Digital Control and GaN HEMTs in 1.2kW Bridgeless Totem-Pole PFC Reference Design

January 11, 2020 by Paul Shepard

The PS-1k2PFC-GaN 1.2 kW Bridgeless Totem Pole PFC (BTP PFC) development platform is controlled by Solantro's latest generation SA4041 digital power processor and leverages the performance benefits of GaN Systems' 650V E-HEMT family.

This fan-less design solution achieves 80 PLUS® Titanium standards for data centers and computing applications.

It demonstrates high power density, reliable start-up, high efficiency, reduced heat sinking, low THD and low EMI. The topology is bi-directional and can be easily scaled (~10kW).

The SA4041 integrates high-speed analog peripherals, hardware accelerators and an event driven timing engine with a 50 MHz micro-processor.

This design implements hysteretic current control with adaptive dead-time control and automatic transition between hard and soft-switched operation (ZVS) to provide maximum efficiency with GaN E-HEMTs over a wide operating range.

The SA4041 integrated hardware accelerators and event timing engine allow the current control loop to be implemented in hardware and allow CPU resources to be utilized for low frequency bulk voltage control, housekeeping and communications functionality.

In this reference design, Solantro's SA4041 uses less than 50% of its available interrupt bandwidth including all control, household, and protection features.

About the Solantro SA4041

The SA4041 is an 80-pin advanced digital power processor. This mixed-signal IC offers a complete set of high-speed analog peripherals, digital accelerators, event control, and digital processing. Industrial, automotive, and renewable energy applications can benefit significantly from the enhanced performance, high power density and reduced component count it offers designers. The SA4041 provides many benefits in advanced topologies for ac-dc power supplies, battery chargers, and dc-dc converters.

The SA4041 is a fully software-programmable digital controller, enabling control, monitoring and optimization through firmware. Solantro bundles application-specific evaluation firmware with specific reference design platforms, allowing customers to achieve faster time-to-market. In addition, Solantro's custom debug environment (Helios) is used to observe and change firmware variables and hardware registers in real-time to expedite the design process.

The SA4041 Advanced Digital Power Processor provides several key advantages over traditional analog or DSP-based digital power controllers:

  • The architecture is power device agnostic (Si MOSFET, SiC, GaN) - allowing customers to optimize cost and performance for a variety of end applications.
  • The rich set of analog and digital power peripherals enables designs with low parts count and maximum power density.
  • Patented digital hardware accelerators eliminate CPU processor burden associated with high-frequency switching control of wide band-gap devices and increase available CPU processing bandwidth for auxiliary system and housekeeping functions.
  • High-performance digital PLL for reliable grid synchronization and start-up
  • Optimizes the efficiency at all power levels by using different control modes: burst, continuous-conduction and transition
  • Variable frequency control minimizes EMI/RFI vs competitive fixed frequency control ICs