by Timothy Hegarty, Texas Instruments, Phoenix, Ariz., How2Power Today, Mar 15 2016
Focus:
This article tackles the challenge of fitting numerous dc-dc regulators onto a dense system
motherboard to power various high-current loads including FPGAs, ASICs, digital signal
processors (DSPs) and microcontrollers (MCUs). One solution lies in a point-of-load regulator
(POL) module that is designed to parallel stack onto a system motherboard in a mother-daughter
configuration. This article delves into an example of a modular POL implementation with high
density that provides 30 A of output current. This design uses 3D-integrated MOSFETs
(CSD87350Q5D), an efficient shielded inductor, ceramic capacitors and a voltage-mode controller
with integrated gate drivers (the LM27403 sync buck controller). High density (200 A/in3) and a
sub-$5 bill-of-materials cost are the main tenets of this design. The circuit schematic, board
layout and experimental results are presented. Relevant features of the major active and
passive components are outlined. PCB layout considerations are discussed at length.
What you’ll learn:
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