ISO1540-Q1, ISO1541-Q1
SLLSEX0D – NOVEMBER 2016 – REVISED DECEMBER 2022
ISO154x-Q1 Low-Power Bidirectional I2C Isolators
1 Features
3 Description
•
•
The ISO1540-Q1 and ISO1541-Q1 devices are lowpower, bidirectional isolators that are compatible
with I2C interfaces. These devices have logic input
and output buffers that are separated by Texas
Instruments Capacitive Isolation technology using a
silicon dioxide (SiO2) barrier. When used with isolated
power supplies, these devices block high voltages,
isolate grounds, and prevent noise currents from
entering the local ground and interfering with or
damaging sensitive circuitry.
•
•
•
•
•
•
2 Applications
•
•
•
•
•
•
•
Electric and hybrid-electric vehicles
Isolated I2C buses
SMBus and PMBus interfaces
Open-drain networks
Motor control systems
Battery management
I2C level shifting
This isolation technology provides for function,
performance,
size,
and
power
consumption
advantages when compared to optocouplers. The
ISO1540-Q1 and ISO1541-Q1 devices enable a
complete isolated I2C interface to be implemented
within a small form factor.
The ISO1540-Q1 has two isolated bidirectional
channels for clock and data lines while the ISO1541Q1 has a bidirectional data and a unidirectional clock
channel. The ISO1541-Q1 is useful in applications
that have a single controller while the ISO1540Q1 is suitable for multi-controller applications. For
applications where clock stretching by the target is
possible, the ISO1540-Q1 device should be used.
Isolated bidirectional communication is accomplished
within these devices by offsetting the low-level output
voltage on side 1 to a value greater than the highlevel input voltage on side 1, thus preventing an
internal logic latch that otherwise would occur with
standard digital isolators.
Device Information
PART NUMBER
ISO1540-Q1
ISO1541-Q1
PACKAGE
SOIC (8)
BODY SIZE (NOM)
4.90 mm × 3.91 mm
VCC1
VCC2
Isolation Capacitor
•
Qualified for automotive applications
AEC-Q100 qualified with the following results:
– Device temperature grade 1: –40°C to +125°C
ambient operating temperature
– Device HBM ESD classification level 3A
– Device CDM ESD classification level C6
Functional Safety-Capable
– Documentation available to aid functional safety
system design: ISO1540-Q1, ISO1541-Q1
Isolated bidirectional, I2C compatible,
communication
Supports up to 1-MHz operation
3-V to 5.5-V supply range
Open-drain outputs With 3.5-mA Side 1 and 35mA Side 2 sink current capability
±50-kV/µs transient immunity (Typical)
Safety-related certifications:
– 4242-VPK isolation per DIN EN IEC 60747-17
(VDE 0884-17)
– 2500-VRMS isolation for 1 minute per UL 1577
– CSA approval per IEC 62368-1 end equipment
standard
– CQC basic insulation per GB4943.1-2011
SDA1
or SCL1
GND1
SDA2
or SCL2
GND2
VREF
Simplified Schematic
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
ISO1540-Q1, ISO1541-Q1
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Table of Contents
1 Features............................................................................1
2 Applications..................................................................... 1
3 Description.......................................................................1
4 Revision History.............................................................. 2
5 Pin Configuration and Functions...................................3
6 Specifications.................................................................. 5
6.1 Absolute Maximum Ratings........................................ 5
6.2 ESD Ratings............................................................... 5
6.3 Recommended Operating Conditions.........................5
6.4 Thermal Information....................................................6
6.5 Power Ratings.............................................................6
6.6 Insulation Specifications............................................. 7
6.7 Safety-Related Certifications...................................... 8
6.8 Safety Limiting Values.................................................8
6.9 Electrical Characteristics.............................................9
6.10 Supply Current Characteristics............................... 10
6.11 Timing Requirements.............................................. 10
6.12 Switching Characteristics........................................ 11
6.13 Insulation Characteristics Curves........................... 12
6.14 Typical Characteristics............................................ 13
7 Detailed Description......................................................18
7.1 Overview................................................................... 18
7.2 Functional Block Diagrams....................................... 18
7.3 Feature Description...................................................19
7.4 Isolator Functional Principle......................................19
7.5 Device Functional Modes..........................................20
8 Application and Implementation.................................. 21
8.1 Application Information............................................. 21
8.2 Typical Application.................................................... 22
9 Power Supply Recommendations................................25
10 Layout...........................................................................26
10.1 Layout Guidelines................................................... 26
10.2 Layout Example...................................................... 26
11 Device and Documentation Support..........................27
11.1 Documentation Support.......................................... 27
11.2 Related Links.......................................................... 27
11.3 Receiving Notification of Documentation Updates.. 27
11.4 Community Resources............................................27
11.5 Trademarks............................................................. 27
12 Mechanical, Packaging, and Orderable
Information.................................................................... 27
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision C (November 2021) to Revision D (December 2022)
Page
2
• Changed all instances of legacy terminology to controller and target where I C is mentioned.......................... 1
• Editorial and cosmetic changes throughout the document................................................................................. 1
• Updated electrical and switching parameters..................................................................................................... 5
• Updated 'DIN VDE V 0884-11:2017-01' to 'DIN EN IEC 60747-17 (VDE 0884-17)' and removed references to
'CSA/IEC 60950-1'..............................................................................................................................................8
Changes from Revision B (October 2020) to Revision C (November 2021)
Page
• Changed scaling on mutiple images.................................................................................................................23
Changes from Revision A ( March 2019) to Revision B (October 2020)
Page
• Added Section 1 bullet for Functional Safety Information...................................................................................1
Changes from Revision * ( November 2016) to Revision A (March 2019)
Page
• Changed VDE Standard name From: DIN V VDE V 0884-10 (VDE V 0884-10): 2006-12 To: DIN VDE V
0884-11:2017-01 in Section 1 ............................................................................................................................1
• Changed Section 1 bullet From: CSA Component Acceptance Notice 5A, IEC 60950-1 and IEC 61010-1 End
Equipment Standards To: CSA approval per IEC 60950-1 and IEC 62368-1 end equipment standards........... 1
• Deleted Section 1 bullet: UL 1577 Certification Complete; All Other Certifications Planned..............................1
• Updated certifications approval status, numbers, standard names, and details according to the latest agency
certificates in Section 6.7 table........................................................................................................................... 8
• Changed both bypass capacitors From: 10 µF To: 0.1 µF in . Even though larger capacitors can be used, 0.1
µF is the minimum recommended bypass capacitor size................................................................................. 23
• Changed both bypass capacitors From: 10 µF To: 0.1 µF in . Even though larger capacitors can be used, 0.1
µF is the minimum recommended bypass capacitor size................................................................................. 23
2
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5 Pin Configuration and Functions
1
8
VCC2
SDA1
2
7
SDA2
SCL1
3
6
SCL2
GND1
4
5
GND2
Isolation
VCC1
Side 1
Side 2
Not to scale
Figure 5-1. ISO1540-Q1 D Package 8-Pin SOIC Top View
Table 5-1. Pin Functions—ISO1540-Q1
PIN
I/O
DESCRIPTION
NAME
NO.
