THREE-DIMENSIONAL POWER SUPPLY MODULE HAVING REDUCED SWITCH NODE RINGING

摘要

A high frequency power supply module (800) of a synchronous Buck converter having the control die (810) directly soldered drain-down to the pad (801) of a leadframe; pad (801) is connected to VIN and the VIN connection to control die (810) exhibits vanishing impedance and inductance, thus reducing the amplitude and duration of switch node voltage ringing by more than 90 %. Consequently, the input current enters the control die terminal vertically from the pad. The switch node clip (840), topping the control die (810), is designed with an area large enough to place the sync die (820) drain-down on top of the control die; the current continues to flow vertically through the converter stack. The active area of the sync die is equal to or greater than the active area of the control die; the physical area of the sync die is equal to or greater than the physical area of the control die. The source terminal of sync die (820) is connected to ground by clip (860) designed to act as a heat spreader.