AP3988

A Product Line of Diodes Incorporated AP3988/89/90 PRIMARY SIDE POWER SWITCHER FOR OFF-LINE SMPS Description The AP3988/89/90 is a performance enhanced power switcher for power supplies with better conversion efficiency, better voltage & current accuracy, and improved protection functions. Typical applications include charger, adapter for ADSL, home appliance power supply, LED lighting power supply and PC auxiliary power supplies. The controller regulates the output voltage and current in the primary side by piece-wise Pulse Frequency Modulation (pPFM) in discontinuous conduction mode (DCM). The system operating frequency reduces linearly from heavy load to light load in each interval of the p-PFM, and enters constant current mode when the load current equals to the maximum system output current. The AP3988/89/90 provides operating frequency dithering function to improve EMC performance of power supply. The AP3988/89/90 also has built-in fixed cable voltage drop compensation (5% of nominal system output voltage) and adjustable line voltage compensation. The AP3988/89/90 solution has fewer component number, smaller size, and lower total cost. The AP3988 is packaged in SO-7. The AP3989/90 is packaged in PDIP-7. Pin Assignments (Top View) CPC FB VCC CS 1 2 3 4 7 GND NEW PRODUCT 6 5 C C SO-7 (M Package) For AP3988 (Top View) CPC FB VCC CS 1 2 3 4 7 GND 6 5 C C PDIP-7 (P7 Package) For AP3989/90 Features          Primary Side Control for Eliminating Opt...