
DE = VDD1, -7V ≤ VA or VB ≤ 12V
Absolute Short-Circuit Output Current
VDD2
2.3
1
-0.8
10
-10
IDD1
VDD1 = 5V
4
VDD1 = 3.3V
3
Positive-Going Input Threshold Voltage
V TH+
-7V ≤ VCM ≤ 12V
Negative-Going Input Threshold Voltage
V TH-
-7V ≤ VCM ≤ 12V
FN8860 Rev.4.00
Feb 12, 2018
µA
µA
Supply Current
-200
mA
mA
±250
mA
6
mA
4
mA
200
mV
mV
Page 4 of 14
ISL32704E
Electrical Specifications
Test Conditions: TMIN to TMAX, VDD1 = VDD2 = 4.5V to 5.5V; unless otherwise stated
(see (Note 7). (Continued)
PARAMETER
Receiver Input Hysteresis
SYMBOL
VHYS
TEST CONDITIONS
MIN
VCM = 0V
TYP
MAX
UNIT
70
mV
9
Differential Bus Input Capacitance
CD
Receiver Output High Voltage
VOH
IO = -20µA, VID = -50mV
Receiver Output Low Voltage
VOL
IO = +20µA, VID = -200mV
High impedance Output Current
IOZ
0.4V ≤ VO ≤ (VDD2 - 0.5)
-1
Receiver Input Resistance
RIN
-7V ≤ VCM ≤ 12V
12
Supply Current
IDD2
DE = VDD1 , no load
12
pF
VDD1 - 0.2 VDD1
V
0.2
V
1
µA
16
mA
kΩ
5
ESD PERFORMANCE
RS-485 Bus Pins (A, B)
Human body model discharge to GND2
±15
kV
All Pins (R, RE, D, DE)
Human body model discharge to GND1
±2
kV
SWITCHING CHARACTERISTICS
VDD1 = 5V, VDD2 = 5V
Data Rate
Propagation Delay (Notes 8, 15)
Pulse Skew (Notes 8, 16)
DR
RL = 54Ω, CL = 50pF
4
Mbps
tPD
VO = -1.5V to 1.5V, CL = 15pF
48
150
ns
tSK (P)
VO = -1.5V to 1.5V, CL = 15pF
6
15
ns
Output Enable Time to High Level
tPZH
CL = 15pF
33
50
ns
Output Enable Time to Low Level
tPZL
CL = 15pF
33
50
ns
Output Disable Time from High Level
tPHZ
CL = 15pF
33
50
ns
Output Disable Time from Low Level
tPLZ
CL = 15pF
33
50
ns
Common-Mode Transient Immunity
CMTI
VCM = 1500 VDC, tTRANSIENT = 25ns
30
4
50
kV/µs
VDD1 = 3.3V, VDD2 = 5V
Data Rate
DR
RL = 54Ω, CL = 50pF
Propagation Delay (Notes 9, 15)
tPD
VO = -1.5V to 1.5V, CL = 15pF
tSK (P)
Pulse Skew (Notes 9, 16)
Mbps
48
150
ns
VO = -1.5V to 1.5V, CL = 15pF
6
20
ns
tPZH
CL = 15pF
33
50
ns
Output Enable Time to Low Level
tPZL
CL = 15pF
33
50
ns
Output Disable Time from High Level
tPHZ
CL = 15pF
33
50
ns
Output Disable Time from Low Level
tPLZ
CL = 15pF
33
50
Common-Mode Transient Immunity
CMTI
VCM = 1500 VDC, tTRANSIENT = 25ns
Output Enable Time to High Level
30
50
ns
kV/µs
NOTES: (applies to both driver and receiver sections)
7. All voltages on the isolator primary side are with respect to GND1. All line voltages and common-mode voltages on the isolator secondary or bus side
are with respect to GND2.
8. Differential I/O voltage is measured at the noninverting bus terminal A with respect to the inverting terminal B.
9. Skew limit is the maximum propagation delay difference between any two devices at +25°C.
10. The power-off measurement in ANSI Standard EIA/TIA-422-B applies to disabled outputs only and is not applied to combined inputs and outputs.
