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Technical Insight

Magazine Feature
This article was originally featured in the edition:
Issue 3 2024

Discover the path to ultra-cool, compact, and efficient fast charging

News

Introducing the world’s most efficient 65W USB-C reference design from Pulsiv.

BY PULSIV

The demand for USB-C is forecast to surge over the next decade, fuelled by the migration from USB-A to USB-C and a growing market of portable devices that require fast charging. As power requirements increase, the need to deliver more power in a confined space adds challenges with thermal management and heat dissipation which impact safety and reliability.

The PSV-RDAD-65USB reference design has been developed to demonstrate how Pulsiv OSMIUM technology reduces component temperatures, enabling products to consume less power and reduce overall size. It represents the first in a series of designs aimed at pushing the boundaries of power conversion to create a sustainable platform for the USB-C standard.

In this design, the Pulsiv OSMIUM microcontroller PSV-AD-65EG-Q24IV has been combined with OnSemi’s NCP1342 Flyback controller and GaN devices from Innoscience to deliver a world leading specification:

Input Voltage Range
90 – 265VAC (no input voltage derating)
Output Voltage: 5 – 20VDC supporting PD3.0, QC4.0, BC1.2, & PPS (Fast Charging)
Output Power: 65W max
Transformer Temperature: 30.3°C above ambient
Operating Frequency: 125kHz
Peak Efficiency: 96%
Average Efficiency: 95%
Half-Active Bridge: Included
Line Currents: 0.5A max
Inrush Current: Eliminated
GaN Optimised: Yes
DC-DC Converter: Quasi-Resonant (QR) Flyback


Taking ultra-cool operation & fast charging to a whole new level
Critical components in conventional designs will often reach temperatures of over 100°C, so measures must naturally be taken to dissipate heat or limit output power. This means compromising cost, performance, or physical size to mitigate impact safety and reliability issues.

The Pulsiv OSMIUM reference design demonstrates a significant improvement in thermal performance and reduces critical component temperatures by more than 30% compared to other designs. At full load, the Flyback transformer reaches an impressive 33.9°C at 230VAC and 30.3°C at 265V above an ambient temperature of 26.1°C. This incredible achievement is likely to set a new benchmark and enables 65W fast charging in space constrained environments and/or heat sensitive applications such as in-wall plug sockets that incorporate USBC connectivity.



Competitor data demonstrates a highest component temperature of 93.6°C. (A 65W USB-C reference design from a leading manufacturer of power supply solutions.


Setting a new benchmark in power conversion

Pulsiv OSMIUM technology is a patented AC to DC front-end conversion method that applies intelligence to an active valley fill approach and delivers a combination of game changing benefits in power electronics designs. It significantly improves performance at low loads to increase overall average efficiency, reduce energy consumption, and deliver a totally flat efficiency profile across all load conditions.

The Pulsiv AC to DC conversion method intelligently regulates the charging current and voltage on the storage capacitor using a high-side architecture to switch Qch. This allows the use of 200V or 160V capacitors (selectable) to support a universal mains input. The valley-fill period is broadly similar to a 2C3D architecture; but the charging period of the capacitor is significantly longer and more variable.

Reducing system losses
Figure 1 shows a simplified circuit implementation to illustrate the basic operation of Pulsiv OSMIUM technology in this design. A MOSFET, Qch, is used to control the charging of Cch to generate a configurable highvoltage DC output (HVDC) and a blocking diode Db ensures that Cch does not discharge through the body diode of Qch while avoiding stray conduction through the inductor. This approach allows the use of smaller and lower cost 200V or 160V capacitors to support a universal mains input.