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ISO7420, ISO7420M, ISO7421
SLLS984I – JUNE 2009 – REVISED JULY 2015
ISO742x Low-Power Dual-Channel Digital Isolators
1 Features
3 Description
•
•
The ISO7420, ISO7420M and ISO7421 provide
galvanic isolation up to 2500 VRMS for 1 minute per
UL. These digital isolators have two isolated
channels. Each isolation channel has a logic input
and output buffer separated by a silicon dioxide
(SiO2) insulation barrier. Used in conjunction with
isolated power supplies, these devices prevent noise
currents on a data bus or other circuit from entering
the local ground and interfering with or damaging
sensitive circuitry. The suffix M indicates wide
temperature range (–40°C to 125°C).
1
•
•
•
•
•
•
•
•
•
Highest Signaling Rate: 1 Mbps
Low Power Consumption, Typical ICC per Channel
(3.3-V operation):
– ISO7420: 1.1 mA, ISO7421: 1.5 mA
Low Propagation Delay – 9 ns Typical
Low Skew – 300 ps Typical
Wide TA Range: –40°C to 125°C (M-Grade)
50-kV/μs Transient Immunity, Typical
Over 25-Year Isolation Integrity at Rated Voltage
Operates From 3.3-V and 5-V Supply and Logic
Levels
3.3-V and 5-V Level Translation
Narrow Body SOIC-8 Package
Safety and Regulatory Approvals:
– 4242 VPK Isolation per DIN V VDE V 0884-10
and DIN EN 61010-1
– 2500 VRMS Isolation for 1 minute per UL 1577
– CSA Component Acceptance Notice 5A, IEC
60950-1 and IEC 61010-1 Standards
– CQC Certification per GB4943.1-2011
These devices have TTL input thresholds and require
two supply voltages, 3.3 or 5 V, or any combination.
All inputs are 5-V tolerant when supplied from a 3.3-V
supply.
Note: The ISO7420 and ISO7421 are specified for
signaling rates up to 1 Mbps. Due to their fast
response time, under most cases, these devices will
also transmit data with much shorter pulse widths.
Designers should add external filtering to remove
spurious signals with input pulse duration 175 To 400 .............................................. 15
•
Changed the text of NOTE: ................................................................................................................................................. 16
•
Changed the REGULATORY INFORMATION table ............................................................................................................ 17
Changes from Revision D (July 2010) to Revision E
Page
•
Added new fifth bullet to Features and deleted text from 4-kVpeak bullet item ..................................................................... 1
•
Changed first paragraph in Description from: ISO7420M, ISO7421, and ISO7421M to: ISO7420M and ISO7421 .............. 1
•
Changed ISO742xM in the ELEC CHAR and SWITCHING CHAR table to ISO7420M ........................................................ 8
•
Changed ISO742xM in the ELEC CHAR and SWITCHING CHAR table to ISO7420M ........................................................ 9
•
Changed ISO742xM in the ELEC CHAR and SWITCHING CHAR table to ISO7420M ........................................................ 9
•
Changed ISO742xM in the ELEC CHAR and SWITCHING CHAR table to ISO7420M ...................................................... 10
•
Changed the MAX value in the SWITCHING CHAR table 2nd row from 3.5 to 3.7 and 3rd row from 4 to 4.9................... 10
•
Changed the MAX value in the 2nd SWITCHING CHAR table 2nd row from 4 to 5.6 and 3rd row from 5 to 6.3............... 10
•
Changed the MAX value in the 3rd SWITCHING CHAR table 3rd row from 5 to 8.5 ......................................................... 11
•
Changed the MAX value in the 4rd SWITCHING CHAR table 3rd row from 6 to 6.8 ......................................................... 11
•
Changed Regulatory Information table last row, last column from: pending (E181974) to: E181974 ................................. 17
•
Changed Note 2 in Function Table from: ISO7420M, ISO7421, and ISO7421M to: ISO7420M and ISO7421................... 17
Changes from Revision C (March 2010) to Revision D
Page
•
Updated the Features List ...................................................................................................................................................... 1
•
Deleted devices ISO7420F and ISO7420FM from the data sheet......................................................................................... 1
•
Updated the device Description. Add paragraph - Note: The ISO7420 and ISO7421........................................................... 1
•
Added Tstg to the Absolute Maximum Ratings Table ............................................................................................................ 7
•
Updated the Recommended Operating Conditions table....................................................................................................... 7
•
Updates throughout the Electrical Characteristics and Switching Characteristics tables ...................................................... 8
•
Updated the Supply Current test conditions........................................................................................................................... 8
•
Deleted the SUPPLY CURRENT vs SIGNAL RATE (ALL CHANNELS) graphs and the EYE DIAGRAM plots ................. 12
•
Changed Figure 7................................................................................................................................................................. 13
•
Changed the VIORM, VPR, and VIOTM unit values From: V To: Vpeak .................................................................................... 15
•
Changed Minimum internal gap MIN value From: 0.008 To: 0.014mm ............................................................................... 15
•
Changed the Barrier capacitance, input to output test conditions........................................................................................ 15
•
Changed the Input capacitance test conditions ................................................................................................................... 15
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Changed VI From: 5.5 V To: 5.25 V ..................................................................................................................................... 16
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Changed From: 107mA To: 112mA...................................................................................................................................... 16
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Changed VI From: 3.6 V To: 3.45 V ..................................................................................................................................... 16
•
Changed From: 164mA To: 171mA...................................................................................................................................... 16
•
Changed Figure 10............................................................................................................................................................... 16
•
Deleted the ICC equations section......................................................................................................................................... 16
•
Changed the Function Table Output values for PU (Open) From: H/L To: H ...................................................................... 17
•
Changed Figure 11............................................................................................................................................................... 17
Copyright © 2009–2015, Texas Instruments Incorporated
Product Folder Links: ISO7420 ISO7420M ISO7421
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ISO7420, ISO7420M, ISO7421
SLLS984I – JUNE 2009 – REVISED JULY 2015
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Changes from Revision B (February 2010) to Revision C
Page
•
Added devices ISO7420F and ISO7420FM to the data sheet ............................................................................................... 1
•
Added The suffix M indicates wide temperature range (–55°C to 125°C) and the suffix F indicates output-low option
