AC/DC regulator enables low standby power in USB chargers

Various features contribute to the superior performance delivered by the AP3785T: a no-load input power rating of less than 10mW; higher efficiency and better EMI result from valley-on operation and a low VCS jitter specification; higher conversion efficiency is also achieved when the AP3785T is used in conjunction with a synchronous rectifier, such as the AP4341. Multiple PWM/PFM control modes further help improve audio noise and efficiency.

Over-voltage protection, output short-circuit protection and transformer saturation protection (via primary peak-current limitation) are all built into the AP3785T. Internal temperature protection is also provided along with a dedicated pin to support external temperature protection. When operating as a constant current regulator, a feedback pin enables compensation for changes in line voltage whereas in constant voltage mode the AP3785T can compensate for voltage drops due to different cable lengths or gauge.