Power transistors, drivers, controllers energize diverse array of products

Feb. 20, 2018

The Special Report on page 6 of this issue covers power supplies and loads and also offers coverage of products and technologies expected to be highlighted at APEC 2018, March 4-8 in San Antonio, TX. This Product Focus takes a look at some of the transistors, controller ICs, and evaluation boards that can help you efficiently power today’s applications.

Of note is a series of silicon-carbide (SiC) MOSFETs, the latest addition to Littelfuse’s power-semiconductor line. The devices result from what the company describes as an incremental step toward establishing itself in the power-semiconductor industry through taking a majority investment in the SiC development company Monolith Semiconductor last March. The LSIC1MO120E0080 Series is the first organically designed, developed, and manufactured SiC MOSFET to be released by this partnership.

“Our new SiC MOSFET Series is a critical milestone in our journey to become a leading component supplier in the power semiconductor industry,” said Michael Ketterer, product marketing manager for power semiconductors at Littelfuse. “Our SiC MOSFET application support network is prepared to help customers enhance the performance of their existing designs, as well as assist those developing new power converter products.” Typical applications for these new SiC MOSFETs include power-conversion systems such as solar inverters, switch-mode power supplies, UPS systems, motor drives, high-voltage DC/DC converters, battery chargers, and induction heating.

Other application areas for the products described below range from automotive to consumer electronics. Addressing the latter is an LLC controller from Texas Instruments. “The consumer electronics market demands efficient power supplies with low standby power. With this new family of LLC controllers, TI is enabling designers to do more with less power,” said Steve Lambouses, TI vice president, High Voltage Power. “The UCC256301 was designed to meet tomorrow’s power requirements by delivering breakthroughs in standby power and efficiency while simplifying design and lowering system cost.”

For automotive applications, Melexis has announced new fan driver ICs. “Cooling has always been an enabler for innovation,” Dirk Leman, fan drivers product line manager, said. “As more electronics are integrated into cars, there is a growing need for automotive fans. These new drivers from Melexis ensure that the fans can be driven quietly and reliably, which consumers expect for in-cabin applications. As these automotive-grade devices are fully integrated with no external components required, it is now possible to utilize the benefits of soft switching in the smallest fan applications.”

LLC resonant controller

The UCC256301 inductor-inductor-capacitor (LLC) resonant controller with an integrated high-voltage gate driver enables the industry’s lowest standby power as well as longer system lifetimes, the vendor reports, adding that the UCC256301 provides a cost-effective system solution that helps meet stringent energy-efficiency standards for a range of AC/DC applications, including digital televisions, gaming adapters, desktop computers and notebook adapters, and power-tool battery chargers. The UCC256301 enables standby power of less than 40 mW when fully regulating the system output.

By achieving a new low in standby power, the controller exceeds European Code of Conduct (CoC) Tier 2 and U.S. Department of Energy (DoE) Level VI efficiency standards and achieves more than 90% efficiency with a 10% load, the company reports. Hybrid hysteretic control, a new patented control method, enables up to 10 times faster transient response and reduces output capacitance by 20%. Texas Instruments

IMS evaluation platform

The Insulated Metal Substrate (IMS) Evaluation Platform provides a flexible, low-cost, high-power development platform for high-efficiency power systems with 3-kW or higher applications. The IMS Evaluation Platform, in combination with GaNPX packaging technology and smart design techniques, enables power engineers to quickly take full advantage of GaN power transistors in designing smaller, lighter, lower cost, and more efficient power systems for datacenter, automotive, and energy-storage system applications.

This evaluation platform consists of a motherboard (GSP65MB-EVB) and two IMS evaluation modules in half-bridge and full-bridge variants. The modules can be configured as a half-bridge (single IMS module) or a full bridge (two IMS modules) on the high-power motherboard. IMS evaluation modules are available in two power levels: 3 kW and 6 kW. The IMS evaluation module includes GaN E-HEMTs, gate drivers, isolated DC/DC supply, DC bus decoupling capacitors, and a heatsink to form a fully functional half-bridge power stage.

Platform benefits include low thermal resistance and an optimized layout. The drive board is tightly coupled with the IMS board to minimize power commutation and gate-driver loops to optimize performance. GaN Systems

Automotive-grade fan driver ICs

The US168KLD and US169KLD are automotive grade single-chip solutions for driving single-coil brushless DC fans and motors. As a result of their soft-switching characteristics, they ensure low levels of EMI and acoustic noise, making them suitable for in-cabin automotive applications such as sensor fans as well as other applications such as cooling fans for wireless chargers, computing, audio, and multimedia.