in fail-safe condition. All other devices without the F suffix default to output-high in fail-safe state. ..................................... 1
•
Added ISO7420F and ISO7420FM to the Available Options Table ....................................................................................... 6
•
Changed value from a max of 4 mA to a min of –4 mA ......................................................................................................... 7
•
Changed value from a min of –4 mA to a max of 4 mA ........................................................................................................ 7
•
Changed Electrical Characteristics Conditions....................................................................................................................... 8
•
Deleted Ci from the ELECTRICAL CHARACTERISTICS....................................................................................................... 8
•
Added (All inputs switching with square wave clock signal for dynamic ICC measurement)................................................. 8
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Changed ELECTRICAL CHARACTERISTICS conditions...................................................................................................... 9
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Added High-level output voltage ISO7420 / 7421 (3.3-V side) test condition ....................................................................... 9
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Changed High-level output voltage min value........................................................................................................................ 9
•
Deleted CI specification .......................................................................................................................................................... 9
•
Added (All inputs switching with square wave clock signal for dynamic ICC measurement)................................................. 9
•
Changed ELECTRICAL CHARACTERISTICS conditions...................................................................................................... 9
•
Added High-level output voltage ISO7420 / 7421 (5-V side) test condition ........................................................................... 9
•
Changed High-level output voltage min value........................................................................................................................ 9
•
Deleted CI specification .......................................................................................................................................................... 9
•
Added (All inputs switching with square wave clock signal for dynamic ICC measurement)................................................. 9
•
Changed ELECTRICAL CHARACTERISTICS conditions.................................................................................................... 10
•
Deleted CI specification ........................................................................................................................................................ 10
•
Added (All inputs switching with square wave clock signal for dynamic ICC measurement)............................................... 10
•
Changed SWITCHING CHARACTERISTICS conditions ..................................................................................................... 10
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Changed PWD parameter from duration to width ................................................................................................................ 10
•
Changed Switching Characteristics conditions..................................................................................................................... 10
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Changed Pulse duration distortion to Pulse width distortion ............................................................................................... 10
•
Changed Switching Characteristics conditions..................................................................................................................... 11
•
Changed SWITCHING CHARACTERISTICS conditions ..................................................................................................... 11
•
Changed Pulse duration distortion to Pulse width distortion ............................................................................................... 11
•
Changed SWITCHING CHARACTERISTICS conditions ..................................................................................................... 11
•
Changed Pulse duration distortion to Pulse width distortion ................................................................................................ 11
•
Changed Figure 7................................................................................................................................................................. 13
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Added input to output and note 1 to Isolation resistance, input to output ............................................................................ 15
•
Changed the Isolation resistance test conditions ................................................................................................................. 15
•
Changed the Isolation resistance test conditions ................................................................................................................. 15
•
Added note 1 to Barrier capacitance, input to output ........................................................................................................... 15
•
Added Input capacitance ...................................................................................................................................................... 15
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Changed TJ = 170°C to TJ = 150°C...................................................................................................................................... 16
•
Changed From: 124mA To: 107mA...................................................................................................................................... 16
•
Changed TJ = 170°C to TJ = 150°C...................................................................................................................................... 16
•
Changed From: 190mA To: 164mA...................................................................................................................................... 16
•
Changed Figure 10............................................................................................................................................................... 16
•
Changed the Function Table Output values for PU (Open) From: H To: H/L ...................................................................... 17
•
Changed the Function Table Output values for PU (X) From: H To: H/L............................................................................. 17
•
Changed the Function Table Output values for PU (X) From: H/L To: H............................................................................. 17
4
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Copyright © 2009–2015, Texas Instruments Incorporated
Product Folder Links: ISO7420 ISO7420M ISO7421
ISO7420, ISO7420M, ISO7421
www.ti.com
SLLS984I – JUNE 2009 – REVISED JULY 2015
•
Added Note (2) in the Function Table .................................................................................................................................. 17
•
Changed Figure 11............................................................................................................................................................... 17
Changes from Revision A (December 2009) to Revision B
•
Page
Switching Characteristics Table, Added Note (2) - Typical specifications are measured at ideal conditions of 25°C.