11. All typical values are at VDD1, VDD2 = 5V or VDD1 = 3.3V and TA = +25°C.
12. -7V < VCM < 12V; 4.5 < VDD < 5.5V.
13. VOD and VOC are the changes in magnitude of VOD and VOC respectively, that occur when the input is changed from one logic state to the other.
14. This applies for both power-on and power-off; refer to ANSI standard RS-485 for exact condition. The EIA/TIA-422 -B limit does not apply for a
combined driver and receiver terminal.
15. Includes 10ns read enable time. Maximum propagation delay is 25ns after read assertion.
16. Pulse skew is defined as |tPLH - tPHL| of each channel.
17. The relevant test and measurement methods are given in the “Electromagnetic Compatibility” on page 7.
18. External magnetic field immunity is improved by this factor if the field direction is “end-to-end” rather than “pin-to-pin” (see diagram in
“Electromagnetic Compatibility” on page 7).
FN8860 Rev.4.00
Feb 12, 2018
Page 5 of 14
ISL32704E
Insulation Specifications
PARAMETER
SYMBOL
Creepage Distance (External)
TEST CONDITIONS
Per IEC 60601
MIN
TYP
WB-SOIC 8.03
8.3
QSOP
Total Barrier Thickness (Internal)
RIO
500V
Barrier Capacitance
CIO
f = 1MHz
240VRMS, 60Hz
Leakage Current
UNIT
mm
3.2
12
Barrier Resistance
MAX
mm
13
µm
>1014
Ω
7
pF
0.2
µARMS
Comparative Tracking Index
CTI
Per IEC 60112
≥175
VRMS
High Voltage Endurance
(Maximum Barrier Voltage for Indefinite Life)
VIO
At maximum operating temperature
1000
VRMS
1500
VDC
Barrier Life
100°C, 1000VRMS, 60% CL activation energy
44000
Years
Magnetic Field Immunity (Note 17)
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
TYP
MAX
UNIT
VDD1 = 5V, VDD2 = 5V
Power Frequency Magnetic Immunity
HPF
50Hz/60Hz
2800
3500
A/m
Pulse Magnetic Field Immunity
HPM
tP = 8µs
4000
4500
A/m
Damped Oscillatory Magnetic Field
HOSC
0.1Hz to 1MHz
4000
4500
A/m
Cross-Axis Immunity Multiplier (Note 18)
KX
2.5
VDD1 = 3.3V, VDD2 = 5V
Power Frequency Magnetic Immunity
HPF
50Hz/60Hz
1000
1500
A/m
Pulse Magnetic Field Immunity
HPM
tP = 8µs
1800
2000
A/m
Damped Oscillatory Magnetic Field
HOSC
0.1Hz to 1MHz
1800
2000
A/m
Cross-Axis Immunity Multiplier (Note 18)
FN8860 Rev.4.00
Feb 12, 2018
KX
2.5
Page 6 of 14
ISL32704E
Safety and Approvals
Application Information
VDE V 0884-10
The ISL32704E is an isolated RS-485 transceiver designed for
high-speed data transmission of up to 4Mbps.
Basic Isolation; VDE File Number 5016933-4880-0001/229067
• Working voltage (VIORM) 600VRMS (848VPK); basic insulation,
pollution degree 2
• Transient overvoltage (VIOTM) 4000VPK
• Each part tested at 1590VPK for 1s, 5pC partial discharge limit
• Samples tested at 4000VPK for 60s, then 1358VPK for 10s
with 5pC partial discharge limit
SYMBOL
SAFETY-LIMITING VALUES
VALUE
UNIT
TS
Safety Rating Ambient Temperature
180
°C
PS
Safety Rating Power (180°C)
270
mW
IS
Supply Current Safety Rating (total of
supplies)
54
mA
RS-485 and Isolation
RS-485 is a differential (balanced) data transmission standard for
use in long haul network or noisy environments. It is a true
multipoint standard, which allows up to 32 one-unit load devices
(any combination of drivers and receivers) on a 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 its wide common-mode
range, which specifies that the driver outputs and the receiver
inputs withstand signals ranging from +12V to -7V. This
common-mode range is the sum of the ground potential difference
between driver and receiver, VGPD, the driver output
common-mode offset, VOC, and the longitudinally coupled noise
along the bus lines, Vn: VCM = VGPD + VOC + Vn.