GND1
4
—
Ground, side 1
GND2
5
—
Ground, side 2
SCL1
3
I/O
Serial clock input / output, side 1
SCL2
6
I/O
Serial clock input / output, side 2
SDA1
2
I/O
Serial data input / output, side 1
SDA2
7
I/O
Serial data input / output, side 2
VCC1
1
—
Supply voltage, side 1
VCC2
8
—
Supply voltage, side 2
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1
8
VCC2
SDA1
2
7
SDA2
SCL1
3
6
SCL2
GND1
4
5
GND2
Isolation
VCC1
Side 1
Side 2
Not to scale
Figure 5-2. ISO1541-Q1 D Package 8-Pin SOIC Top View
Table 5-2. Pin Functions—ISO1541-Q1
PIN
4
I/O
DESCRIPTION
NAME
NO.
GND1
4
—
Ground, side 1
GND2
5
—
Ground, side 2
SCL1
3
I
Serial clock input, side 1
SCL2
6
O
Serial clock output, side 2
SDA1
2
I/O
Serial data input / output, side 1
SDA2
7
I/O
Serial data input / output, side 2
VCC1
1
—
Supply voltage, side 1
VCC2
8
—
Supply voltage, side 2
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6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted)(1) (2)
Voltage
MIN
MAX
VCC1, VCC2
–0.5
6
SDA1, SCL1
–0.5
VCC1 + 0.5(3)
SDA2, SCL2
–0.5
VCC2 + 0.5(3)
SDA1, SCL1
0
20
SDA2, SCL2
0
100
IO
Output current
TJ(MAX)
Maximum junction temperature
Tstg
Storage temperature
(1)
(2)
(3)
–65
UNIT
V
mA
150
°C
150
°C
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress
ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under
Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device
reliability.
All voltage values here within are with respect to the local ground pin (GND1 or GND2) and are peak voltage values.
Maximum voltage must not exceed 6 V.
6.2 ESD Ratings
VALUE
V(ESD)
Electrostatic discharge
Human-body model (HBM), per AEC
Q100-002(1)
All pins except bus pins
±4000
Bus pins
±8000
Charged-device model (CDM), per AEC Q100-011
(1)
UNIT
V
±1500
AEC Q100-002 indicates that HBM stressing shall be in accordance with the ANSI/ESDA/JEDEC JS-001 specification.
6.3 Recommended Operating Conditions
MIN
MAX
UNIT
VCC1, VCC2
Supply voltage
3
5.5
V
VSDA1, VSCL1
Input and output signal voltages, side 1
0
VCC1
V
VSDA2, VSCL2
Input and output signal voltages, side 2
0
VCC2
V
VIL1
Low-level input voltage, side 1
0
0.5
V
VIH1
High-level input voltage, side 1
0.7 × VCC1
VCC1
V
VIL2
Low-level input voltage, side 2
0
0.3 × VCC2
V
VIH2
High-level input voltage, side 2
0.7 × VCC2
VCC2
IOL1
Output current, side 1
0.5
3.5
mA
IOL2
Output current, side 2
0.5
35
mA
C1
Capacitive load, side 1
40
pF
C2
Capacitive load, side 2
400
fMAX
Operating frequency(1)
1
TA
Ambient temperature
–40
125
°C
TJ
Junction temperature
–40
136
°C
TSD
Thermal shutdown
139
197
°C
(1)
V
pF
MHz
This represents the maximum frequency with the maximum bus load (C) and the maximum current sink (IO). If the system has less bus
capacitance, then higher frequencies can be achieved.
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6.4 Thermal Information
ISO154x-Q1
THERMAL
METRIC(1)
UNIT
D (SOIC)
8 PINS
RθJA
Junction-to-ambient thermal resistance
114.6
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
69.6
°C/W
RθJB
Junction-to-board thermal resistance
55.3
°C/W
ψJT
Junction-to-top characterization parameter
27.2
°C/W
ψJB
Junction-to-board characterization parameter
54.7
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
N/A
°C/W
(1)
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report (SPRA953).
6.5 Power Ratings
PARAMETER
6
TEST CONDITIONS
PD
Maximum power dissipation (both sides)
PD1
Maximum power dissipation (side-1)
PD2
Maximum power dissipation (side-2)
VCC1 = VCC2 = 5.5 V, TJ = 150 °C, C1
= 20 pF, C2 = 400 pF; R1 = 1.4 kΩ, R2 =
94 Ω; Input a 1-MHz 50% duty cycle clock
signal
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MIN
TYP
MAX
UNIT
105
mW
37
mW
68
mW
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6.6 Insulation Specifications
PARAMETER
TEST CONDITIONS
VALUE
UNIT
GENERAL
CLR
External clearance(1)
Shortest terminal-to-terminal distance through air
>4
mm
CPG
External creepage(1)
Shortest terminal-to-terminal distance across the
package surface
>4
mm
DTI
Distance through the insulation
Minimum internal gap (internal clearance)
0.014
mm
CTI
Comparative tracking index
DIN EN 60112 (VDE 0303-11); IEC 60112
>400
V
Rated mains voltage ≤ 150 VRMS
I–IV
Rated mains voltage ≤ 300 VRMS
I–III
Material group
II
Overvoltage category
DIN EN IEC 60747-17 (VDE 0884-17)(2)
VIORM
VIOTM
Maximum repetitive peak isolation voltage AC voltage (bipolar)
Maximum transient isolation voltage
Apparent charge(3)
qpd
Barrier capacitance, input to output(4)
CIO
Isolation resistance, input to output(4)
RIO
VTEST = VIOTM
t = 60 s (qualification)
t = 1 s (100% production)
566
VPK
4242
VPK
Method a: After I/O safety test subgroup 2/3, Vini =
VIOTM, tini = 60 s; Vpd(m) = 1.2 × VIORM = 680 VPK, tm
= 10 s
109
Pollution degree
2
Climatic category
40/125/21
pC
pF
Ω
UL 1577
VISO
(1)
(2)
(3)
(4)
Withstand isolation voltage
VTEST = VISO = 2500 VRMS, t = 60 s (qualification);
VTEST = 1.2 × VISO = 3000 VRMS, t = 1 s (100%
production)
2500
VRMS
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.
