Reference design supports development of all-silicon 33W 1C chargers

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Silanna Semiconductor has launched an active clamp flyback (ACF)-based reference design that simplifies and speeds up the development of 33W 1C fast charger applications built using silicon power FETs.

Featuring the company’s latest SZ1131 CO2 Smart Power ACF controller technology, the RD-23 provides a route to delivering performance that matches or exceeds that of commercially available 30W GaN-based chargers at a cost that's more in line with conventional silicon designs.

Silanna’s RD-23 will enable engineer to prototype and develop a fully functional charger with low operational and no-load/ stand-by power consumption and minimum component count, BOM cost and size.

The RD-23 uses the SZ1131 – Silanna Semiconductor’s newest ACF controller, which is rated for 65W for Universal input and above 100W with PFC-supported applications. This controller offers a high level of integration by incorporating an adaptive digital PWM controller, ultra-high-voltage (UHV) active clamp FET, active clamp gate driver and start-up regulator into a single compact device.

Providing an (uncased) power density of 22W/inch3, the RD-23 operates with a peak efficiency of over 92% and has a no-load power consumption (@ 230Vac) below 20mW. Efficiency is flat across the universal input (90 – 265Vac) input range and the reference design is fully production-ready as it exceeds conducted and radiated EMI requirements by more than 6dB margins.

“The RD-23 is the latest in a series of silicon- and GaN-based reference designs that Silanna has created to help engineers quickly and easily develop efficient and high power density chargers,” commented Ahsan Zaman, Silanna Semiconductor’s director of product marketing. “In our benchmarking tests the RD-23 met and exceeded both the efficiency and no-load vampire power consumption of the best-in-class commercially available GaN-based power adapters. RD-23 demonstrates GaN-level performance at silicon-level costs.”

The SZ1131 operates at frequencies of up to 146kHz and provides the ease-of-design of a simple flyback controller with all the benefits of an ACF design. This includes recycling the leakage inductance energy of the flyback transformer and limiting the primary FET drain voltage spike during turn-off events.

Employing Silanna Semiconductor’s OptiMode digital control architecture, the SZ1131 adjusts the device’s mode of operation on a cycle-by-cycle basis to maintain high efficiency, low EMI, fast dynamic load regulation, and other key power supply parameters in response to varying line voltage and load.

Supplied in a 16-pin SOIC package, the SZ1131 offers protection against over-temperature, over-voltage, over-current, over-power and short circuit conditions, as well as transformer core saturation fault without the need for additional external components.