UL 1577
VCC1
Component Recognition Program File Number: E483309
- Working voltage (VIORM) 600VRMS (848VPK); basic
insulation, pollution degree 2
- Transient overvoltage (VIOTM) 4000VPK
- Each part tested at 3000 VRMS (4243VPK) for 1s
- Each lot samples tested at 2500 VRMS (3536VPK) for 60s
VN
D
RT
D
Residential,
Commercial,
and Light
Industrial:
Methods
EN55022,
EN55014
EN50082-2
VGPD
GND1
Immunity to external magnetic fields
is even higher if the field direction is
“end-to-end” rather than “pin-to-pin”
as shown on the right.
FN8860 Rev.4.00
Feb 12, 2018
GND2
FIGURE 3. COMMON-MODE VOLTAGES IN A NON-ISOLATED DATA LINK
However, in networks using isolated transceivers, such as the
ISL32704E, the supply and signal paths of the driver and receiver
bus circuits are galvanically isolated from their local mains
supplies and signal sources.
VCC1
VCC2-ISO
VCC2
VN
ISO
EN50204
Radiated field
Industrial Environment
from digital
EN61000-4-2 (ESD),
EN61000-4-3 (Electromagnetic Field telephones
Immunity)
EN61000-4-4 (EFT)
EN61000-4-6 (RFI Immunity)
EN61000-4-8 (Power Frequency
Magnetic Field immunity)
EN61000-4-9 (Pulsed Magnetic
Field)
EN61000-4-10 (Damped Oscillatory
Magnetic Field)
R
R
VCM
TABLE 1. COMPLIANCE TEST CATEGORIES
EN50081-1
RT
VOC
Electromagnetic Compatibility
The ISL32704E is fully compliant with generic EMC standards
EN50081, EN50082-1, and the umbrella line-voltage standard
for information technology equipment (ITE) EN61000. The
isolator’s Wheatstone bridge configuration and differential
magnetic field signaling ensure excellent EMC performance
against all relevant standards. Compliance tests have been
conducted in the following categories:
VCC2
D
RT
D
RT
R
R
VCM = 0V
RISO
VOC
VCM
GND2-ISO
GND1
VGPD
GND2
FIGURE 4. COMMON-MODE VOLTAGES IN AN ISOLATED DATA LINK
Because the ground potentials of isolated bus nodes are isolated
from each other, the common-mode voltage of one node’s output
has no effect on the bus inputs of another node. This is because
the common-mode voltage is dropping across the
high-resistance isolation barrier of 1014 Ω. Thus, galvanic
isolation extends the maximum allowable common-mode range
of a data link to the maximum working voltage of the isolation
barrier, which for the ISL32704E is 600VRMS.
Page 7 of 14
ISL32704E
Digital Isolator Principle
EXTERNAL B-FIELD
V DD2
INTERNAL
B-FIELD
GMR1
GMR2
GMR3
GMR4
IN
OUT
60
AMPLITUDE (dBµV/m)
The ISL32704E utilizes a giant magneto-resistance (GMR)
isolation. Figure 5 shows the principle operation of a single
channel GMR isolator.
50
FCC-B < 1GHz 3m
40
EN55022 < 1GHz 3m
30
LABORATORY
NOISE FLOOR
20
10
0
10MHz
QpMEASUREMENTS
100MHz
1GHz
FIGURE 7. UNDETECTABLE EMISSIONS OF GMR ISOLATORS
Low EMI Susceptibility
GND 2
FIGURE 5. SINGLE CHANNEL GMR ISOLATOR
The input signal is buffered and drives a primary coil, which
creates a magnetic field that changes the resistance of the GMR
resistors 1 to 4. GMR1 to GMR4 form a Wheatstone bridge in
order to create a bridge output voltage that only reacts to
magnetic field changes from the primary coil. Large external
magnetic fields, however, are treated as common-mode fields
and are therefore suppressed by the bridge configuration. The
bridge output is fed into a comparator whose output signal is
identical in phase and shape to the input signal.
