Stacked synchronous buck converter having chip embedded in outside recess of leadframe

摘要

A power supply system (200) has a QFN leadframe with leads and a pad (201, switch node terminal); a pad surface having a portion recessed with a depth (270) and an outline suitable for attaching a semiconductor chip. A first FET chip (220) is vertically stacked to the opposite pad surface. A clip (240) is vertically stacked on the first FET chip and tied to a lead (202, grounded output terminal). A second FET chip (210) has its source terminal attached to the recessed portion and its drain (210a, input terminal) and gate (210b) terminals co-planar with the un-recessed portion. A driver-and-controller chip (230) is attached to the clip. Packaging compound (290) encapsulates the parts but leaves a pad surface and the drain and gate terminals of the second FET chip un-encapsulated.