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Reliable and Affordable Isolation for High-Voltage Designs
Reliable and Affordable Isolation for High-Voltage Designs
Galvanic Isolation:
The Key to Reliability and Safety
Galvanic Isolation: The Key to Reliability and Safety
Basic isolation
Basic isolation
Basic isolation provides basic protection against electric shock and can be achieved by adding insulating barrier tape between polyimide-coated transformer windings, for example.
Galvanic isolation prevents direct currents from flowing from one subcircuit to another. Functional-level isolation facilitates the proper operation of equipment when subcircuits use different voltage domains and operate at different ground potentials. Two additional levels of isolation, basic and reinforced, enhance reliability and safety.
Galvanic isolation prevents direct currents from flowing from a subcircuit to another. Functional-level isolation facilitates the proper operation of equipment when subcircuits use different voltage domains and operate at different ground potentials. Two additional levels of isolation enhance reliability and safety.
Galvanic isolation prevents direct currents from flowing from a subcircuit to another. Functional-level isolation facilitates the proper operation of equipment when subcircuits use different voltage domains and operate at different ground potentials. Two additional levels of isolation enhance reliability and safety.
Reinforced isolation
Reinforced isolation
Reinforced isolation, the highest commercial rating for high-voltage systems, can be achieved by introducing further separation between a transformer’s primary and secondary windings.
Isolation types
Two types of galvanic isolation find use in signal chain and power supply designs: capacitive and magnetic isolation.
Galvanic isolation types
Capacitive isolation
Capacitive isolation exhibits low propagation delay and supports high data rates, but it requires separate bias supply voltages on each side of the isolation barrier.
TI’s capacitive isolation technology
TI employs an SiO2 dielectric that has a high breakdown voltage and is inorganic to provide greater stability over wide temperature and moisture ranges.
Magnetic isolation
Magnetic isolation handles power in excess of hundreds of milliwatts, but it is difficult to increase isolation through winding separation within the confines of an IC.
TI’s magnetic-isolation technology
TI’s unique magnetic technology uses a multichip module approach for transformers to offer either improved coupling or reduced cost/complexity, depending on the application requirements.
Texas Instruments’ Isolation Portfolio
The TI portfolio of isolated signal and power devices helps engineers ensure compliance with the most stringent isolation requirements and offers additional significant benefits:
Higher reliability
Lower system cost
Excellent common-mode transient immunity (CMTI)
Smaller solution sizes
Scalability
Higher reliability
Lower system cost
Excellent common-mode transient immunity (CMTI)
Smaller solution sizes
Scalability
TI: Nearly a quarter of a century of isolation technology innovation
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TI offers a complete isolated-IC portfolio:
Solid-state
relays
relays
Accept a low-power input from a controller IC; produce appropriate high-current gate drive for internal/external power switch.
EXAMPLE
TPSI3050-Q1 automotive reinforced isolated switch driver.
Isolated
comparators
comparators
Provide overcurrent, overvoltage, overtemperature, undervoltage, and zero-crossing detection in high-voltage systems.
EXAMPLE
AMC23C12 reinforced, isolated window comparator with adjustable threshold and latch function.
Isolated DC/DC
converters and modules
converters and modules
Separate a circuit into two sections; prevent direct current flow between input/output.
EXAMPLE
UCC14240-Q1, 1.5-W DC/DC module, providing 3-kVRMS isolation for automotive applications.
Digital
isolators
isolators
Transfer digital signals across a basic or reinforced isolation barrier.
EXAMPLE
ISOW7741 low-emissions, low-ripple, quad-channel, and reinforced digital isolator.
Isolated
gate drivers
gate drivers
Source and sink current at a power-switching device’s gate; protecting from electrical shock.
EXAMPLE
UCC5870-Q1 3.75kVRMS 30A isolated gate driver for IGBT and SiC devices.
Isolated
amplifiers
amplifiers
Deliver analog outputs and can withstand high common-mode voltages.
EXAMPLE
AMC1350-Q1 automotive, ±5-V input, precision, reinforced isolated amplifier for voltage sensing.
Isolated
ADCs
ADCs
Used for high-performance current and voltage sensing applications in high-voltage systems.
EXAMPLE
AMC3306 high-precision, ±50-mV input, reinforced isolated ADC with integrated DC/DC converter.
Isolated
interfaces
interfaces
Simplify the integration and isolation of popular interfaces such as CAN, RS-485, I2C, USB, and LVDS.