This coupler is suitable for basic electrical insulation only within the maximum operating ratings. Compliance with the safety ratings
shall be ensured by means of suitable protective circuits.
Apparent charge is electrical discharge caused by a partial discharge (pd).
All pins on each side of the barrier tied together creating a two-terminal device
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6.7 Safety-Related Certifications
VDE
CSA
UL
CQC
Certified according to DIN EN IEC
60747-17 (VDE 0884-17) and DIN
EN 61010-1 (VDE 0411-1)
Certified according to CSA/IEC
62368-1
Recognized under UL
1577 Component Recognition
Program
Certified according to
GB4943.1-2011
Basic Insulation
Maximum Transient Overvoltage,
4242 VPK;
Maximum Repetitive Peak Voltage,
566 VPK
2.5-kVRMS Insulation Rating;
300 VRMS Basic Insulation
working voltage per CSA
62368-1-14 and IEC
62368-1:2014
Single protection, 2500 VRMS
Basic Insulation, Altitude ≤ 5000
m, Tropical Climate, 250 VRMS
maximum working voltage
Certificate number: 40047657
Master contract number: 220991 File number: E181974
Certificate number:
CQC14001109540
6.8 Safety Limiting Values
Safety limiting intends to minimize 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
IS
TS
Safety input, output, or supply
current
TEST CONDITIONS
MIN
TYP
MAX
RθJA = 114.6°C/W, VI = 5.5 V, TJ = 150°C, TA = 25°C,
see Figure 6-1
198
RθJA = 114.6°C/W, VI = 3.6 V, TJ = 150°C, TA = 25°C,
see Figure 6-1
303
Safety temperature
UNIT
mA
150
°C
The safety-limiting constraint is the maximum junction temperature specified in the data sheet. 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 Section 6.4 table is that of a
device installed on a high-K test board for leaded surface-mount packages. 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.
8
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6.9 Electrical Characteristics
over recommended operating conditions, unless otherwise noted
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
SIDE 1 (ONLY)
VILT1
Voltage input threshold low, SDA1
and SCL1
480
550
660
mV
VIHT1
Voltage input threshold high, SDA1
and SCL1
520
610
700
mV
VHYST1
Voltage input hysteresis
40
60
VOL1
Low-level output voltage, SDA1 and
0.5 mA ≤ (ISDA1 and ISCL1) ≤ 3.5 mA
SCL1(1)
ΔVOIT1
Low-level output voltage to highlevel input voltage threshold
difference, SDA1 and SCL1(1) (2)
VIHT1 –VILT1
570
0.5 mA ≤ (ISDA1 and ISCL1) ≤ 3.5 mA
mV
800
50
mV
mV
SIDE 2 (ONLY)
VILT2
Voltage input threshold low, SDA2
and SCL2
0.3 × VCC2
0.4 × VCC2
V
VIHT2
Voltage input threshold high, SDA2
and SCL2
0.4 × VCC2
0.5 × VCC2
V
VHYST2
Voltage input hysteresis
VOL2
Low-level output voltage, SDA2 and
0.5 mA ≤ (ISDA2 and ISCL2) ≤ 35 mA
SCL2
VIHT2 – VILT2
0.05 × VCC2
V
0.4
V
10
µA
BOTH SIDES
|II|
Input leakage currents, SDA1,
SCL1, SDA2, and SCL2
VSDA1, VSCL1 = VCC1;
VSDA2, VSCL2 = VCC2
CI
Input capacitance to local ground,
SDA1, SCL1, SDA2, and SCL2
VI = 0.4 × sin(2E6πt) + 2.5 V
CMTI
Common-mode transient immunity
See Figure 7-3
VCCUV
VCC undervoltage lockout
threshold(3)
(1)
(2)
(3)
0.01
7
pF
25
50
kV/µs
1.7
2.5
2.9
V
This parameter does not apply to the ISO1541-Q1 SCL1 line as it is unidirectional.
∆VOIT1 = VOL1 – VIHT1. This represents the minimum difference between a Low-Level Output Voltage and a High-Level Input Voltage
Threshold to prevent a permanent latch condition that would otherwise exist with bidirectional communication.
Any VCC voltages, on either side, less than the minimum will ensure device lockout. Both VCC voltages greater than the maximum will
prevent device lockout.
