Primary-side switcher raises power supply efficiency

Louise Smyth

Diodes Incorporated has introduced a family of primary‑side power switchers that enables power supply designers to handily achieve the high conversion efficiency needed to meet Energy Star Level 6 and EU CoC Tier 2 requirements. 

Operating up to 80kHz, the AP3983 series employs piecewise Pulse Frequency Modulation (p‑PFM) in discontinuous conduction mode to regulate the primary-side voltage and current to better than ±5% and provide an audible noise-free solution for chargers, ADSL adapters and home appliance power supplies.

As a primary side device with an integrated 650V or 700V BVDSS MOSFET, the AP3983 family eliminates opto-couplers and secondary-side CV/CC control circuitry to minimise external component count. 

Other features include built-in fixed cable voltage-drop compensation, adjustable line-voltage compensation and a range of safety functions, such as, over-voltage and over-temperature protection, and a hiccup function to improve response to short circuits.

A low start-up current (0.6μA, max) combined with a no-load power consumption (75mW, max) and excellent load transient stability all contribute to the high performance offered by the AP3983 switcher, which provides a highly integrated and cost-effective solution for consumer power supplies.

Devices in the AP3983 family support ranges of adapter power ratings (6W to 20W), package types (SO-7 or PDIP-7), and MOSFET voltage ratings (650V or 700V).