Renesas’ RRW11011 Shrinks 500 W GaN Power Designs with One Chip for PFC and LLC

Designing a high-power AC/DC supply means balancing requirements that are contradictory. Higher power density is expected, mandating that the same wattage fits into a smaller enclosure. Additionally, efficiency and standby-power rules grow stricter with each revision, and EMI and heat must still be managed within that shrinking volume. The control scheme is also typically split between a separate power-factor-correction controller and a separate resonant-converter controller, which increases component count and board area. Renesas Electronics designed its RRW11011 to solve these challenges by combining its interleaved PFC and half-wave LLC digital control into a single primary-side controller, built for compact GaN-based supplies up to 500 W.

Two control jobs in one device

The RRW11011 (Figure 1) is an AC/DC primary-side digital controller that combines an advanced interleaved boost PFC controller with a half-wave LLC converter controller, all in one 16-lead DFN package. Bringing them both under one device’s intelligent digital two-stage control allows coordinating the PFC and resonant stages as a system, rather than as two independently tuned blocks. This coordination helps optimize efficiency while minimizing EMI and audible noise. It also lowers bill of materials (BOM) costs and simplifies the overall layout.

Figure 1: The RRW11011 functional block diagram. (Image source: Renesas)

Why interleaved PFC matters here

The PFC stage uses an interleaved architecture, operating in two staggered switching phases, and utilizing phase-shift control with a 2-phase current-sharing technique to maintain balance. Because the two phases alternate in drawing and delivering current, their ripple currents partially cancel each other, lowering both the input ripple at the line and the output ripple at the bulk capacitor. This partial ripple cancellation pays off in several ways. First, the design can use smaller filter components and magnetics while also lowering EMI, increasing the power density and lowering the overall component count. Additionally, the integrated boost PFC stage improves the power factor and reduces the total harmonic distortion, helping high-power supplies meet line-quality requirements.

The benefits of the half-wave LLC stage

Typically, LLC converters are chosen for their soft switching and high efficiency, and they rely on a main transformer with an auxiliary winding to generate a low-voltage rail to power their internal circuitry. Alternatively, the half-wave LLC design of the RRW11011 employs a patent-pending, direct VHB voltage-sensing technique that eliminates the transformer auxiliary winding, and it uses adaptive zero-voltage switching control and adaptive multi-mode control to keep efficiency high and EMI low across the load range.

Built for GaN switching

The RRW11011 is designed to drive gallium-nitride (GaN) switching devices, and that pairing is where the architecture reaches its highest density at the top of the power band. GaN switches move charge faster and with lower switching loss than silicon, which lets the converter run at a higher frequency. Higher frequency shrinks the transformer and filter components, while the lower switching loss keeps the thermal budget manageable as power climbs toward 500 W. The half-wave LLC stage preserves the soft-switching behavior that keeps resonant converters efficient. Renesas demonstrated the result in a 240 W USB PD EPR power adapter design built on this platform, which achieved a power density of 3 W/cm³ and a peak efficiency of 96.5% at 230 V_AC.

To keep the efficiency high without the wide range working against it, the RRW11011 controller applies adaptive VBULK regulation, adjusting the intermediate bus voltage to current operating conditions rather than holding it fixed, which improves the efficiency and saves energy. On the protection side, the device integrates multiple built-in safeguards, including AC-line brown-out, output short circuit, output overvoltage, and optocoupler failure, among others.

Pairing with the RRW30120 for wide-range output

A high-power primary-side controller still has to deliver a tightly regulated output, and the needs of modern fast charging make that range unusually wide. USB Power Delivery Extended Power Range (EPR) raised the ceiling of USB-C charging to 240 W, or 48 V at 5 A, well beyond the levels older USB-C devices supported. To meet that need, the RRW11011 is optimized to work alongside the RRW30120 (Figure 2), a programmable USB PD controller that manages the Power Delivery protocol and closed-loop output regulation across a 5 to 48 V range.

Figure 2: The RRW30120 functional block diagram. (Image source: Renesas)

Regulating on the secondary side lets the system control the output voltage right where it is delivered, which suits the tight, fast-changing targets of USB Power Delivery. The primary and secondary controllers coordinate across the isolation barrier, so the PFC stage, the resonant stage, and output regulation behave as one system (Figure 3).

Figure 3: A typical application diagram for a USB PD EPR charger. (Image source: Renesas)

Scalable across applications and power levels

The combination of a single integrated primary-side controller, GaN-based switching, and a wide regulated output makes the RRW11011 well suited to rapid-charging AC/DC adapters for phones, tablets, and notebooks, as well as television power, power tools, and e-bikes. It scales with the broader half-wave LLC platform from roughly 100 W up to 500 W.

The RRW11011 is also part of a four-IC family designed to be used together. Alongside the RRW30120, it works with the RRW40120 GaN gate driver and the RRW43110 synchronous rectifier controller. That shared architecture carries across products at different wattages, output voltages, and form factors without the need for a clean-sheet redesign.

Conclusion

For engineers trying to build smaller, cooler, more efficient high-power supplies, the RRW11011 consolidates the control function into one device while serving the wide output range that modern fast-charging needs. Full specifications are detailed on the RRW11011 500 W AC/DC primary-side digital controller product highlight.