GMR Resistor in Detail
Figure 6 shows a GMR resistor consisting of ferromagnetic alloy
layers, B1, B2, sandwiched around an ultra thin, nonmagnetic
conducting middle layer A, typically copper. The GMR structure is
designed so that, in the absence of a magnetic field, the
magnetic moments in B1 and B2 face opposite directions, thus
causing heavy electron scattering across layer A, which increases
its resistance for current C drastically. When a magnetic field D is
applied, the magnetic moments in B1 and B2 are aligned and
electron scattering is reduced. This lowers the resistance of layer
A and increases current C.
C
HIGH
RESISTANCE
LOW
RESISTANCE
B1
B1
A
B2
C
C
C
A
B2
D
APPLIED
MAGNETIC FIELD
FIGURE 6. MULTI-LAYER GMR RESISTOR
Low Emissions
Because GMR isolators do not use fancy encoding schemes, such
as RF carriers or high-frequency clocks, and do not include power
transfer coils or transformers, their radiated emission spectrum
is virtually undetectable.
FN8860 Rev.4.00
Feb 12, 2018
Because GMR isolators have no pulse trains or carriers to interfere
with, they also have very low EMI susceptibility.
For the list of compliance tests conducted on GMR isolators, refer
to the “Electromagnetic Compatibility” on page 7.
Receiver (Rx) Features
This transceiver utilizes a differential input receiver for maximum
noise immunity and common-mode rejection. Input sensitivity is
±200mV, as required by the RS-485 specification.
The receiver input resistance meets the RS-485 Unit Load (UL)
requirement of 12kΩ minimum. The receiver includes a “fail-safe
if open” function that guarantees a high level receiver output if
the receiver inputs are unconnected (floating). The receiver
output is tri-statable via the active low RE input.
Driver (Tx) Features
The RS-485 driver is a differential output device that delivers at
least 1.5V across a 54Ω purely differential load. The driver
features low propagation delay skew to maximize bit width and
to minimize EMI.
The driver in the ISL32704E is tri-statable via the active high DE
input. The outputs of the ISL32704E driver are not slew rate
limited, so faster output transition times allow data rates of at
least 4Mbps.
Built-In Driver Overload Protection
As stated previously, the RS-485 specification requires that
drivers survive worst-case bus contentions undamaged. The
ISL32704E transmitters meet this requirement via driver output
short-circuit current limits and on-chip thermal shutdown circuitry.
The driver output stage incorporates short-circuit current limiting
circuitry, which ensures that the output current never exceeds the
RS-485 specification. In the event of a major short-circuit
condition, the device also includes a thermal shutdown feature
that disables the driver whenever the die temperature becomes
excessive. This eliminates the power dissipation, allowing the die
to cool. The driver automatically re-enables after the die
temperature drops about 15°C. If the contention persists, the
thermal shutdown/re-enable cycle repeats until the fault is
cleared. The receiver stays operational during thermal shutdown.
Page 8 of 14
ISL32704E
Dynamic Power Consumption
where:
The isolator within the ISL32704E achieves its low power
consumption from the way it transmits data across the barrier.
By detecting the edge transitions of the input logic signal and
converting these to narrow current pulses, a magnetic field is
created around the GMR Wheatstone bridge. Depending on the
direction of the magnetic field, the bridge causes the output
comparator to switch following the input signal. Since the current
pulses are narrow, about 2.5ns, the power consumption is
independent of the mark-to-space ratio and solely depends on
frequency.
• LS is the stub length (ft)
• tr is the driver rise time (s)
• c is the speed of light (9.8 x 108 ft/s)
• v is the signal velocity as a percentage of c.
