Off-line switcher integrates HV transistor for higher charger efficiency

February 23, 2017 // By Graham Prophet
For consumer and industrial applications, with an integrated high-voltage start-up circuit, AP3984 is a high-performance power switcher for line-powered chargers and adaptors. Promising increased conversion efficiency with better voltage and current accuracy, the AP3984 also offers ultra-low power consumption and improved protection functions.

Designed as a primary-side controller, the AP3984 optimises transient characteristics when combined with secondary-side ICs such as the AP4341/2, supplying outputs above 4.3V. This is achieved with current and voltage tolerances of ±5%. The built-in start-up circuit with integrated 700V bipolar junction transistor also eliminates external resistors, simplifying system design and allowing the AP3984 to directly switch the line input. The AP3984 also has a programmable line voltage drop-compensation function.


With protection features such as over-voltage, open- and short-circuit protection, and over-temperature protection (OTP) with auto-restart, the AP3984 provides a highly integrated solution that also meets Energy Star 6.0 efficiency criteria with a standby power of less than 10 mW. Multiple PWM/PFM switching modes combined with a frequency dithering function further aid efficiency while improving EMC performance and reducing audible noise.


In SO-7 package the AP3984MTR-G1 power switcher is priced at $0.27 (1000).


Diodes Inc.;