1 Introduction

With the never-ending trend of faster data rates, smaller form factors, and increased power density, board space is becoming gradually scarcer. This makes the job of the power-supply designer increasingly difficult as trying to fulfill all the design requirements, while keeping solution size to a minimum, is no small feat.

One way to go about minimizing the footprint that the power supply leaves on the total design is to choose a converter with a high switching frequency. With higher switching frequencies, design requirements such as output current ripple, output voltage ripple, and load transient can be achieved by using less inductance and output capacitance. This reduces solution size and decreases the total BOM cost of the power supply.

One of the disadvantages of going for higher switching frequencies is increased switching losses. The increased switching losses do not always correlate to decreased efficiency throughout the output current range. It should not be overlooked that switching losses are only one part of the total losses that occur during the operation of a buck converter. As a matter of fact, at higher currents, the conduction losses become the dominant contributor of power loss.

TI’s TPS628512 is a high frequency synchronous buck converter with a small 1.6-mm x 2.1-mm package which provides a small solution size optimized for space constrained applications. Later on in this application note, the TPS628512 will be compared with the TPS54218 to show the impact of conduction losses, in particular, conduction losses in the inductor, on the final efficiency.