Max or Min specifications are measured at worst case conditions for VCC and temperature. ............................................... 8
Changes from Original (June 2009) to Revision A
Page
•
Added devices ISO7420 and ISO7420M to the data sheet ................................................................................................... 1
•
Added the ICC equations section........................................................................................................................................... 16
Copyright © 2009–2015, Texas Instruments Incorporated
Product Folder Links: ISO7420 ISO7420M ISO7421
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ISO7420, ISO7420M, ISO7421
SLLS984I – JUNE 2009 – REVISED JULY 2015
www.ti.com
5 Pin Configuration and Functions
1
INA
2
INB
3
GND1
4
ISO7421: D Package
8-Pin SOIC
(Top View)
8
VCC2
7
OUTA
6
OUTB
5
GND2
VCC1
1
OUTA
2
INB
3
GND1
4
Isolation
VCC1
Isolation
ISO7420: D Package
8-Pin SOIC
(Top View)
8
VCC2
7
INA
6
OUTB
5
GND2
Pin Functions
PIN
I/O
DESCRIPTION
NAME
ISO7420
ISO7421
GND1
4
4
—
Ground connection for VCC1
GND2
5
5
—
Ground connection for VCC2
INA
2
7
I
Input, channel A
INB
3
3
I
Input, channel B
OUTA
7
2
O
Output, channel A
OUTB
6
6
O
Output, channel B
VCC1
1
1
—
Power supply, VCC1
VCC2
8
8
—
Power supply, VCC2
6
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Product Folder Links: ISO7420 ISO7420M ISO7421
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SLLS984I – JUNE 2009 – REVISED JULY 2015
6 Specifications
6.1 Absolute Maximum Ratings
(1)
See
MIN
MAX
UNIT
VCC
Supply voltage (2), VCC1, VCC2
–0.5
6
V
VI
Voltage at IN, OUT
–0.5
VCC + 0.5 (3)
V
IO
Output current
–15
15
mA
TJ(max)
Maximum junction temperature
150
°C
Tstg
Storage temperature
150
°C
(1)
(2)
(3)
–65
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only and functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating
Conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
All voltage values except differential I/O bus voltages are with respect to network ground terminal and are peak voltage values.
Maximum voltage must not exceed 6 V.
6.2 ESD Ratings
VALUE
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001
V(ESD)
(1)
Electrostatic discharge
(1)
UNIT
±4000
Field-induced charged-device model, JEDEC Standard 22, Test Method
C101
±1500
Machine model, ANSI/ESDS5.2-1996
±200
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions
MIN NOM MAX
UNIT
VCC1,
VCC2
Supply voltage - 3.3-V operation
3.15
3.3
3.45
Supply voltage - 5-V operation
4.75
5
5.25
IOH
High-level output current
IOL
Low-level output current
VIH
High-level input voltage
2
5.25
V
VIL
Low-level input voltage
0
0.8
V
1/tui
Signaling rate
0
1
tui
Input pulse duration
1
TJ (1)
Junction temperature
TA
Ambient temperature
(1)
–4
V
mA
4
mA
Mbps
us
–40
136
ISO7420, ISO7421
-40
25
105
ISO7420M
-40
25
125
°C
°C
To maintain the recommended operating conditions for TJ, see the Thermal Information.
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ISO7420, ISO7420M, ISO7421
SLLS984I – JUNE 2009 – REVISED JULY 2015
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6.4 Thermal Information
ISO742x
THERMAL METRIC (1)
D (SOIC)
UNIT
8 PINS
Low-K Board
212
High-K Board
116.6
RθJA
Junction-to-ambient thermal resistance
RθJC(top)
Junction-to-case (top) thermal resistance
71.6
°C/W
RθJB
Junction-to-board thermal resistance
57.3
°C/W
ψJT
Junction-to-top characterization parameter
28.3
°C/W
ψJB
Junction-to-board characterization parameter
56.8
°C/W
(1)
°C/W
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report, SPRA953.
6.5 Electrical Characteristics: VCC1 and VCC2 at 5 V ±5%
TA = –40°C to 125°C for ISO7420M, TA = –40°C to 105°C for ISO742x
PARAMETER
VOH
High-level output voltage
VOL
Low-level output voltage
MIN
TYP
IOH = –4 mA; see Figure 6.
TEST CONDITIONS
VCCO (1) – 0.8
4.6
IOH = –20 μA; see Figure 6.
VCCO – 0.1
5
High-level input current
IIL
Low-level input current
0.2
0.4
IOL = 20 μA; see Figure 6.
0
0.1
CMTI
Common-mode transient immunity
400
INx at 0 V or VCCI
25
μA
μA
–10
VI = VCCI or 0 V; see Figure 8.
V
mV
10
(1)
UNIT
V
IOL = 4 mA; see Figure 6.
