PMP8583: Can the design support customer's requirements?

Hi Hayashi-san,

The PMP85853 is rated at 6.1W, while the customer requests 10.15W. Generally the UCC28910 can supply up to 6W (application as adapter) and 7.5W (open frame) for universal VAC (90-265VAC), therefore this reference design cannot support it. The UCC28911 in theory can do that, but in open-frame condition (max is 10W).

Please consider also that this converter can reach maximum 115 kHz, but, since it works in variable switching frequency, it will sweep the frequency from ~ 500 Hz (no-load) up to 100 KHz (in order to get some margin) at full load. That means, it is not possible to have in all load conditions Fsw > 100 kHz. If this is a requirement, then we have to select a constant-switching frequency controller, like the LM5021.

Regards,

Roberto

Hi Hayashi-san,

You are correct: when used at high line only, the UCC28911 can support up to 12W in "open frame" application (12W is the maximum continuous power with open frame design at 50°C ambient, with adequate copper area connected on GND pin and /or adequate air flow to have 50°C/W as junction to ambient thermal resistance), and up to 8W for "adapter" application (where 8W is the typical continuous power in enclosed adapter at 50°C ambient, with adequate copper area ( > 560 mm2) connected on GND pin to have
90°C/W as junction to ambient thermal resistance).

Regards,

Roberto