TI moves into solid state relays
Texas Instruments has launched its first solid state relays, aiming at automotive and industrial applications.
“This is a new category for TI to carry power and signals across the isolation barrier in a single chip,” Jeff Morroni at Kilby Labs at TI in Dallas told eeNews. “Compared to mechanical or optoelectronic relays the technologies are well suited to electric vehicles with virtually no wear out, rather than mechanical or discrete transformer.
The solid state relays can disconnect and connect loads through a single isolation barrier in microseconds, compared to milliseconds for electromechanical relays, for safer operation of high-voltage automotive and industrial systems. The devices integrate power and signal transfer in a single chip while also eliminating at least three components from design, reducing the size and cutting the bill of materials (BOM) costs by as much as 50%.
The TPSI3050-Q1 isolated switch driver has an integrated 10V gate supply with 1.5/3A peak source and sink current and up to 50mW supply for external auxiliary circuitry with 5kV isolation. This supports AC or DC switching with seven levels of power transfer via a resistor selection.
It is designed to work with a monitor chip such as the BQ79631-Q1 to detect insulation faults in 800V battery packs. It enables the use of 1MΩ resistors and withstands over 300% more avalanche current than traditional photorelays to help enable safer human-system interaction.
“For the 3050 we use a polymer layer as the separator which gives us 5kVrms, depending on the temperature range and switching cycles,” said Morroni. This isolation allows designers of EV traction inverters to use multiple bias supplies on each leg of the inverter rather than centralised bias isolation.
A drop in replacement, the TSPSI3052-Q2, supports 15V gate drives.
The other device, the TPSI2140-Q1, is a 1400V, 50mA switch with isolation up to 3.75 kVRMS, four times the time-dependent dielectric breakdown reliability of solid-state photorelays.
“The 2140 is more for the isolation check function with the HV switches in the package and can detect whether the barrier is still healthy and we use SiO2 for the isolation,” he said. “This can also be used as an isolated comparator for fault detection in industrial systems.”
“High-voltage systems are becoming more prevalent, especially with the increased adoption of EVs. At TI, we are strongly focused on finding new ways for system designers to solve complex isolation challenges, such as ensuring reliable and safe vehicle operation as the industry transitions to 800-V batteries, while also reducing solution size and cost,” said Troy Coleman, vice president and general manager of Power Switches, Interface and Lighting at Texas Instruments. “By integrating more functionality within our isolation technology, our new solid-state relays enable engineers to reduce the size, cost and complexity of high-voltage power supplies while maintaining the safety of next-generation automotive and industrial systems.”
The TPSI3050-Q1 and TPSI2140-Q1 are available in pre-production, 1,000-unit quantities only on TI.com at US$1.99 and US$2.75, respectively. Designers can evaluate these products with the TPSI3050Q1EVM and TPSI2140Q1EVM evaluation modules, available on TI.com for US$49 each.