To ensure the receiver output of the ISL32704E is high when the
bus is not actively driven, fail-safe biasing of the bus lines is
recommended. Figure 8 shows the proper termination of a
high-speed data link with fail-safe biasing.
TABLE 2. SUPPLY CURRENT INCREASE WITH DATA RATE
DATA RATE
(Mbps)
IDD1
(mA)
IDD2
(mA)
1
0.15
0.15
4
0.6
0.6
VS
RB
542R
RT2
135R
RB
542R
Power Supply Decoupling
Both supplies, VDD1 and VDD2, must be bypassed with 100nF
ceramic capacitors. These should be placed as close as possible
to the supply pins for proper operation.
DC CORRECTNESS
The ISL32704E incorporates a patented refresh circuit to maintain
the correct output state with respect to data input. At power-up,
the bus outputs follow the truth tables on page 2. The DE input
should be held low during power-up to prevent false drive data
pulses on the bus. This can be accomplished by connecting a
10kΩ pull-down resistor between DE and GND1.
Data Rate, Cables, and Terminations
RS-485 is intended for network lengths up to 4000 feet, but the
maximum system data rate decreases as the transmission
length increases. Devices operating at 4Mbps are typically
limited to lengths less than 100 feet, but are capable of driving
up to 350 feet of cable when allowing for some jitter of 5%.
Twisted pair is the cable of choice for RS-485 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.
RT1
120R
FIGURE 8. FAIL-SAFE BIASING FOR HIGH-SPEED DATA LINKS
Here the termination resistor value at the cable end without
fail-safe biasing equals the characteristic cable impedance:
RT1 = Z0. The values for RB and RT2 are calculated using
Equations 2 and 3.
VS Z0
R B ----------- -----V AB 4
(EQ. 2)
2R B Z 0
R T2 = -----------------------2R B – Z 0
(EQ. 3)
where:
• RB are the fail-safe biasing resistors
• RT2 is the termination resistor in the fail-safe biasing network
• VS is the minimum transceiver supply voltage
• VAB is the minimum bus voltage of the undriven bus
• Z0 is the characteristic cable impedance
To minimize reflections, proper termination is imperative when
using this high data rate transceiver. 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 for RS-485) at the end farthest from the driver. In
multireceiver applications, stubs connecting receivers 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.
A useful guideline for determining the maximum stub lengths is
given with Equation 1.
Note, the resistor values in Figure 8 have been calculated for
VS = 4.5V, VAB = 0.25V, and Z0 = 120Ω.
tr
L S ------ v c
10
ESD (IEC61000-4-2)
(EQ. 1)
Transient Protection
Protecting the ISL32704E against transients exceeding the
device’s transient immunity requires the addition of an external
TVS. For this purpose, Semtech’s RClamp0512TQ was chosen
due to its high transient protection levels, low junction
capacitance, and small form factor.
TABLE 3. RCLAMP0512 TVS FEATURES
PARAMETER
EFT (IEC61000-4-4)
FN8860 Rev.4.00
Feb 12, 2018
SYMBOL
VALUE
UNIT
Air
VESD
±30
kV
Contact
VESD
±30
kV
VEFT
±4
kV
Page 9 of 14
ISL32704E
TABLE 3. RCLAMP0512 TVS FEATURES (Continued)
PARAMETER
SYMBOL
VALUE
UNIT
Surge (IEC61000-4-5)
VSURGE
±1.3
kV
Junction Capacitance
CJ
3
pF
-
1 x 0.6
mm
Form Factor
The TVS is implemented between the bus lines and isolated
ground (GND2).
Since transient voltages on the bus lines are referenced to Earth
potential, aka Protective Earth (PE), a high-voltage capacitor (CHV)
is inserted between GND2 and PE, providing a low-impedance path
for high-frequency transients.
Note that the connection from the PE point on the isolated side
to the PE point on the non-isolated side (Earth) is usually made
via the metal chassis of the equipment, or via a short, thick wire
of low-inductance.
