Power Tips #5: Buck-boost design uses a buck controller

Focus:

A buck controller can be used in a buck-boost topology to generate a negative supply voltage from a positive supply voltage. The negative output voltage buck-boost converter, also known as a negative flyback converter, can be run at 50% duty cycle to invert the positive supply. This 2-page Power Tip article describes operation of this converter including its similarities to and differences from the buck converter. The article also discusses input capacitor selection and its placement in the circuit, the need for low ESR caps, and controller requirements. Included here is an example circuit based on the TPS5430, which converts a +12-V input to a -12-V 1-A output.

What you’ll learn:

• How to generate a negative supply voltage from a positive supply using a buck controller
• How to design a negative output voltage buck-boost converter, also known as a negative flyback converter

View the Source

Author & Publication:

Robert Kollman, Texas Instruments, Power Management DesignLine, Nov 04 2008

This article summary appears
in the HOW2POWER Design Guide.

The Design Guide offers
organized access to
hundreds of articles
on dozens of power conversion
and power management topics.

The Design Guide search results
include exclusive summaries
and accurate "how to" analysis
to help you make faster,
more informed decisions.

Search
for more articles