February 2009

Rev 1

1/32

AN2829

Application note

Dual step-down controller with auxilary voltages for

notebook system power

Introduction

The PM6681A is a dual step-down controller with adjustable output voltages that can be

used in notebook power systems. This demonstration board represents a typical application

circuit. The PM6681A demonstration board allows testing of all functions of the device and

provides two switching sections, with (typ.) 1.5 V (OUT1) and 1.05 V (OUT2) outputs from

5.5 V to 28 V input battery voltage. The typical operating switching frequency of the two

sections is 200 kHz/300 kHz, respectively. Each switching section delivers more than 5 A of

output current. An internal linear regulator provides a fixed 5 V output voltage. Another

internal linear regulator provides an adjustable output voltage (default 3.3 V). Both linear

regulators can deliver up to 100 mA peak current.

Figure 1.

PM6681A demonstration board

AM01407v1

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