33W charger reference design uses silicon mosfets

The active clamp fly-back design, called RD-23, “provides a route to delivering performance that matches or exceeds that of commercially available 30W GaN-based chargers at a cost more readily associated with conventional silicon designs,” claimed the company.

Uncased power density is 22W/inch³, peak efficiency is >92% and no-load power (at 230Vac) is <20mW, according to Silanna, with flat efficiency across 90 to 265Vac, and more that 6dB margin over conducted and radiated EMI requirements – see the design test report to interpret this claim.

“In our benchmarking tests, RD-23 met and exceeded both the efficiency and no-load vampire power consumption of the best-in-class commercially available [30W] GaN-based power adapters.,” said the company marketing director Ahsan Zaman.

SZ1131 operates at up to 146kHz, and adjusts operating mode cycle-by-cycle to balance efficiency, EMI and load regulation in response to varying line voltage and load. It comes in a 16-pin SOIC.

Protection include over-temperature, over-voltage, over-current, over-power, short-circuit and transformer core saturation.

Active clamping recycles leakage inductance energy from the fly-back transformer and limits the primary FET drain voltage spike during turn-off events.

Cased, the design is 39 x 39 x 42mm plus mains connector pins.

The RD-23 reference design report can be found here

Silanna Semiconductor’s HQ is in San Diego, and Silanna Group’s HQ is in Brisbane Australia.