PWM-controller sænker standby forbruget

Fairchild Semiconductors nye primærside PWM controller gør det muligt at reducere standby effektforbruget i USB-ladere (in english).

Designers of power supply applications for portable devices require a USB charger with lower standby power consumption and higher system efficiency in a small form factor. Fairchild Semiconductor’s FAN104W high-frequency primary-side regulation (PSR) PWM controller helps designers meet these challenges.

Incorporating Fairchild’s green-mode function that provides off-time modulation to linearly decrease PWM frequency under light-load conditions, the FAN104W exceeds the USB charger standard with a low standby power of < 30mW and an improved dynamic response of > 4.1V. The FAN104W operates at 85kHz frequency to downsize passive components, assisting in the growing challenge of small form factor requirements. The device can also operate in boundary mode, improving efficiency in full load by 2-3 percent while reducing thermal issues.

Leveraging Fairchild’s expertise in primary-side regulation, the FAN104W does not
require a secondary-side feedback loop and efficiently converts and manages the power supply of the charging device.

Additionally, the device minimizes component count and overall bill-of-material costs with a highly integrated 500V JFET that reduces start-up losses by shutting off the current path after the device has been turned on. It is these optimized features plus rich, integrated protection features such as VSOVP and Vs/Cs, open/short protection that makes the FAN104W a well balanced solution for USB chargers.
http://www.fairchildsemi.com/pf/FA/FAN104W.html