资料介绍
There are several ways to convert an AC voltage at a
wall receptacle into the DC voltage required by a
microcontroller. Traditionally, this has been done with a
transformer and rectifier circuit. There are also switch-
ing power supply solutions, however, in applications
that involve providing a DC voltage to only the
microcontroller and a few other low-current devices,
transformer-based or switcher-based power supplies
may not be cost effective. The reason is that the
transformers in transformer-based solutions, and the
inductor/MOSFET/controller in switch-based solutions,
are expensive and take up a considerable amount of
space. This is especially true in the appliance market,
where the cost and size of the components surrounding
the power supply may be significantly less than the cost
of the power supply alone.
Transformerless power supplies provide a low-cost
alternative to transformer-based and switcher-based
power supplies. The two basic types of transformerless
power supplies are resistive and capacitive. This
application note will discuss both with a focus on the
following: AN954
Transformerless Power Supplies: Resistive and Capacitive
Author: Reston Condit
Microchip Technology Inc.
INTRODUCTION
There are several ways to convert an AC voltage at a
wall receptacle into the DC voltage required by a
microcontroller. Traditionally, this has been done with a
transformer and rectifier circuit. There are also switch-
ing power supply solutions, however, in applications
that involve providing a DC voltage to only the
microcontroller and a few other low-current devices,
transformer-based or switcher-based power supplies
may not be cost effective. The reason is that the
transformers in transformer-based solutions, and the
inductor/MOSFET/control
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