April/May 2021

12 INDUSTRY NEWS Issue 2 2021 Power Electronics Europe www.power-mag.com The 70 m Ω NV6128 represents a 66 % increase in current capability, in a small, 6 x 8 mm PQFN package with a proprietary, integrated cooling pad for high-efficiency, high-density power systems. The NV6128 is rated at 650 V for nominal operation plus a 800 V peak capability for robust operation during transient events. As a power IC, the GaN gate is protected and the device rated at an electrostatic discharge (ESD) specification of 2 kV. “GaNFast power ICs have been broadly adopted by tier-1 names like Lenovo, Dell, OPPO and Xiaomi for fast-charging mobile adapters up to 200 W, with over 13,000,000 shipped and zero failures,” noted Gene Sheridan, Navitas CEO and co-founder. “With the higher-power NV6128, we extended the effective power range to 500 W for the consumer market and look beyond that to multi-kW data center, eMobility and new energy applications.” The NV6128 is in high-volume, mass production by TSMC and available from Navitas’ distribution partners at $7.85 at 1k units. Operating modes When the V CC supply is first applied to the GaNFast power IC, care should be taken such that the V DD and DZ pins are up at their correct voltage levels before the PWM input signal starts. The V DD pin ramp up time is determined by the internal regulator current at this pin and the external CV DD capacitor. C VDD time constant should be calculated such that there is sufficient time to charge up the C VDD capacitor to ~6 V. In some scenarios, where fast startup is required, an optional diode in parallel with the R DD can be used to ensure the C VDD capacitor is fully charged before the first PWM pulse is applied. Also, since the DZ pin voltage sets the V DD voltage level, the V DD pin will ramp up together with the DZ pin (Figure 1). During Normal Operating Mode, all of the internal circuit blocks are active. V CC is operating within the recommended range of 10 V to 24 V, the V DD pin is at the voltage set by the Zener diode at the DZ pin (6.2 V), and the internal gate drive and power FET are both enabled. The Zener voltage is a critical parameter that sets the internal reference for gate drive voltage and other circuitry. The Zener diode needs to be selected such that the voltage on the DZ pin is within recommended operating conditions (5.8 V to 6.6 V) across operating temperature (-40°C to 125°C) and bias current (10 A to 1 mA). To ensure effective operation, the current vs. voltage characteristics of the Zener diode should be measured down to 10 ?A to ensure flat characteristics across the current operating range (10 A to 1 mA). If the Zener selected by user does not ensure that the voltage on the DZ pin is always within the recommended operating range, the functionality and reliability of the GaNFast power IC can be impacted. The external PWM signal at the PWM pin determines the frequency and duty-cycle of the internal gate of the power FET. As the PWM voltage toggles GaNFast IC Delivers 66 Percent More Power NV6128, a new high-power 650 V/800 V-rated GaNFast power IC to address the high-power mobile and consumer power electronics market. Gallium nitride (GaN) is a next-generation semiconductor technology that runs up to 20x faster than Silicon and enables up to 3x more power or 3x faster charging in half the size & weight. GaNFast power ICs integrate GaN power and drive plus protection. Figure 1: Start-up circuit (upper) and LLC half-bridge start-up timing diagram (lower image) Figure 2: Turn-on dV/dt slew rate control