VI(HYS) Input threshold voltage hysteresis
IIH
MAX
50
kV/μs
SUPPLY CURRENT (ALL INPUTS SWITCHING WITH SQUARE WAVE CLOCK SIGNAL FOR DYNAMIC ICC MEASUREMENT)
ISO7420
ICC1
Supply current for VCC1
ICC2
Supply current for VCC2
DC to 1 Mbps VI = VCCI or 0 V, 15 pF load
0.4
1
3
6
2
4
2
4
mA
ISO7421
ICC1
Supply current for VCC1
ICC2
Supply current for VCC2
(1)
8
DC to 1 Mbps VI = VCCI or 0 V, 15 pF load
mA
VCCI = Input-side power supply, VCCO = Output-side power supply
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SLLS984I – JUNE 2009 – REVISED JULY 2015
6.6 Electrical Characteristics: VCC1 at 5 V ±5%, VCC2 at 3.3 V ±5%
TA = –40°C to 125°C for ISO7420M, TA = –40°C to 105°C for ISO742x
PARAMETER
TEST CONDITIONS
IOH = –4 mA;
see Figure 6.
VOH
High-level output voltage
ISO7421 (5-V side)
ISO7420 / 7421 (3.3-V side).
IOH = –20 μA; see Figure 6,
VOL
Low-level output voltage
VI(HYS)
Input threshold voltage hysteresis
IIH
High-level input current
IIL
Low-level input current
CMTI
Common-mode transient immunity
MIN
VCCO
(1)
TYP
–
0.8
4.6
VCCO – 0.4
3
VCCO – 0.1
VCC
MAX
V
IOL = 4 mA; see Figure 6.
0.2
0.4
IOL = 20 μA; see Figure 6.
0
0.1
400
INx at 0 V or VCCI
VI = VCCI or 0 V; seeFigure 8 .
μA
μA
–10
25
V
mV
10
(1)
UNIT
40
kV/μs
SUPPLY CURRENT (ALL INPUTS SWITCHING WITH SQUARE WAVE CLOCK SIGNAL FOR DYNAMIC ICC MEASUREMENT)
ISO7420
ICC1
Supply current for VCC1
ICC2
Supply current for VCC2
DC to 1 Mbps VI = VCCI or 0 V, 15 pF load
0.4
1
mA
2
4.5
mA
ISO7421
ICC1
Supply current for VCC1
ICC2
Supply current for VCC2
(1)
DC to 1 Mbps VI = VCCI or 0 V, 15 pF load
2
4
mA
1.5
3.5
mA
MAX
VCCI = Input-side power supply, VCCO = Output-side power supply
6.7 Electrical Characteristics: VCC1 at 3.3 V ±5%, VCC2 at 5 V ±5%
TA = –40°C to 125°C for ISO7420M, TA = –40°C to 105°C for ISO742x
PARAMETER
TEST CONDITIONS
IOH = –4 mA;
see Figure 6.
VOH
High-level output voltage
ISO7420 / 7421 (5-V side).
ISO7421 (3.3-V side)
IOH = –20 μA; see Figure 6
VOL
Low-level output voltage
VI(HYS)
Input threshold voltage hysteresis
IIH
High-level input current
IIL
Low-level input current
CMTI
Common-mode transient immunity
MIN
TYP
VCCO (1) –
0.8
4.6
VCCO – 0.4
3
VCCO – 0.1
VCC
V
IOL = 4 mA; see Figure 6.
0.2
0.4
IOL = 20 μA; see Figure 6.
0
0.1
400
INx at 0 V or VCCI (1)
VI = VCCI or 0 V; see Figure 8.
V
mV
10
μA
μA
–10
25
UNIT
40
kV/μs
SUPPLY CURRENT (ALL INPUTS SWITCHING WITH SQUARE WAVE CLOCK SIGNAL FOR DYNAMIC ICC MEASUREMENT)
ISO7420
ICC1
Supply current for VCC1
ICC2
Supply current for VCC2
DC to 1 Mbps
VI = VCCI or 0 V, 15 pF load
DC to 1 Mbps
VI = VCCI or 0 V, 15 pF load
0.2
0.7
3
6
1.5
3.5
2
4
mA
ISO7421
ICC1
Supply current for VCC1
ICC2
Supply current for VCC2
(1)
mA
VCCI = Input-side power supply, VCCO = Output-side power supply
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6.8 Electrical Characteristics: VCC1 and VCC2 at 3.3 V ±5%
TA = –40°C to 125°C for ISO7420M, TA = –40°C to 105°C for ISO742x
PARAMETER
TEST CONDITIONS
VOH
High-level output voltage
VOL
Low-level output voltage
MIN
IOH = –4 mA; see Figure 6.
VCCO
IOH = –20 μA; see Figure 6.
(1)
– 0.4
3
VCCO – 0.1
3.3
High-level input current
IIL
Low-level input current
CMTI
Common-mode transient
immunity
MAX
0.2
0.4
IOL = 20 μA; see Figure 6.
0
0.1
400
μA
μA
–10
VI = VCCI or 0 V; seeFigure 8 .
V
mV
10
INx at 0 V or VCCI (1)
UNIT
V
IOL = 4 mA; see Figure 6.