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6.10 Supply Current Characteristics
over recommended operating conditions, unless otherwise noted. For more information, see Figure 7-1.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
VSDA1, VSCL1 = GND1; VSDA2, VSCL2 = GND2;
R1, R2 = Open; C1, C2 = Open
2.4
7.1
VSDA1, VSCL1 = VCC1; VSDA2, VSCL2 = VCC2;
R1, R2 = Open; C1, C2 = Open
2.5
4
VSDA1, VSCL1 = GND1; VSDA2, VSCL2 = GND2;
R1, R2 = Open; C1, C2 = Open
2.1
6.1
VSDA1, VSCL1 = VCC1; VSDA2, VSCL2 = VCC2;
R1, R2 = Open; C1, C2 = Open
2.3
3.6
VSDA1, VSCL1 = GND1; VSDA2, VSCL2 = GND2;
R1, R2 = Open; C1, C2 = Open
1.7
6.7
VSDA1, VSCL1 = VCC1; VSDA2, VSCL2 = VCC2;
R1, R2 = Open; C1, C2 = Open
1.9
3.5
VSDA1, VSCL1 = GND1; VSDA2, VSCL2 = GND2;
R1,R2 = Open; C1,C2 = Open
3.1
7.2
VSDA1, VSCL1 = VCC1; VSDA2, VSCL2 = VCC2;
R1, R2 = Open; C1, C2 = Open
3.1
4.7
VSDA1, VSCL1 = GND1; VSDA2, VSCL2 = GND2;
R1, R2 = Open; C1, C2 = Open
2.8
6.2
VSDA1, VSCL1 = VCC1; VSDA2, VSCL2 = VCC2;
R1, R2 = Open; C1, C2 = Open
2.9
4.5
VSDA1, VSCL1 = GND1; VSDA2, VSCL2 = GND2;
R1, R2 = Open; C1, C2 = Open
2.3
6.8
VSDA1, VSCL1 = VCC1; VSDA2, VSCL2 = VCC2;
R1, R2 = Open; C1, C2 = Open
2.5
4
UNIT
3 V ≤ VCC1, VCC2 ≤ 3.6 V
ISO1540-Q1
ICC1
Supply current, side 1
ISO1541-Q1
ICC2
Supply current, side 2
ISO1540-Q1 and
ISO1541-Q1
mA
mA
4.5 V ≤ VCC1, VCC2 ≤ 5.5 V
ISO1540-Q1
ICC1
Supply current, side 1
ISO1541-Q1
ICC2
Supply current, side 2
ISO1540-Q1 and
ISO1541-Q1
mA
mA
6.11 Timing Requirements
tUVLO
10
Time to recover from UVLO
2.7 V to 0.9 V; See Figure 7-4
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MIN
NOM
MAX
UNIT
30
50
151
µs
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6.12 Switching Characteristics
over recommended operating conditions, unless otherwise noted
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
8
17
29
UNIT
3 V ≤ VCC1, VCC2 ≤ 3.6 V
Output Signal Fall Time
(SDA1, SCL1)
See Figure 7-1
R1 = 953 Ω,
C1 = 40 pF
0.7 × VCC1 to 0.3 × VCC1
tf1
0.9 × VCC1 to 900 mV
16
29
48
Output Signal Fall Time
(SDA2, SCL2)
See Figure 7-1
R2 = 95.3 Ω,
C2 = 400 pF
0.7 × VCC2 to 0.3 × VCC2
14
23
47
tf2
0.9 × VCC2 to 400 mV
35
50
100
tpLH1-2
Low-to-High Propagation
Delay, Side 1 to Side 2
0.55 V to 0.7 × VCC2
33
65
ns
tPHL1-2
High-to-Low Propagation
Delay, Side 1 to Side 2
0.7 V to 0.4 V
90
181
ns
PWD1-2
Pulse Width Distortion
|tpHL1-2 – tpLH1-2|
55
123
ns
tPLH2-1 (1)
Low-to-High Propagation
Delay, Side 2 to Side 1
0.4 × VCC2 to 0.7 × VCC1
47
68
ns
tPHL2-1 (1)
High-to-Low Propagation
Delay, Side 2 to Side 1
0.4 × VCC2 to 0.9 V
67
109
ns
PWD2-1 (1)
Pulse Width Distortion
|tpHL2-1 – tpLH2-1|
20
49
ns
tLOOP1 (1)
Round-trip propagation
delay on Side 1
100
165
ns
6
11
22
See Figure 7-1
R1 = 953 Ω,
R2 = 95.3 Ω,
C1, C2 = 10 pF
See Figure 7-2;
R1 = 953 Ω, C1 = 40 pF
R2 = 95.3 Ω, C2 = 400 pF
0.4 V to 0.3 × VCC1
ns
ns
4.5 V ≤ VCC1, VCC2 ≤ 5.5 V
Output Signal Fall Time
(SDA1, SCL1)
See Figure 7-1
R1 = 1430 Ω,
C1 = 40 pF
0.7 × VCC1 to 0.3 × VCC1
tf1
0.9 × VCC1 to 900 mV
13
21
48
Output Signal Fall Time
(SDA2, SCL2)
See Figure 7-1
R2 = 143 Ω,
C2 = 400 pF
0.7 × VCC2 to 0.3 × VCC2
10
18
35
tf2
0.9 × VCC2 to 400 mV
28
41
76
tpLH1-2
Low-to-High Propagation
Delay, Side 1 to Side 2
0.55 V to 0.7 × VCC2
31
62
ns
tPHL1-2
High-to-Low Propagation
Delay, Side 1 to Side 2
0.7 V to 0.4 V
70
139
ns
PWD1-2
Pulse Width Distortion
|tpHL1-2 – tpLH1-2|
38
80
ns
tPLH2-1 (1)
Low-to-high propagation
delay, side 2 to side 1
0.4 × VCC2 to 0.7 × VCC1
55
80
ns
tPHL2-1 (1)
High-to-low propagation
delay, Side 2 to side 1
0.4 × VCC2 to 0.9 V
47
85
ns
PWD2-1 (1)
Pulse Width Distortion
|tpHL2-1 – tpLH2-1|
8
34
ns
tLOOP1 (1)
Round-trip propagation
delay on side 1
110
180
ns
(1)
See Figure 7-1
R1 = 1430 Ω,
R2 = 143 Ω,
C1,2 = 10 pF
See Figure 7-2;
R1 = 1430 Ω, C1 = 40 pF
R2 = 143 Ω, C2 = 400 pF
0.4 V to 0.3 × VCC1
ns
ns
This parameter does not apply to the ISO1541-Q1 SCL1 line as it is unidirectional.
