The Industry’s First Grade 0 Digital Isolator Is Here—And It’s Tailored to Automotive DesignsMarch 03, 2020 by Gary Elinoff
Texas Instruments has designed an automotive quad isolator providing 5,000 VRMS isolation—even up to 150°C.
Texas Instruments has announced that it has designed the "industry's first digital isolator that is qualified to the Grade 0 ambient operating temperature," the ISO7741E-Q1.
TI has emphasized that the device, which qualifies for the Grade 0 ambient operating temperature of the AEC-100 standard, has a high-temperature range, allowing it to operate in automotive environments far hotter than those that AEC-100 Grade 1 devices could survive. These include water pumps, cooling fans, and belt starter generators.
Image used courtesy of Texas Instruments
The ISO7741E-Q1 has three forward and one reverse-direction isolation channels. The logic input and logic output buffers of each separate channel are separated by a double capacitive silicon dioxide insulation barrier.
Simplified schematic of the ISO7741E-Q1. Input supply is VCCI; output supply is VCCO;
input ground is GNDI; output ground is GNDO. Image (modified) used courtesy of Texas Instruments
The unit is equipped with enable pins that can put its associated output in high impedance to reduce power consumption and for multi-master applications. In the event that the signal or input power is lost, the output will go high or low, depending on which device option is chosen.
The ISO7741E-Q1 device is available in a 10.3 mm by 7.6 mm 16-pin SOIC package.
The ISO7741E-Q1 operates with power supplies (VCC) ranging from 2.25 V to 5.5 V. At 1 Mbps, the unit consumes a typical 1.6 mA per channel.
A signal input high and low are registered at 0.7 x VCC, and 0.3 x VCC, respectively.
The data rate is up 100 Mbps. With a 5 V power supply, a typical propagation delay is 10.7 ns.
TI claims that the ISO7741E-Q1 has a projected lifetime of over 100 years at 1,500 VRMS working voltage. Typical common-mode transient immunity (CMTI) is ±100 kV/µs. Surge capability is up to 12.8 kV and the device has an isolation rating of up to 5,000 VRMS isolation rating.
As per IEC 61000-4-2, contact discharge protection across the isolation barrier is ±8 kV.
Controller Area Network Transceiver
Along with the announcement of the digital isolator, TI also announced a controller area network transceiver.
The TCAN1044EV-Q1 is TI’s newest CAN FD (controller area network flexible data rate) transceiver. Like the ISO7741E-Q1, it, too, is an AEC-100 Grade 0-rated device.
It meets the physical layer requirements of the ISO 11898-2:2016 high-speed CAN specification. The new transceiver supports both classical CAN and CAN FD networks at speeds of up to 8 Mbps.
Simplified schematic of TCAN1044EV-Q1. Image used courtesy of Texas Instruments
The TCAN1044EV-Q1 seems to be a logical partner for the ISO7741E-Q1.
A typical application for the CAN FD transceiver would be for a belt starter generator. The ISO7741E-Q1 provides the electrical isolation barrier between an MCU and a CAN (control area network) transceiver, as illustrated below for an older device, the TCAN1043.
Application for a belt starter generator TCAN1043, an earlier iteration of TCAN1044EV-Q1. Image (modified) used courtesy of Texas Instruments
When implementing CAN FD communications in system designs, using the ISO7741E-Q1 can increase the in-vehicle network (IVN) signal protection.
Built for Automotive Designs
TI asserts that ISO7741E-Q1 will find widespread applicability in modern vehicles, including in heating systems and in many types of HVAC subsystems.
In hybrids and EVs, the device can be deployed in battery management systems, traction inverters, and onboard chargers.
Certifications Related to Safety
- UL 1577 component recognition program
- DIN VDE V 0884-11:2017-01 (Germany)
- CSA certification according to IEC 60950-1, IEC 62368-1, IEC 61010-1, and IEC 60601-1 end equipment standards (Canada)
- CQC approval per GB4943.1-2011 (China)
- TUV certification according to EN 60950-1, EN 62368-1 and EN 61010-1 (EEC)
The ISO7741EVM is an evaluation module (EVM) designed to enable users to analyze the ISO7741.
The ISO7741EVM evaluation module. Image used courtesy of Texas Instruments
The ISO7741EVM is richly endowed with numerous jumper options and test points. This, TI says, will enable designers to evaluate the ISO7741 with little need for additional external components.
If you work with automotive designs, have you found temperature limitations to be a thorn in your side? Share your thoughts in the comments below.