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The “biscuit” charger: engineering ultra-thin

Rongjun ultra-thin GaN charger

Open any ordinary fast charger and you will find the same obstacle: the transformer. It is the tallest component on the board, and it dictates the thickness of the whole product. As long as the transformer stays tall, the charger stays a brick.

The transformer problem

A conventional charger stacks its transformer, capacitors and control circuitry on a compact square board. That layout is cheap and proven, but it sets a hard floor on thickness — usually 28 mm or more. Shaving millimetres off the housing does nothing if the components inside cannot get any flatter.

One piece, not two

Our answer is a proprietary one-piece transformer. By re-engineering the winding structure into a single flat unit, its height drops dramatically — and once the tallest part is flat, the whole board can be re-drawn. We stretch the PCBA into a long, flat, elongated shape. Inside the factory, its outline earned it a nickname: the biscuit.

What the flat board unlocks

  • Chargers as thin as 14.5 mm — close to half the thickness of conventional designs
  • Full-power fast charging with no derating, thanks to GaN efficiency
  • Better heat spreading across the elongated board instead of a hot core
  • A shape that slides between a laptop and its sleeve, or into a shirt pocket

The CB series is where the biscuit design ships today: 45W and 65W ultra-thin chargers, fully certified, available for OEM and ODM programs. If your customers value slim, the biscuit is the strongest hardware story you can put on a shelf.

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