EXAMPLE
ISOUSB111 low-emissions, full/low-speed isolated USB repeater.
Isolation applications
- Electric vehicles
- Grid infrastructure
- Factory automation
- Motor drives
To reduce weight and increase efficiency, electric vehicle battery voltages will rise from 400 V to 800 V and higher. To protect personnel and equipment, high-voltage isolation is paramount in battery-management systems, traction inverters, onboard chargers, and other subsystems. Isolated voltage and current sensors, analog-to-digital converters, CAN transceivers, gate drivers, and other components require low-voltage DC bias on both sides of the isolation boundary. TI’s
UCC12051-Q1Opens in a new window. isolated DC/DC power module can deliver this necessary bias. It leverages TI’s integrated magnetic-laminate planar transformer technology to provide up to 500 mW of 3.3-V or 5-V bias while achieving 5-kVRMS isolation. TI’s
ISOW7841A-Q1Opens in a new window. digital isolator,
AMC3336-Q1Opens in a new window. ADC, and
AMC1350-Q1Opens in a new window. amplifier are other devices leveraging TI’s capacitive and magnetic isolation technology for automotive applications.
Grid-connected equipment including solar-energy inverters and electric vehicle chargers can face voltages ranging from 200 V to 1.5 kV or more. Such equipment requires high-voltage insulation, which may deteriorate over time, potentially leading to high-current faults that can cause equipment damage and fatal accidents. An isolated solid-state switch and precision isolated amplifier can monitor insulation performance by performing frequent measurements over decades, providing an alarm when insulation begins to show wear.
TIDA-010232Opens in a new window. reference design describes how to monitor insulation resistance using the
TPSI2140-Q1Opens in a new window. isolated switch and the
AMC3330Opens in a new window. precision isolated amplifier. These devices are available in low-profile SOIC packages and can reduce solution size by up to 50% compared with implementations based on photo relays or mechanical relays.
In today’s automated factory environment, intelligent sensors, actuators, and robots communicate with each other and with outside networks, requiring isolation for power as well as communications and control circuitry. Factory automation applications often employ a programmable logic controller (PLC), which transmits data from field inputs (sensors or transmitters) through an isolator to an MCU. The
ISO1212Opens in a new window. dual-channel isolated 24-V to 60-V digital input receiver combines current-limiting and isolation capabilities in one package to reduce component count, improve performance, and reduce board temperatures in PLC designs. Field transmitters used in factory-automation applications also require isolation and can make use of TI’s ISO70xx digital isolator family, which integrates two to four ultra-low-power channels in small packages while achieving data rates to 4 Mbps.
Motor drives, which power variable-speed motors, typically have two isolation barriers, one between power and control circuits and another between control and interface circuits. Typically, an MCU will generate PWM control signals, and an isolated gate driver provides isolation between the MCU and the power transistors that handle the high voltages and currents that the motor requires. In addition, an isolated amplifier can provide feedback from the power circuitry to the control circuitry. Specific products for motor-drive applications include the
ISO6760LOpens in a new window. digital isolator, which can establish isolation between power and control circuitry, and the
AMC1300Opens in a new window. and AMC1311B isolated amplifiers and AMC1306M25 and AMC1336 isolated modulators, which deliver high-accuracy current and voltage measurements with high common‐mode transient immunity (CMTI) and isolation specifications.
TI Isolated Devices for Safety and Reliability
Texas Instruments offers a complete portfolio of devices that provide capacitive or magnetic galvanic isolation for electric vehicle, grid infrastructure, factory-automation, and motor-drive applications. TI’s SiO2 dielectric for
capacitive devicesOpens in a new window. and unique multichip module approach for
magnetic isolationOpens in a new window. devices ensures the ultimate reliability and safety.
Additional Resources
Increase safety with higher reliability isolation at a lower system cost
Need functional, basic, or reinforced isolation? Start here to find the right isolated power or signal chain IC.
View PortfolioOpens in a new window.Addressing high-voltage design challenges with isolation technology
Get an overview of TI’s isolation technology, as well as practical examples of how magnetic and capacitive isolation are leveraged.
View White PaperOpens in a new window.TI Isolation technology:
Different by design
Different by design
Watch this short video to see what must evolve to keep reliability and affordability at the forefront of isolated designs.
View VideoOpens in a new window.