VI(HYS) Input threshold voltage hysteresis
IIH
TYP
25
40
kV/μs
SUPPLY CURRENT (ALL INPUTS SWITCHING WITH SQUARE WAVE CLOCK SIGNAL FOR DYNAMIC ICC MEASUREMENT)
ISO7420
ICC1
Supply current for VCC1
ICC2
Supply current for VCC2
DC to 1 Mbps
VI = VCCI or 0 V, 15 pF load
DC to 1 Mbps
VI = VCCI or 0 V, 15 pF load
0.2
0.7
2
4.5
1.5
3.5
1.5
3.5
mA
ISO7421
ICC1
Supply current for VCC1
ICC2
Supply current for VCC2
(1)
mA
VCCI = Input-side power supply, VCCO = Output-side power supply
6.9 Power Dissipation Characteristics
ISO742x
THERMAL METRIC
D (SOIC)
UNIT
8 PINS
PD
VCC1 = VCC2 = 5.25 V, TJ = 150°C, CL = 15 pF
Input a 1-Mbps 50% duty-cycle square wave
Device power dissipation
55
mW
6.10 Switching Characteristics: VCC1 and VCC2 at 5 V ±5%
TA = –40°C to 125°C for ISO7420M, TA = –40°C to 105°C for ISO742x
PARAMETER
tPLH, tPHL
PWD
(1)
TEST CONDITIONS
Propagation delay time
MIN
See Figure 6.
MAX
9
14
UNIT
ns
0.3
3.7
ns
tsk(pp)
Part-to-part skew time
4.9
ns
tsk(o)
Channel-to-channel output skew time
3.6
ns
tr
Output signal rise time
tf
Output signal fall time
tfs
Fail-safe output delay time from input power loss
(1)
Pulse width distortion |tPHL – tPLH|
TYP
See Figure 6.
1
See Figure 7.
ns
1
ns
6
μs
Also known as pulse skew.
6.11 Switching Characteristics: VCC1 at 5 V ±5%, VCC2 at 3.3 V ±5%
TA = –40°C to 125°C for ISO7420M, TA = –40°C to 105°C for ISO742x
PARAMETER
TEST CONDITIONS
tPLH, tPHL
Propagation delay time
PWD (1)
Pulse width distortion |tPHL – tPLH|
tsk(pp)
Part-to-part skew time
tsk(o)
Channel-to-channel output skew time
tr
Output signal rise time
(1)
10
See Figure 6.
See Figure 6.
MIN
TYP
MAX
10
17
ns
0.5
5.6
ns
6.3
ns
4
ns
2
UNIT
ns
Also known as pulse skew.
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Switching Characteristics: VCC1 at 5 V ±5%, VCC2 at 3.3 V ±5% (continued)
TA = –40°C to 125°C for ISO7420M, TA = –40°C to 105°C for ISO742x
PARAMETER
TEST CONDITIONS
tf
Output signal fall time
tfs
Fail-safe output delay time from input power loss
MIN
See Figure 7.
TYP
MAX
UNIT
2
ns
6
μs
6.12 Switching Characteristics: VCC1 at 3.3 V ±5%, VCC2 at 5 V ±5%
TA = –40°C to 125°C for ISO7420M, TA = –40°C to 105°C for ISO742x
PARAMETER
tPLH, tPHL
PWD
(1)
TEST CONDITIONS
Propagation delay time
Pulse width distortion |tPHL – tPLH|
tsk(pp)
Part-to-part skew time
tsk(o)
Channel-to-channel output skew time
tr
Output signal rise time
tf
Output signal fall time
tfs
Fail-safe output delay time from input power loss
(1)
MIN
See Figure 6.
TYP
MAX
10
17
ns
0.5
See Figure 6.
UNIT
4
ns
8.5
ns
4
ns
2
See Figure 7.
ns
2
ns
6
μs
Also known as pulse skew.
6.13 Switching Characteristics: VCC1 and VCC2 at 3.3 V ±5%
TA = –40°C to 125°C for ISO7420M, TA = –40°C to 105°C for ISO742x
PARAMETER
TEST CONDITIONS
tPLH, tPHL
Propagation delay time
PWD (1)
Pulse width distortion |tPHL – tPLH|
tsk(pp)
Part-to-part skew time
tsk(o)
Channel-to-channel output skew time
tr
Output signal rise time
tf
Output signal fall time
tfs
Fail-safe output delay time from input power loss
(1)
See Figure 6.
See Figure 6.
See Figure 7.
MIN
TYP
MAX
UNIT
12
20
ns
1
5
ns
6.8
ns
5.5
ns
2
ns
2
ns
6
μs
Also known as pulse skew.
