AN2829 Datasheet, PDF (1/32 Pages) STMicroelectronics – Dual step-down controller with auxilary voltages

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
February 2009
Rev 1
AM01407v1
1/32
www.st.com