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6.13 Insulation Characteristics Curves
350
VCC1 = VCC2 = 3.6 V
VCC1 = VCC2 = 5.5 V
Safety Limiting Current (mA)
300
250
200
150
100
50
0
0
50
100
150
Ambient Temperature (qC)
200
Figure 6-1. Thermal Derating Curve for Limiting Current per VDE
12
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6.14 Typical Characteristics
0.800
3.0
IOL1 = 3.5 mA
IOL1 = 0.5 mA
2.5
0.760
Output Current, IOL1 (mA)
Output Voltage, VOL1 (V)
0.780
0.740
0.720
0.700
0.680
0.660
0.640
2.0
1.5
1.0
0.5
0.0
-0.5
0.620
−40 −25 −10
5
20 35 50 65 80
Free−Air Temperature (°C)
95
16
16
14
14
Fall Time, tf1 (ns)
Fall Time, tf1 (ns)
18
8
6
4
0.6
0.7
0.8
0.9
R1 = 1430 :
R1 = 2.2 k:
12
10
8
6
4
R1= 953 :
R1= 2.2 k:
2
-25
-10
5
20 35 50 65 80
Free-Air Temperature (qC)
95
2
0
-40
110 125
Figure 6-4. Side 1: Output Fall Time vs Free-Air
Temperature
25
Fall Time tf2 (ns)
25
20
15
10
5
20 35 50 65 80
Free-Air Temperature (qC)
95
20 35 50 65 80
Free-Air Temperature (qC)
110 125
Figure 6-6. Side 2: Output Fall Time vs Free-Air
Temperature
110 125
D002
15
10
0
-40
R2 = 143 :
R2 = 2.2 k:
-25
-10
D003
VCC2 = 3.3 V
C2 = 400 pF
Fall time measured from 70% to 30% VCC2
95
20
5
R2 = 95.3 :
R2 = 2.2 k:
-10
5
Figure 6-5. Side 1: Output Fall Time vs Free-air
Temperature
30
-25
-10
VCC1 = 5 V
C1 = 40 pF
Fall time measured from 70% to 30% VCC1
30
5
-25
D001
VCC1 = 3.3 V
C1 = 40 pF
Fall time measured from 70% to 30% VCC1
Fall Time tf2 (ns)
0.5
Figure 6-3. Side 1: Output Low Current vs SDA1 or
SCL1 Applied Voltage
20
10
0.4
TA = 25°C
18
12
0.3
Applied Voltage, VSDA1, VSCL1 (V)
20
0
-40
0.2
110 125
Figure 6-2. Side 1: Output Low Voltage vs Free-Air
Temperature
0
-40
0.1
0
0.600
5
20 35 50 65 80
Free-Air Temperature (qC)
95
110 125
D004
VCC2 = 5 V
C2 = 400 pF
Fall time measured from 70% to 30% VCC2
Figure 6-7. Side 2: Output Fall Time vs Free-Air
Temperature
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45
120
Propagation Delay, tPHL1-2 (ns)
Propagation Delay, t PLH1-2 (ns)
40
35
30
25
20
15
10
VCC1 and VCC2 = 3.3 V, R2 = 95.3 :
VCC1 and VCC2 = 5 V, R2 = 143 :
5
0
-40
-25
-10
5
20 35 50 65 80
Free-Air Temperature (qC)
95
100
80
60
40
20
0
-40
110 125
1045
95
110 125
D006
80
Propagation Delay, t PHL1-2 (ns)
Propagation Delay, tPLH1-2 (ns)
20 35 50 65 80
Free-Air Temperature (qC)
90
VCC1 and VCC2 = 3.3 V
VCC1 and VCC2 = 5 V
1040
1035
1030
1025
1020
1015
1010
1005
70
60
50
40
30
20
VCC1 and VCC2 = 3.3 V
VCC1 and VCC2 = 5 V
10
-25
-10
5
20 35 50 65 80
Free-Air Temperature (qC)
R2 = 2.2 kΩ
95
0
-40
110 125
C2 = 400 pF
70
Propagation Delay, t PHL2-1 (ns)
60
50
40
30
20
5
20 35 50 65 80
Free-Air Temperature (qC)
20 35 50 65 80
Free-Air Temperature (qC)
95
110 125
110 125
D008
C2 = 400 pF
50
40
30
20
0
-40
VCC1 and VCC2 = 3.3 V, R1 = 953 :
VCC1 and VCC2 = 5 V, R1 = 1430 :
-25
-10
D009
C1 = 10 pF
95
60
10
VCC1 and VCC2 = 3.3 V, R1 = 953 :
VCC1 and VCC2 = 5 V, R1 = 1430 :
-10
5
Figure 6-11. tPHL1-2 Propagation Delay vs Free-Air
Temperature
80
-25
-10
R2 = 2.2 kΩ
70
10
-25
D007
Figure 6-10. tPLH1-2 Propagation Delay vs Free-Air
Temperature
Propagation Delay, t PHL2-1 (ns)
5
Figure 6-9. tPHL1-2 Propagation Delay vs Free-Air
Temperature
1050
5
20 35 50 65 80
Free-Air Temperature (qC)
95
110 125
D010
C1 = 10 pF
Figure 6-12. tPLH2-1 Propagation Delay vs Free-Air
Temperature
14
-10
C2 = 10 pF
Figure 6-8. tPLH1-2 Propagation Delay vs Free-Air
Temperature
0
-40
-25
D005
C2 = 10 pF
1000
-40
VCC1 and VCC2 = 3.3 V, R2 = 95.3 :
VCC1 and VCC2 = 5 V, R2 = 143 :
Figure 6-13. tPHL2-1 Propagation Delay vs Free-Air
Temperature
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148
80
146
70
Propagation Delay, t PHL2-1 (ns)
Propagation Delay, tPLH2-1 (ns)
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144
142
140
138
136
134
132
-40
VCC1 and VCC2 = 3.3 V
VCC1 and VCC2 = 5 V
-25
-10
5
20 35 50 65 80
Free-Air Temperature (qC)
R1 = 2.2 kΩ
95
60
50
40
30
20
VCC1 and VCC2 = 3.3 V
VCC1 and VCC2 = 5 V
10
0
−40 −25 −10
110 125
5
20 35 50 65 80
Free-Air Temperature (°C)
D011
C1 = 40 pF
R1 = 2.2 kΩ
Figure 6-14. tPLH2-1 Propagation Delay vs Free-Air
Temperature
95
110 125
C1 = 40 pF
Figure 6-15. tPHL2-1 Propagation Delay vs Free-Air
Temperature
140
600
120
595
tLOOP1 (ns)
tLOOP1 (ns)
100
80
60
590
585
40
580
20
0
-40
VCC1 and VCC2 = 3.3 V
VCC1 and VCC2 = 5 V
VCC1 and VCC2 = 3.3 V, R1 = 953 :, R2 = 95.3 :
VCC1 and VCC2 = 5 V, R1 = 1430 :, R2 = 143 :
-25
-10
5
20 35 50 65 80
Free-Air Temperature (qC)
C1 = 40 pF
95
110 125
-25
-10
5
D013
C2 = 400 pF
Figure 6-16. tLOOP1 vs Free-Air Temperature
Common-Mode Transient Immunity (kV/Ps)
575
-40
20 35 50 65 80
Free-Air Temperature (qC)
C1 = 40 pF
R1 = 2.2 kΩ
95
110 125
D014
C2 = 400 pF
R2 = 2.2 kΩ
Figure 6-17. tLOOP1 vs Free-Air Temperature
70
60
50
40
30
20
10
VCC1 and VCC2 = 3.3 V
VCC1 and VCC2 = 5 V
0
-40
-25
-10
5
20 35 50 65 80
Free-Air Temperature (qC)
95
110 125
D015
Figure 6-18. CMTI vs Free-Air Temperature
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Parameter Measurement Information
VCC1
R1
±
+
±
+
R1
VCC2
R2
SDA1
R2
SDA2
ISO1540
ISO1541
SCL2
SCL1
C1
C1
C2
C2
Copyright © 2016, Texas Instruments Incorporated
Figure 7-1. Test Diagram
VCC2
VCC1
SDA1 or
SCL1
Output
R1
Isolation
VCC1
GND1
C1
tLOOP1
0.3 VCC1
SDA1
SCL1 (ISO1540 Only)
0.4 V
GND1
Copyright © 2016, Texas Instruments Incorporated
Figure 7-2. tLoop1 Setup and Timing Diagram
VCCx
VCCy
2k
2k
Input
Isolation
+
Output
±
GNDx
GNDy
VCMTI
Figure 7-3. Common-Mode Transient Immunity Test Circuit
16
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VCCx
VCCy
VCCx
Ry
SDAx or
SCLx
I solatio n
0V
Side x, Side y VCCx,VCCy
Ry
1, 2
3.3 V, 3.3 V 95.3 Ω
2, 1
3.3 V, 3.3 V 953 Ω
+
Output
GNDy
GNDx
or
VCCx
VCCy
VCCy
Ry
SDAx or
SCLx
Isola tion
0V
+
Output
GNDx
GNDy
VCCx or
VCCy
VCCx (UVLO+)
t
UVLO
0 .9 V
Output
Figure 7-4. tUVLO Test Circuit and Timing Diagrams
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7 Detailed Description
7.1 Overview
The I2C bus is used in a wide range of applications because it is simple to use. The bus consists of a two-wire
communication bus that supports bidirectional data transfer between a controller device and several target
devices. The controller, or processor, controls the bus, specifically the serial clock (SCL) line. Data is transferred
between the controller and target through a serial data (SDA) line. This data can be transferred in four speeds:
standard mode (0 to 100 kbps), fast mode (0 to 400 kbps), fast-mode plus (0 to 1 Mbps), and high-speed mode
(0 to 3.4 Mbps). The most common speeds are the standard and fast modes.
