2-Step Power Conversion Datasheet

2-Step Power Conversion Portable Power for the Future

As microprocessor operating voltages continue to decrease, power conversion for CPU core power is becoming a daunting challenge. A core power supply must have fast transient response, good efficiency, and low heat generation in the vicinity of the processor. These factors will soon force a move away from 1-step power conversion from battery or wall adapter to processor, to 2-step conversion where the CPU core power is obtained from the 5V supply. While new to the portable arena, distributed power systems using 5V as a bus voltage have been used in large systems for many years. And although it may not be absolutely necessary to adopt this architecture in portables today, the clock is ticking for the old brute-force approach.

Let’s start with the biggest argument against 2-step conversion the perceived drop in efficiency and attendant heat generation in the 5V supply. Quick calculations may give a false impression that efficiency significantly decreases. It does not! Later in this paper we will show accurate calculations of efficiency for 2-step power conversion based on actual demo board measurements that show overall efficiency numbers equal to 1-step high efficiency converters.

On the other hand, many benefits result from 2-step conversion more symmetrical transient response, lower heat generation in the vicinity of the processor, and easy modification for lower processor voltages in the future. Peak currents taken from the battery are also reduced, which leads to better battery efficiency that can often improve upon the efficiency measured using laboratory power supplies. Consequently, battery life in a real notebook computer may actually exceed that of 1-step architectures.

LTC1628 DUAL OUTPUT DC/DC CONVERTER
LTC1735 OR LTC1736 (VID) DC/DC CONVERTER

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