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6.14 Typical Characteristics
1.6
12
Input Voltage Switching Threshold − V
tpd − Propagation Delay Time − ns
14
VCC1, VCC2 at 3.3 V
10
8
VCC1, VCC2 at 5 V
6
4
2
0
−55
−35
−15
5
25
45
65
85
105
TA − Free-Air Temperature − °C
1.1
VIT−, 5 V
1.0
VIT−, 3.3 V
0.9
−35
−15
5
25
45
65
85
105
TA − Free-Air Temperature − °C
IOH − High-Level Output Current − mA
Fail-Safe Voltage Threshold − V
1.2
125
G005
Figure 2. Input Voltage Switching Threshold vs Free-Air
Temperature
2.61
FS+
2.59
2.58
2.57
2.56
FS−
2.54
2.53
2.52
−55
VIT+, 3.3 V
1.3
G004
2.62
2.55
1.4
0.8
−55
125
Figure 1. Propagation Delay Time vs Free-Air Temperature
2.60
VIT+, 5 V
1.5
0
TA = 25°C
−10
−20
−30
−40
VCC1, VCC2 at 3.3 V
−50
−60
−70
VCC1, VCC2 at 5 V
−80
−90
−35
−15
5
25
45
65
85
105
TA − Free-Air Temperature − °C
0
125
1
2
3
4
VOH − High-Level Output Voltage − V
G006
Figure 3. Fail-Safe Voltage Threshold vs Free-Air
Temperature
5
6
G007
Figure 4. High-Level Output Current vs High-Level Output
Voltage
IOL − Low-Level Output Current − mA
80
TA = 25°C
70
60
VCC1, VCC2 at 5 V
50
40
VCC1, VCC2 at 3.3 V
30
20
10
0
0
1
2
3
4
5
6
VOL − Low-Level Output Voltage − V
G008
Figure 5. Low-Level Output Current vs Low-Level Output Voltage
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Isolation Barrier
7 Parameter Measurement Information
IN
Input
Generator
50 W
VI
(1)
VCCI
VI
OUT
1.4 V
1.4 V
0V
VO
CL
tPLH
(2)
tPHL
90%
10%
50%
VO
50%
VOH
VOL
tr
tf
(1)
The input pulse is supplied by a generator having the following characteristics: PRR ≤ 50 kHz, 50% duty cycle,
tr ≤ 3 ns, tf ≤ 3 ns, ZO = 50 Ω. At the input, a 50-Ω resistor is required to terminate the Input Generator signal. It is not
needed in actual application.
(2)
CL = 15 pF and includes instrumentation and fixture capacitance within ±20%.
Figure 6. Switching Characteristic Test Circuit and Voltage Waveforms
VI
VCCI
VCCI
(1)
Isolation Barrier
IN = 0 V
VI
2.7 V
0V
OUT
tfs
VO
VOH
CL
50%
VO
(1)
Fail-Safe HIGH
VOL
CL = 15 pF ± 20% includes instrumentation and fixture capacitance.
Figure 7. Fail-Safe Output Delay-Time Test Circuit and Voltage Waveforms
S1
IN
C = 0.1 μ F ±1%
Isolation Barrier
VCCI
VCCO
C = 0.1 μ F ±1%
Pass-fail criteria –
output must remain
stable.
OUT
+
CL
(1)
GNDI
VOH or VOL
GNDO
–
+ VCM –
(1)
CL = 15 pF and includes instrumentation and fixture capacitance within ±20%.
Figure 8. Common-Mode Transient Immunity Test Circuit
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8 Detailed Description
8.1 Overview
The isolator in Figure 9 is based on a capacitive isolation barrier technique. The I/O channel of the device
consists of two internal data channels, a high-frequency channel (HF) with a bandwidth from 100 kbps up to
1 Mbps, and a low-frequency channel (LF) covering the range from 100 kbps down to DC. In principle, a
single- ended input signal entering the HF-channel is split into a differential signal via the inverter gate at the
input. The following capacitor-resistor networks differentiate the signal into transients, which then are
converted into differential pulses by two comparators. The comparator outputs drive a NOR-gate flip-flop
whose output feeds an output multiplexer. A decision logic (DCL) at the driving output of the flip-flop
measures the durations between signal transients. If the duration between two consecutive transients
exceeds a certain time limit, (as in the case of a low-frequency signal), the DCL forces the output-multiplexer
to switch from the high- to the low-frequency channel.
Because low-frequency input signals require the internal capacitors to assume prohibitively large values,
these signals are pulse-width modulated (PWM) with the carrier frequency of an internal oscillator, thus
creating a sufficiently high frequency signal, capable of passing the capacitive barrier. As the input is
modulated, a low-pass filter (LPF) is needed to remove the high-frequency carrier from the actual data before
passing it on to the output multiplexer.
8.2 Functional Block Diagram
Figure 9. Conceptual Block Diagram of a Digital Capacitive Isolator
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8.3 Feature Description
8.3.1 Insulation Characteristics
over recommended operating conditions (unless otherwise noted)
PARAMETER (1)
TEST CONDITIONS
SPECIFICATION
UNIT
DIN V VDE V 0884-10 (VDE V 0884-10):2006-12
VIORM
Maximum working insulation voltage
VPR
Input-to-output test voltage
VIOTM
Transient overvoltage
RS
Insulation resistance
t = 1 s (100% production), partial discharge 5 pC
t = 60 s (qualification)
t = 1 s (100% production)
VIO = 500 V at TS
566
VPK
1062
VPK
4242
VPK
>109
Ω
Pollution degree
2
UL 1577
VISO
(1)
VTEST = VISO = 2500 VRMS, t = 60 s (qualification)
VTEST = 1.2 x VISO = 3000 VRMS, t = 1 s (100%
production)
Isolation voltage per UL
2500
VRMS
Climatic Classification 40/125/21
Table 1. IEC 60664-1 Ratings Table
PARAMETER
TEST CONDITIONS
SPECIFICATION
Material group
II
Installation classification
Rated mains voltage ≤ 150 VRMS
I–IV
Rated mains voltage ≤ 300 VRMS
I–III
8.3.2 Package Characteristics
over recommended operating conditions (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
L(I01)
Minimum air gap (clearance)
Shortest terminal-to-terminal distance through air
4
mm
L(I02)
Minimum external tracking
(creepage)
Shortest terminal-to-terminal distance across the
package surface
4
mm
CTI
Tracking resistance (comparative
tracking index)
DIN EN 60112 (VDE 0303-11); IEC 60112
>400
DTI
Distance through the insulation
Minimum internal gap (internal clearance)
0.014
V
mm
VIO = 500 V, TA = 25°C
12
>10
Ω
VIO = 500 V, 100°C ≤ TA ≤ max
>1011
Ω
RIO
Isolation resistance, input to
output (1)
CIO
Barrier capacitance, input to
output (1)
VIO = 0.4 sin (2πft), f = 1 MHz
1
pF
CI
Input capacitance (2)
VI = VCC/2 + 0.4 sin (2πft), f = 1 MHz, VCC = 5 V
1
pF
(1)
(2)
All pins on each side of the barrier tied together creating a two-terminal device.