The I2C bus operates in bidirectional, half-duplex mode, while standard digital isolators are unidirectional
devices. To make efficient use of one technology supporting the other, external circuitry is required that
separates the bidirectional bus into two unidirectional signal paths without introducing significant propagation
delay. These devices have their logic input and output buffers separated by TI's capacitive isolation technology
using a silicon dioxide (SiO2) barrier. When used in conjunction with isolated power supplies, these devices
block high voltages, isolate grounds, and prevent noise currents from entering the local ground and interfering
with or damaging sensitive circuitry.
7.2 Functional Block Diagrams
VCC1
VCC2
SDA2
VREF
Isolation Capacitor
SDA1
SCL1
SCL2
GND1
GND2
VREF
Figure 7-1. ISO1540-Q1 Block Diagram
18
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VCC2
SDA1
SDA2
Isolation Capacitor
VCC1
VREF
SCL1
SCL2
GND1
GND2
Figure 7-2. ISO1541-Q1 Block Diagram
7.3 Feature Description
The device enables a complete isolated I2C interface to be implemented within a small form factor having the
features listed in Table 7-1.
Table 7-1. Features List
(1)
PART NUMBER
CHANNEL DIRECTION
ISO1540-Q1
Bidirectional (SCL)
Bidirectional (SDA)
ISO1541-Q1
Unidirectional (SCL)
Bidirectional (SDA)
RATED ISOLATION(1)
MAXIMUM FREQUENCY
2500 VRMS
4242 VPK
1 MHz
See Section 6.7 for detailed Isolation specifications.
7.4 Isolator Functional Principle
To isolate a bidirectional signal path (SDA or SCL), the ISO1540-Q1 internally splits a bidirectional line into two
unidirectional signal lines, each of which is isolated through a single-channel digital isolator. Each channel output
is made open-drain to comply with the open-drain technology of I2C. Side 1 of the ISO1540-Q1 connects to a
low-capacitance I2C node, while side 2 is designed for connecting to a fully loaded I2C bus with up to 400 pF of
capacitance.
VCC1
VCC2
A
RPU1
SDA1
VC-out
RPU2
B
SDA2
ISO1540
40 mV
Cnode
50 mV
Cbus
C
VSDA1
D
VILT1
VIHT1
VOL1
GND1
VREF
GND2
Figure 7-3. SDA Channel Design and Voltage Levels at SDA1
At first sight, the arrangement of the internal buffers suggests a closed signal loop that is prone to latch-up.
However, this loop is broken by implementing an output buffer (B) whose output low-level is raised by a diode
drop to approximately 0.75 V, and the input buffer (C) that consists of a comparator with defined hysteresis.
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The comparator’s upper and lower input thresholds then distinguish between the proper low-potential of 0.4 V
(maximum) driven directly by SDA1 and the buffered output low-level of B.
Figure 7-4 demonstrate the switching behavior of the I2C isolator, ISO1540-Q1, between a controller node at
SDA1 and a heavy loaded bus at SDA2.
VCC2
VOL1
SDA1
50%
SDA2
VIHT1
30%
Receive
Delay
Receive
Delay
VCC1
Receive
Delay
Transmit
Delay
VCC1
VCC2
VCC2
SDA2
50%
SDA1
VCC1
VCC1
VCC2
Transmit
Delay
VIHT2
30%
Figure 7-4. SDA Channel Timing in Receive and Transmit Directions
7.4.1 Receive Direction (Left Diagram of )
When the I2C bus drives SDA2 low, SDA1 follows after a certain delay in the receive path. The output low is the
buffered output of VOL1 = 0.75 V, which is sufficiently low to be detected by Schmitt-trigger inputs with a minimum
input-low voltage of VIL = 0.9 V at 3 V supply levels.
When SDA2 is released, its voltage potential increases towards VCC2 following the time-constant formed
by RPU2 and Cbus. After the receive delay, SDA1 is released and also rises towards VCC1, following the
time-constant RPU1 × Cnode. Because of the significant lower time-constant, SDA1 may reach VCC1 before
SDA2 reaches VCC2 potential.
7.4.2 Transmit Direction (Right Diagram of )
When a controller drives SDA1 low, SDA2 follows after a certain delay in the transmit direction. When SDA2
turns low it also causes the output of buffer B to turn low but at a higher 0.75 V level. This level cannot be
observed immediately as it is overwritten by the lower low-level of the controller.
However, when the controller releases SDA1, the voltage potential increases and first must pass the upper input
threshold of the comparator, VIHT1, to release SDA2. SDA1 then increases further until it reaches the buffered
output level of VOL1 = 0.75 V, maintained by the receive path. When comparator C turns high, SDA2 is released
after the delay in transmit direction. It takes another receive delay until B’s output turns high and fully releases
SDA1 to move toward VCC1 potential.