A high-voltage resistor (RHV) is added in parallel to CHV to prevent
the build-up of static charges on floating grounds (GND2) and
cable shields (typically used in Profibus). The bill of materials for
the circuit in Figure 9 is listed in Table 4.
the GND2 pins between Pins 9 and 15. This allows for increased
layout flexibility.
The wide-body version also provides an isolated DE output,
ISODE, that can be used in PROFIBUS™ applications to monitor
the state of the isolated drive enable node.
The QSOP version (ISL32704EIAZ) is designed for application
flexibility and maximum space saving in dense PCB designs. This
package provides an isolated DE output (ISODE) and a separate
DE input on the bus side (XDE). XDE can be used to enable the
driver from the bus side, or when connected to ISODE, enable the
driver from the DE input on the controller side.
Two separate output supply pins are available, VDD2 for the
isolation module and VDD2X for the transceiver module. Both
pins should be connected externally for normal operation, or can
be used separately for testing and troubleshooting.
The QSOP version also has an “ISOR” output that is isolated from
the receiver output “R” on the controller side. This pin is used for
testing and usually left open, but it could be used for bus-side
monitoring purposes in special circumstances.
Figures 10 and 11 show the typical device connections for both
package versions.
VS-ISO
VS
3.3V ISOLATION 5V
BARRIER
16
1
VDD1
VDD2
100n
9
MCU /
UART
A
ISL32704 10
1
B
2
ISODE 10
SHIELD
TVS
3
GND
5 DE
100n
1.09k
A 12
6 D
127R
PE
CHV
RHV
3 R
B 13
4 RE
PE
GND1
Non-isolated Ground
Protective Earth Ground, Equipment Safety Ground
FIGURE 9. TRANSIENT PROTECTION FOR ISL32704E
FUNCTION
ORDER NO.
170W (8µs, 20µs)
2-LINE PROTECTOR
RCLAMP0512TQ
SEMTECH
CHV
4.7nF, 2kV, 10%
CAPACITOR
1812B472K202NT
NOVACAP
1MΩ, 2kV, 5%
RESISTOR
HVC12061M0JT3
5V
BARRIER
100n
11
16
VDD2X VDD2
ISODE 15
6 D
XDE 12
TT-ELECTRONICS
The wide-body version (ISL32704EIBZ) has a single output power
supply pin, VDD2, supplying the bus side of the isolation module
and the transceiver module.
This package also provides two ground pins for each supply. The
GND1 pins are internally connected between Pins 2 and 8 and
1.09k
A 9
5 DE
Pinout Differences Between Packages
FN8860 Rev.4.00
Feb 12, 2018
3.3V ISOLATION
1
VDD1
VENDOR
TVS
RHV
ISL32704EIBZ
FIGURE 10. TYPICAL WB-SOIC TRANSCEIVER CONNECTIONS
100n
TABLE 4. BOM FOR CIRCUIT IN Figure 9
NAME
9,15
2,8
Isolated Ground, Floating RS-485 Common
1.09k
GND2
127R
2 R
B 10
ISOR 13
4 RE
GND1
GND2
1.09k
14
3
ISL32704EIAZ
FIGURE 11. TYPICAL QSOP TRANSCEIVER CONNECTIONS
Page 10 of 14
ISL32704E
Revision History
The revision history provided is for informational purposes only and is believed to be accurate, but not warranted.
Please visit our website to make sure you have the latest revision.
DATE
REVISION
CHANGE
Feb 12, 2018
FN8860.4 Updated Note 1 and added Note 2.
Updated VDE and UL certification file numbers.
Updated Thermal Information (Theta JA, JC values)
-Changed the 16ld WB-SOIC Package from 60, 12 to 34, 17.
-Changed the 16ld QSOP Package from 60, 10 to 63, 35.
POD M16.3A - updated from rev 0 to rev 1. Changes:
Updated Typical Recommended Land Pattern dimensions lead height from 2.2 to 1.7, lead width from 0.6 to 0.51,
and body center to center from 9.2 to 9.75.
Removed About Intersil section.
Mar 29, 2017
FN8860.3 Added WB-SOIC information throughout document.
Updated Feature bullets
Updated Notes 5 and 6.