Measured from input pin to ground.
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SPACER
NOTE
Creepage and clearance requirements should be applied according to the specific
equipment isolation standards of an application. Care should be taken to maintain the
creepage and clearance distance of a board design to ensure that the mounting pads of
the isolator on the printed-circuit board do not reduce this distance.
Creepage and clearance on a printed-circuit board become equal in certain cases.
Techniques such as inserting grooves and/or ribs on a printed circuit board are used to
help increase these specifications.
8.3.3 Safety Limiting Values
Safety limiting intends to prevent potential damage to the isolation barrier upon failure of input or output circuitry. A failure of
the I/O can allow low resistance to ground or the supply and, without current limiting, dissipate sufficient power to overheat
the die and damage the isolation barrier, potentially leading to secondary system failures.
PARAMETER
TEST CONDITIONS
IS
Safety input, output, or supply
current
TS
Maximum safety temperature
MIN
TYP
MAX
θJA = 212°C/W, VI = 5.25 V, TJ = 150°C, TA = 25°C
112
θJA = 212°C/W, VI = 3.45 V, TJ = 150°C, TA = 25°C
171
150
UNIT
mA
°C
The safety-limiting constraint is the absolute-maximum junction temperature specified in the Absolute Maximum
Ratings table. The power dissipation and junction-to-air thermal impedance of the device installed in the
application hardware determines the junction temperature. The assumed junction-to-air thermal resistance in the
Thermal Information table is that of a device installed in the JESD51-3, Low-Effective-Thermal-Conductivity Test
Board for Leaded Surface-Mount Packages and is conservative. The power is the recommended maximum input
voltage times the current. The junction temperature is then the ambient temperature plus the power times the
junction-to-air thermal resistance.
Safety Limiting Current − mA
180
VCC1, VCC2 at 3.45 V
160
140
120
100
VCC1, VCC2 at 5.25 V
80
60
40
20
0
0
50
100
150
200
Case Temperature − °C
G002
Figure 10. θJC Thermal Derating Curve per VDE
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8.3.4 Regulatory Information
VDE
CSA
UL
Certified according to
DIN V VDE V 0884-10 (VDE V
0884-10):2006-12 and
DIN EN 61010-1 (VDE 0411-1):
2011-07
Approved under CSA Component
Acceptance Notice #5A
Basic Insulation
Maximum Transient Overvoltage,
4242 VPK
Maximum Working Voltage, 566
VPK
Certificate number: 40016131
(1)
CQC
Recognized under UL1577
Component Recognition
Program (1)
Certified according to
GB4943.1-2011
Basic insulation per CSA 60950-107 and IEC 60950-1 (2nd Ed),
390 VRMS maximum working
voltage
Single Protection, 2500 VRMS
Basic Insulation, Altitude ≤
5000 m, Tropical Climate, 250
VRMS maximum working
voltage
Master contract number: 220991
File number: E181974
Certificate number:
CQC14001109540
Production tested ≥ 3000 VRMS for 1 second in accordance with UL 1577.
8.4 Device Functional Modes
Table 2. Function Table (1)
(1)
(2)
VCCI
VCCO
PU
PU
INPUT
INA, INB
OUTPUT
OUTA, OUTB
H
H
L
L
Open
H (2)
PD
PU
X
H (2)
X
PD
X
Undetermined
VCCI = Input-side power supply; VCCO = Output-side power supply;
PU = Powered up (VCC ≥ 3.15 V); PD = Powered down (VCC ≤ 2.1
V); X = Irrelevant; H = High level; L = Low level
In fail-safe condition, output defaults to high level.
8.4.1 Device I/O Schematics
Input
VCCI
VCCI
VCCI
Output
VCCO
1 MW
8W
500 W
IN
OUT
13 W
Figure 11. Device I/O Schematics
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9 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
9.1 Application Information
ISO742x utilize single-ended TTL-logic switching technology. Its supply voltage range is from 3.15 V to 5.25 V for
both supplies, VCC1 and VCC2. When designing with digital isolators, it is important to keep in mind that due to the
single-ended design structure, digital isolators do not conform to any specific interface standard and are only
intended for isolating single-ended CMOS or TTL digital signal lines. The isolator is typically placed between the
data controller (i.e. μC or UART), and a data converter or a line transceiver, regardless of the interface type or
standard.
9.2 Typical Application
ISO7421 can be used with Texas Instruments' mixed signal micro-controller, digital-to-analog converter,
transformer driver, and voltage regulator to create an isolated 4-20 mA current loop.
