1 Features
• 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 35-
mA 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

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

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.
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 ISO1541-
Q1 has a bidirectional data and a unidirectional clock
channel. The ISO1541-Q1 is useful in applications
that have a single controller while the ISO1540-
Q1 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.