Configured as a full-bridge driver with the ability to drive motor currents up to 300 mA and a supply range from 1.8 V to 5 V, the devices include a sensitive integrated Hall-effect sensor. Built-in reverse voltage, locked rotor, and thermal protection ensure that the drivers are robust, even in challenging applications.

These fan drivers will be qualified to AEC-Q100, ensuring that they are reliable in the most stringent applications. Melexis

750-W CW RF transistor

The MRF13750H/MRF13750HS RF power LDMOS transistors, available in bolt-down and solder-down styles, are 750-W continuous-wave transistors designed for industrial, scientific, and medical (ISM) applications in the 700- to 1,300-MHz frequency range. They are capable of CW or pulse power in narrowband operations.

The transistors are internally input-matched, can be used single-ended or in a push-pull configuration, and are characterized for 30 V to 50 V. They are suitable for linear applications with appropriate biasing and include integrated ESD protection.

The MRF13750H/HS devices offer ease-of-use to microwave generator designers, delivering precision, control, and reliability not available with vacuum-tube-era technologies such as magnetrons.

Typical ISM applications for the MRF13750H/HS include 915-MHz industrial heating and welding systems and 1,300-MHz particle accelerators. An associated test fixture tuned to 915 MHz is available. Manufactured by NXP Semiconductors and available from Richardson RFPD Inc.

3-phase MOSFET driver IC

The A4919 3-phase MOSFET driver IC offers an integrated low-dropout regulator supplying 5 V or 3.3 V and is designed for a range of industrial applications. It can be controlled with block (trapezoidal), sinusoidal, or vector commutation when interfaced with a microprocessor. The A4919 is designed to be a simple direct-control gate driver for both the commercial and industrial markets, providing LDO for peripherals or a microprocessor, and providing complete flexibility over commutation.

A charge-pump regulator provides full (>10-V) gate drive at power-supply voltages down to 7 V and allows the A4919 to operate with reduced gate drive at power-supply voltages down to 5.5 V. A bootstrap capacitor provides the voltage required for the high-side N-channel MOSFETs. One logic-level input is provided for each of the six power MOSFETs in the 3-phase bridge, allowing motors to be driven with any commutation scheme defined by an external controller.

Motor phase short-to-supply and short-to-ground detection is provided by independent drain-source voltage monitors on each MOSFET. Product variants include either 5.0 V or 3.3 V LDO or an option without LDO that instead provides a voltage input that can be used to monitor an external voltage source. Prices each in quantities of 1,000 range from $2.30 to $2.85. Allegro MicroSystems LLC.


The LSIC1MO120E0080 Series SiC MOSFETs, with a voltage rating of 1,200 V and ultralow (80-mΩ) on-resistance, is optimized for high-frequency switching applications, providing a combination of ultralow switching losses and ultrafast switching speeds.

When compared with silicon devices that have the same rating, the SiC MOSFET Series enables greater energy efficiency, reduced system size/weight, and increased power density in power electronics systems, the company said, adding that it also offers robustness and performance even at high operating temperatures (150°C).

The LSIC1MO120E0080 Series SiC MOSFET is available in TO-247-3L packaging and provided in tubes in quantities of 450. Littelfuse Inc.

72-V hybrid step-down DC/DC controller

The LTC7821 hybrid step-down synchronous controller merges a switched capacitor circuit with a synchronous step-down controller, enabling up to a 50% reduction in DC/DC converter solution size compared with traditional step-down solutions, the vendor reports. Other benefits include low EMI and reduced MOSFET stress due to a soft-switched front end, suitable for next-generation nonisolated intermediate bus applications in power-distribution, datacom, and telecom, as well as emerging 48-V automotive systems.

The LTC7821 operates over a 10-V to 72-V input voltage range and can produce an output voltage from 0.9 V to 33.5 V with currents in multiple tens of amps. In a typical 48-V to 12-V/20-A application, an efficiency of 97% is attainable with the LTC7821 switching at 500 kHz. External MOSFETs switch at a fixed frequency programmable from 200 kHz to 1.5 MHz. The LTC7821’s 1-Ω N-channel MOSFET gate drivers can drive multiple MOSFETs in parallel for higher power applications. Multiple LTC7821s can be operated in a parallel, multiphase configuration with current sharing.

An LTC7821-based design eliminates the inrush current typically associated with switched-capacitor circuits. The LTC7821 also monitors system voltage, current, and temperature for faults, and it uses a sense resistor for overcurrent protection. An onboard timer can be set for appropriate restart/retry times. The LTC7821 is available in a 5-mm x 5-mm QFN-32 package. Analog Devices Inc.

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