VCC1
VCC2
ISO7421
Figure 12. Isolated 4-20 mA Current Loop
9.2.1 Design Requirements
Unlike optocouplers, which require external components to improve performance, provide bias, or limit current,
the ISO742x only require two external bypass capacitors to operate.
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Typical Application (continued)
9.2.2 Detailed Design Procedure
ISO7420
VCC1
8
1
VCC2
0.1 µF
0.1 µF
INA
2
7
OUTA
INB
3
6
OUTB
GND1
4
5
GND2
ISO7421
VCC1
1
8
VCC2
0.1 µF
0.1 µF
OUTA
2
7
INA
INB
3
6
OUTB
GND1
4
5
GND2
Figure 13. Typical ISO7420 and ISO7421 Circuit Hookup
9.2.3 Application Curve
Life Expectancy – Years
100
VIORM at 566 V
28 Years
10
0
120
250
500
750
880
1000
VIORM – Working Voltage – V
G001
Figure 14. Life Expectancy vs Working Voltage
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10 Power Supply Recommendations
To ensure reliable operation at all data rates and supply voltages, a 0.1 µF bypass capacitor is recommended at
input and output supply pins (VCC1 and VCC2). The capacitors should be placed as close to the supply pins as
possible. If only a single primary-side power supply is available in an application, isolated power can be
generated for the secondary-side with the help of a transformer driver such as Texas Instruments' SN6501. For
such applications, detailed power supply design and transformer selection recommendations are available in
SN6501 datasheet (SLLSEA0).
11 Layout
11.1 Layout Guidelines
A minimum of four layers is required to accomplish a low EMI PCB design (see Figure 15). Layer stacking should
be in the following order (top-to-bottom): high-speed signal layer, ground plane, power plane and low-frequency
signal layer.
• Routing the high-speed traces on the top layer avoids the use of vias (and the introduction of their
inductances) and allows for clean interconnects between the isolator and the transmitter and receiver circuits
of the data link.
• Placing a solid ground plane next to the high-speed signal layer establishes controlled impedance for
transmission line interconnects and provides an excellent low-inductance path for the return current flow.
• Placing the power plane next to the ground plane creates additional high-frequency bypass capacitance of
approximately 100pF/in2.
• Routing the slower speed control signals on the bottom layer allows for greater flexibility as these signal links
usually have margin to tolerate discontinuities such as vias.
If an additional supply voltage plane or signal layer is needed, add a second power / ground plane system to the
stack to keep it symmetrical. This makes the stack mechanically stable and prevents it from warping. Also the
power and ground plane of each power system can be placed closer together, thus increasing the high-frequency
bypass capacitance significantly.
For detailed layout recommendations, see Application Note Digital Isolator Design Guide, SLLA284.
11.1.1 PCB Material
For digital circuit boards operating below 150 Mbps, (or rise and fall times higher than 1 ns), and trace lengths of
up to 10 inches, use standard FR-4 epoxy-glass as PCB material. FR-4 (Flame Retardant 4) meets the
requirements of Underwriters Laboratories UL94-V0, and is preferred over cheaper alternatives due to its lower
dielectric losses at high frequencies, less moisture absorption, greater strength and stiffness, and its selfextinguishing flammability-characteristics.
11.2 Layout Example
High-speed traces
10 mils
Ground plane
40 mils
Keep this
space free
from planes,
traces , pads,
and vias
FR-4
0r ~ 4.5
Power plane
10 mils
Low-speed traces
Figure 15. Recommended Layer Stack
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12 Device and Documentation Support
12.1 Documentation Support
12.1.1 Related Documentation
For related documentation, see the following:
• SN6501 Transformer Driver for Isolated Power Supplies, SLLSEA0
• Isolation Glossary, SLLA353
• Digital Isolator Design Guide, SLLA284
12.2 Related Links
The table below lists quick access links. Categories include technical documents, support and community
resources, tools and software, and quick access to sample or buy.
Table 3. Related Links
PARTS
PRODUCT FOLDER
SAMPLE & BUY
TECHNICAL
DOCUMENTS
TOOLS &
SOFTWARE
SUPPORT &
COMMUNITY
ISO7420
Click here
Click here
Click here
Click here
Click here
ISO7420M
Click here
Click here
Click here
Click here
Click here
ISO7421
Click here
Click here
Click here
Click here
Click here
ISO7421M
Click here
Click here
Click here
Click here
Click here
12.3 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
12.4 Trademarks
DeviceNet, E2E are trademarks of Texas Instruments.
All other trademarks are the property of their respective owners.
12.5 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
12.6 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
13 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
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PACKAGE OPTION ADDENDUM
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10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
ISO7420D
ACTIVE
SOIC
D
8
75
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
IS7420
ISO7420DR
ACTIVE
SOIC
D
8
2500
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
IS7420
ISO7420MD
ACTIVE
SOIC
D
8
75
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
I7420M
ISO7420MDR
ACTIVE
SOIC
D
8
2500
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
I7420M
ISO7421D
ACTIVE
SOIC
D
8
75
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
IS7421
ISO7421DR
ACTIVE
SOIC
D
8
2500
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
IS7421
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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