Feb 10, 2017
FN8860.2 On page 2, Ordering Information, changed ISL32704EIAZ-EVALZ to ISL32704EVAL1Z.
Jan 19, 2017
FN8860.1 Updated Figure 1 on page 1 and Figure 2 on page 3. Changed from dual to single failsafe biasing.
On page 2, Ordering Information, added ISL32704EIAZ-EVALZ and Note 1 for tape and reel and quantity.
On page 7 in VDE V 0884-11 (Certification Pending) and UL 1577 sections, changed from “Standard” to “Basic”
isolation.
Dec 12, 2016
FN8860.0 Initial Release
FN8860 Rev.4.00
Feb 12, 2018
Page 11 of 14
ISL32704E
Package Outline Drawing
For the most recent package outline drawing, see M16.15B.
M16.15B
16 LEAD QUARTER-SIZE SMALL OUTLINE PLASTIC PACKAGE (QSOP)
Rev 0, 9/16
1
A
3
4.77
5.00
16
5.8
6.2
2
3.8
4.0
9
3
SEE DETAIL "X"
PIN #1
I.D. MARK
45° NOM
1
8
0.635
0.20
0.25
B
TOP VIEW
END VIEW
0.05
H
1.00 REF
1.52
1.75
C
SEATING
PLANE
1.27
1.42
0.10
0.25
0.2
0.3
0.10 C
0.10 MIN
0.25 MAX
5
0.10 M C B A
SIDE VIEW
GAUGE
PLANE
0.25
0° TO 8°
0.50
0.75
DETAIL X
(0.38)
(1.53)
NOTES:
1. Dimension does not include mold flash, protrusions, or gate burrs.
Mold flash, protrusions, or gate burrs shall not exceed 0.15 per side.
2. Dimension does not include interlead flash or protrusion. Interlead
flash or protrusion shall not exceed 0.25 per side.
(5.30)
3. Dimensions are measured at datum plane H.
4. Dimensioning and tolerancing per ASME Y14.5M-1994.
5. Dimension does not include dambar protrusion.
6. Dimension in ( ) are for reference only.
7. Pin spacing is a BASIC dimension; tolerances do not accumulate.
(0.635)
8. Dimensions are in mm.
TYPICAL RECOMMENDED LAND PATTERN
FN8860 Rev.4.00
Feb 12, 2018
Page 12 of 14
ISL32704E
Package Outline Drawing
For the most recent package outline drawing, see M16.3A.
M16.3A
16 LEAD WIDE BODY SMALL OUTLINE PLASTIC PACKAGE (SOICW)
Rev 1, 6/17
10.08
10.49
1
3
0.3
0.5
16
10.00
10.64
2
7.42
7.59
SEE DETAIL "X"
9
6.60
7.11
PIN #1
I.D. MARK
3
1
0.18
0.25
0.85
1.10
8
1.24
1.30
0.2
0.3
TOP VIEW
END VIEW
0.05
H
2.34
2.67
C
2.0
2.5
SEATING
PLANE
0.1
0.3
0.10 C
GAUGE
PLANE
0.25
0.3
5
0.5
0.1 M C B A
0.1 MIN
0.3 MAX
SIDE VIEW
0.40
1.30
0° TO 8°
DETAIL X
(1.7)
NOTES:
1. Dimension does not include mold flash, protrusions, or gate burrs.
Mold flash, protrusions, or gate burrs shall not exceed 0.15 per side.
2. Dimension does not include interlead flash or protrusion. Interlead
flash or protrusion shall not exceed 0.25 per side.
(9.75)
3. Dimensions are measured at datum plane H.
4. Dimensioning and tolerancing per ASME Y14.5M-1994.
5. Dimension does not include dambar protrusion.
6. Dimension in ( ) are for reference only.
7. Pin spacing is a BASIC dimension; tolerances do not accumulate.
8. Dimensions are in mm.
(1.27)
(0.51)
TYPICAL RECOMMENDED LAND PATTERN
FN8860 Rev.4.00
Feb 12, 2018
Page 13 of 14
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