This design has been developed to address the increasingly complex challenges that are associated with thermal performance in power supplies by offering an innovative combination of features and benefits not seen in other designs.
The PSV-RDAD-65USB reference design combines Pulsiv OSMIUM technology with an industry standard QR flyback and highly optimised, ultra-compact magnetics. It is the first in a series of designs aimed at pushing the boundaries of power conversion by drastically lowering operating temperatures, minimising losses, and reducing size to create a sustainable platform for the USB-C standard.
According to Pulsiv’s Chief Product Officer, Dr Tim Moore, “Our mantra has always been focused on developing solutions that ‘do more while using less’ and this design demonstrates how Pulsiv OSMIUM technology can deliver fast charging without the associated complexity of managing high temperatures.
“The demand for more power and faster charging of cordless products is rapidly increasing which impacts everything from mobile phones to power tools. This means more power is needed in a small form factor which is even more critical when developing in-wall/desk solutions which are sensitive to heat. With 30% lower component temperatures, no inrush current, and high efficiency, we enable designs to become safer, smaller, and be more reliable.”
Above: Pulsiv's half-active bridge control
The Pulsiv OSMIUM reference design delivers 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 33.9°C at 230VAC and 30.3°C at 265V above an ambient temperature of 26.1°C. This sets 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 USB-C connectivity.
Pulsiv OSMIUM technology senses AC line voltage and frequency to adjust capacitor charging time, therefore the circuit draws no line current at the AC zero voltage crossing. This enables a simple half-active bridge implementation to increase efficiency, especially at low line conditions.
In addition, MOSFETs in the lower half of the AC to DC bridge are carefully controlled, in combination with high-side diodes. The half-active bridge in this design delivers a balance between efficiency, cost, and complexity and supports universal input with efficiency gains of 0.7% at full load from a 115V AC supply.
Pulsiv OSMIUM technology generates a HVDC output that varies between the peak AC input and 150V to drive the QR flyback at maximum efficiency. The wider voltage range significantly reduces primary side inductance to enable the use of an EQ20 transformer which was developed in partnership with magnetics experts, Frenetic.
Frenetic’s CEO, Chema Molina commented, “Our team of magnetics experts have demonstrated that Pulsiv OSMIUM technology maximises efficiency and reduces the size of the flyback transformer to a level we’ve not seen before. This significant development will enable customers to improve performance, reduce size, and lower the cost of their design and we’re excited to be part of such an innovative solution. This results in a 20% size reduction and 50% efficiency improvement compared to an RM8 core typically used in other designs.”
GaN transistors from Innoscience have lowered the RDSon and parasitic capacitance to reduce losses and optimise cost in both the flyback and synchronous rectifier sub-systems.
According to General Manager for Innoscience EMEA, Denis Marcon, “We’ve demonstrated that GaN technology is perfectly suited to increasing efficiency, reducing losses, and optimising cost but Pulsiv OSMIUM technology adds further benefits by significantly improving the overall performance and reducing energy waste.”
The PSV-RDAD-65USB document package is available to download free from the Pulsiv website and includes a datasheet, schematics, bill of materials, and Altium files.
The PSV-EBAD-65USB evaluation board enables rapid lab testing and can be pre-ordered for delivery in the second half of August through a network of franchised distribution partners.