7.5 Device Functional Modes
Table 7-2 lists the ISO154x-Q1 functional modes.
Table 7-2. Function Table
(1)
20
POWER STATE
INPUT
OUTPUT
VCC1 or VCC2 < 2.1 V
X
Z
VCC1 and VCC2 > 2.8 V
L
L
VCC1 and VCC2 > 2.8 V
H
Z
VCC1 and VCC2 > 2.8 V
Z(1)
?
Invalid input condition as an I2C system requires that a pullup resistor to VCC is connected.
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8 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.
8.1 Application Information
8.1.1 I2C Bus Overview
The inter-integrated circuit (I2C) bus is a single-ended, multi-controller, 2-wire bus for efficient inter-IC
communication in half-duplex mode.
I2C uses open-drain technology, requiring two lines, serial data (SDA) and serial clock (SCL), to be connected
to VDD by resistors (see Figure 8-1). Pulling the line to ground is considered a logic zero while letting the line
float is a logic one. This logic is used as a channel access method. Transitions of logic states must occur while
the SCL pin is low. Transitions while the SCL pin is high indicate START and STOP conditions. Typical supply
voltages are 3.3 V and 5 V, although systems with higher or lower voltages are allowed.
VDD
RPU
RPU
RPU
RPU
RPU
RPU
RPU
RPU
SDA
SCL
SDA
SCL
GND
C
Controller
SDA
SCL
SDA
GND
ADC
Target
SCL
GND
DAC
Target
SDA
SCL
GND
C
Target
Figure 8-1. I2C Bus
I2C communication uses a 7-bit address space with 16 reserved addresses, so a theoretical maximum of 112
nodes can communicate on the same bus. In praxis, however, the number of nodes is limited by the specified,
total bus capacitance of 400 pF, which restricts communication distances to a few meters.
The specified signaling rates for the ISO1540-Q1 and ISO1541-Q1 devices are 100 kbps (standard mode), 400
kbps (fast mode), 1 Mbps (fast mode plus).
The bus has two roles for nodes: controller and target. A controller node issues the clock and target addresses,
and also initiates and ends data transactions. A target node receives the clock and addresses and responds to
requests from the controller. Figure 8-2 shows a typical data transfer between controller and target.
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7-bit
ADDRESS
SDA
SCL
1 -7
R/W
ACK
8
9
8-bit
DATA
8-bit
DATA
ACK
1 -8
9
ACK /
NACK
1 -8
9
S
P
START
Condition
STOP
condition
Figure 8-2. Timing Diagram of a Complete Data Transfer
The controller initiates a transaction by creating a START condition, following by the 7-bit address of the target
it wishes to communicate with. This is followed by a single read and write (R/W) bit, representing whether the
controller wishes to write to 0, or to read from 1 the target. The controller then releases the SDA line to allow the
target to acknowledge the receipt of data.
The target responds with an acknowledge bit (ACK) by pulling the SDA pin low during the entire high time of
the 9th clock pulse on the SCL signal, after which the controller continues in either transmit or receive mode
(according to the R/W bit sent), while the target continues in the complementary mode (receive or transmit,
respectively).
The address and the 8-bit data bytes are sent most significant bit (MSB) first. The START bit is indicated by
a high-to-low transition of SDA while SCL is high. The STOP condition is created by a low-to-high transition of
SDA while SCL is high.
If the controller writes to a target, it repeatedly sends a byte with the target sending an ACK bit. In this case, the
controller is in controller-transmit mode and the target is in target-receive mode.
If the controller reads from a target, it repeatedly receives a byte from the target, while acknowledging (ACK) the
receipt of every byte but the last one (see Figure 8-3). In this situation, the controller is in controller-receive mode
and the target is in target-transmit mode.
The controller ends the transmission with a STOP bit, or may send another START bit to maintain bus control for
further transfers.
S Target Address W A
From Controller to Target
DATA
A
DATA
A P
A = acknowledge
A = not acknowledge
Controller Transmitter writing to Target Receiver
S = Start
From Target to Controller
P = Stop
S Target Address R A
DATA
A
DATA
A P
Controller Receiver reading from Target Transmitter
R = Read
W = Write
Figure 8-3. Transmit or Receive Mode Changes During a Data Transfer
When writing to a target, a controller mainly operates in transmit-mode and only changes to receive-mode when
receiving acknowledgment from the target.
When reading from a target, the controller starts in transmit-mode and then changes to receive-mode after
sending a READ request (R/W bit = 1) to the target. The target continues in the complementary mode until the
end of a transaction.
Note
The controller ends a reading sequence by not acknowledging (NACK) the last byte received. This
procedure resets the target state machine and allows the controller to send the STOP command.
8.2 Typical Application
Figure 8-4 shows isolated I2C data acquisition system built with TI microcontroller, analog-to-digital converter,
and I2C isolator, ISO1541-Q1.
22
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Product Folder Links: ISO1540-Q1 ISO1541-Q1
ISO1540-Q1, ISO1541-Q1
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SLLSEX0D – NOVEMBER 2016 – REVISED DECEMBER 2022
The entire circuit operates from a single 3.3-V supply. A low-power push-pull converter, SN6501-Q1, drives a
center-tapped transformer with an output that is rectified and linearly regulated to provide a stable 5-V supply for
the data converter.
VS
0.1 F
3.3 V
2
Vcc
D2
1:2.2
3
MBR0520L
6,7
OUT
5VISO
13,14
TPS76750-Q1
SN6501-Q1
10 F 0.1 F
D1
1
10 F
GND
IN
GND
5
GND
EN
10 F
3
MBR0520L
5
4
ISO Barrier
1.5 k
1.5 k
1.5 k
0.1 F
1.5 k
5VISO
0.1 F
0.1 F
43
1
VDD
41
40
SDA 2
2
TMS320F28035PAGQ SCL 3
3
X1
X2
VCC1
VCC2
SDA1
VDD
7
SDA2
ISO1541-Q1
6
SCL1
SCL2
GND1
VSS
42
8
8
4
9
10
1
GND2
4
AIN0
SDA
4 Analog
Inputs
ADS1115-Q1
SCL
ADDR
5
AIN3
GND
3
7
Copyright © 2016, Texas Instruments Incorporated
Figure 8-4. Isolated I2C Data Acquisition System
8.2.1 Design Requirements
The recommended power supply voltages (VCC1 and VCC2) must be from 3 V to 5.5 V. A recommended
decoupling capacitor with a value of 0.1 µF is required between both the VCC1 and GND1 pins, and the VCC2
and GND2 pins to support of power supply voltages transient and to ensure reliable operation at all data rates.
