Over Current Protection for PFM Control DC-DC Converter

Kouhei YAMADA  Satoshi SUGAHARA  Nobuo FUJII 

Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences  Vol.E92-A  No.5  pp.1301-1307
Publication Date: 2009/05/01
Online ISSN: 1745-1337
Print ISSN: 0916-8508
Type of Manuscript: PAPER
Category: Analog Signal Processing
Keyword: 
DC-DC converter,  PFM,  over current protection,  bottom current limiting, 

Full Text: PDF(652.4KB)

Summary: 
An over current protection method suitable for Fixed ON-time PFM (Pulse Frequency Modulation) Control DC-DC converters is proposed. It is based on inductor bottom current limiting, realized by monitoring the synchronous rectifier current and extending the OFF-phase of the main switch until it decreases to a predetermined limit, and can properly limit the output current even in case of short circuit. A Fixed ON-time PFM DC-DC converter with the proposed over current protection was designed and fabricated in CMOS IC. Its current limiting operation was verified with simulations and measurements.