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Reliable GaN Switches for Datacenter and Telecom Power

Material Developments

April 10, 2017

Infineon Technologies AG has expanded its GaN power offering with 600V CoolGaN™ 70mOhm and 190mOhm devices designed specifically to maximize the performance benefits and reliability in high-power datacenter server and telecommunications power applications. This latest announcement includes proven power converter design solutions up to 3kW. Infineon is shipping products for early designs and is working with select customers in the targeted application areas.

For these 600V CoolGaN devices, Infineon applied 4 inputs to the qualification plan including failure models to predict useful life and quality level. Those inputs include: Application Profile, Quality Requirement Profile, detailed reliability investigation during device development, and performance degradation models. Using this detailed qualification plan, Infineon has achieved customer target lifetimes and quality levels. For example, lifetime under reverse bias with voltage of 480V with 50% duty cycle and 100 ppm cumulative failure rate is predicted greater than 100 years. Similar lifetime estimates are available for other operating modes/stress conditions. This easily meets a customer need for 15 years of useful life.

“Infineon’s 600V CoolGaN devices are truly reliable and are application qualified for datacenter server and telecommunications power applications,” said Tim McDonald, Senior Director of CoolGaN applications and marketing.

70 mOhm (maximum), 600V rated CoolGAN parts are available with a choice of surface-mount package options: TOLL, 9.9 x 10. 4 x 2.3 mm (L x W x H) and DSO, 20 lead (15.9x11.3.5 mm – L x W x H). The DSO features both bottom side and top side cooled versions. Also available is a 190mOhm maximum device in the TOLL package.

These first products in the new surface-mount 600V CoolGaN family are specifically qualified for truly reliable operation in 1-3 kW datacenter server / telecom applications for highest efficiency and density. The company has demonstrated the performance of these devices in two converter designs. A 2.5kW peak power single phase PFC design that achieves over 99% efficiency and an LLC converter design that achieves over 160 Watts-per-cubic-inch when operated at 350kHz switching frequency with an input voltage of 385-Vac and an output of 52-Vdc.

Using these 600V CoolGaN devices enabled the design of a full-bridge Totem Pole 2.5kW power factor correction stage (230-Vac input and 400-Vdc output) with a flat efficiency curve over 99% across a wide load range. The design is not only efficient, it is simple including: a GaN half-bridge for sync boost where one transistor is the boost switch, the second GaN device is the sync rectifier with the roles of each device swapping with each half-cycle of rectification; and a CoolMOS™ C7 33mΩ device used for line rectification. Benefits of the GaN HEMTs include: zero Qrr for no body-diode recovery losses; rugged commutation characteristics; low gate charge for fast turn-on and turn-off; and these devices are suitable for both hard- and soft-switching.

Infineon also has designed a 3.6kW LLC converter which produces an output of 52-Vdc from a 380V input. This ZVS switching design has an efficiency curve above 98.5% peak (>97.75% from 20 to 100% load) and easily exceeds the Titanium Efficiency standard. The GaN ZVS switches 8X faster than a superjunction device and that means that an 8X shorter dead time is required. Features of this design include: power density of 160W/inch3; 350kHz switching frequency; all power devices in SMD packages contributing to high power density and thermal efficiency; the resulting design is a balanced trade off of high efficiency and high density and is extremely rugged.

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