8.2.2 Detailed Design Procedure
The power-supply capacitor with a value of 0.1-µF must be placed as close to the power supply pins as possible.
The recommended placement of the capacitors must be 2-mm maximum from input and output power supply
pins (VCC1 and VCC2).
The maximum load permissible on the input lines, SDA1 and SCL1, is ≤ 40 pF and on the output lines, SDA2
and SCL2, is ≤ 400 pF.
The minimum pullup resistors on the input lines, SDA1 and SCL1 to VCC1 must be selected in such a way that
input current drawn is ≤ 3.5 mA. The minimum pullup resistors on the input lines, SDA2 and SCL2, to VCC2
must be selected in such a way that output current drawn is ≤ 35 mA. The maximum pullup resistors on the input
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Product Folder Links: ISO1540-Q1 ISO1541-Q1
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ISO1540-Q1, ISO1541-Q1
www.ti.com
SLLSEX0D – NOVEMBER 2016 – REVISED DECEMBER 2022
lines (SDA1 and SCL1) to VCC1 and on output lines (SDA1 and SCL1) to VCC2, depends on the load and rise
time requirements on the respective lines.
ISO154 0-Q1
2mm
maximu m
2 mm
maximu m
VCC1
VCC2
1k
SDA1
0.1 F
Isol atio n Capa citor
1k
8
1
0.1 F
2
SCL1
3
1k
1k
SDA2
7
SCL2
6
GND2
GND1
4
5
Side 1
Side 2
Figure 8-5. Typical ISO1540-Q1 Circuit Hookup
ISO154 1-Q1
2mm
maximu m
2 mm
maximu m
VCC1
VCC2
1k
SDA1
0.1 F
Isol atio n Capa citor
1k
8
1
0.1 F
2
SCL1
3
1k
1k
SDA2
7
SCL2
6
GND2
GND1
4
5
Side 1
Side 2
Figure 8-6. Typical ISO1541-Q1 Circuit Hookup
8.2.3 Application Curve
o
500 mV/div
TA = 25 C
VCC1 = 3.6 V
900 mV
VOL1
GND1
Time - 50 ns/div
Figure 8-7. Side 1: Low-to-High Transition
24
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Product Folder Links: ISO1540-Q1 ISO1541-Q1
ISO1540-Q1, ISO1541-Q1
www.ti.com
SLLSEX0D – NOVEMBER 2016 – REVISED DECEMBER 2022
9 Power Supply Recommendations
To help ensure reliable operation at data rates and supply voltages, TI recommends connecting a 0.1-µF bypass
capacitor at the 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 TI's SN6501-Q1 device.
For such applications, detailed power supply design and transformer selection recommendations are available in
SN6501-Q1 Transformer Driver for Isolated Power Supplies (SLLSEF3).
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Product Folder Links: ISO1540-Q1 ISO1541-Q1
25
ISO1540-Q1, ISO1541-Q1
www.ti.com
SLLSEX0D – NOVEMBER 2016 – REVISED DECEMBER 2022
10 Layout
10.1 Layout Guidelines
A minimum of four layers is required to accomplish a low EMI PCB design (see Figure 10-1). Layer stacking
should be in the following order (top-to-bottom): high-speed signal layer, ground plane, power plane and lowfrequency 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 100 pF/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 or 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 the Digital Isolator Design Guide (SLLA284)
10.1.1 PCB Material
For digital circuit boards operating at less than 150 Mbps, (or rise and fall times greater than 1 ns), and trace
lengths of up to 10 inches, use standard FR-4 UL94V-0 printed circuit board. This PCB is preferred over cheaper
alternatives because of lower dielectric losses at high frequencies, less moisture absorption, greater strength
and stiffness, and the self-extinguishing flammability-characteristics.
10.2 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 10-1. Recommended Layer Stack
26
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Product Folder Links: ISO1540-Q1 ISO1541-Q1
ISO1540-Q1, ISO1541-Q1
www.ti.com
SLLSEX0D – NOVEMBER 2016 – REVISED DECEMBER 2022
11 Device and Documentation Support
11.1 Documentation Support
Note
TI is transitioning to use more inclusive terminology. Some language may be different than what you
would expect to see for certain technology areas.
11.1.1 Related Documentation
For related documentation see the following:
•
•
•
•
•
•
Digital Isolator Design Guide (SLLA284)
TI Isolation Glossary (SLLA353)
SN6501-Q1 Transformer Driver for Isolated Power Supplies. (SLLSEF3)
TPS767xx-Q1 Fast-Transient-Response 1-A Low-Dropout Voltage Regulators (SGLS009)
ADS1115-Q1 Low-Power, 16-Bit Analog-to-Digital Converter With Internal Reference (SBAS563)
TMS320F2803x Piccolo™ Microcontrollers (TMS320F2803x Piccolo™ Microcontrollers)
11.2 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 11-1. Related Links
PARTS
PRODUCT FOLDER
SAMPLE & BUY
TECHNICAL
DOCUMENTS
TOOLS &
SOFTWARE
SUPPORT &
COMMUNITY
ISO1540-Q1
Click here
Click here
Click here
Click here
Click here
ISO1541-Q1
Click here
Click here
Click here
Click here
Click here
11.3 Receiving Notification of Documentation Updates
To receive notification of documentation updates, navigate to the device product folder on ti.com. In the upper
right corner, click on Alert me to register and receive a weekly digest of any product information that has
changed. For change details, review the revision history included in any revised document.
11.4 Community Resources
11.5 Trademarks
Piccolo™ is a trademark of Texas Instruments.
All trademarks are the property of their respective owners.
12 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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Product Folder Links: ISO1540-Q1 ISO1541-Q1
27
PACKAGE OPTION ADDENDUM
www.ti.com
5-Apr-2022
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)
ISO1540QDQ1
ACTIVE
SOIC
D
8
75
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 125
I1540Q
ISO1540QDRQ1
ACTIVE
SOIC
D
8
2500
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 125
I1540Q
ISO1541QDQ1
ACTIVE
SOIC
D
8
75
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 125
I1541Q
ISO1541QDRQ1
ACTIVE
SOIC
D
8
2500
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 125
I1541Q
(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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