Cirrus Logic AN349 - Manual

Copyright  Cirrus Logic, Inc. 2011
(All Rights Reserved)
http://www.cirrus.com
Application Note
MIGRATING FROM THE L6562 TO THE
CS1601 POWER FACTOR CORRECTION IC
1. Introduction
The CS1601 belongs to Cirrus Logic's family of industry-first digital Power Factor Correction (PFC) ICs offering best-in-class per-
formance. The CS1601 has been optimized for lighting applications. This document compares the CS1601 with the ST Micro-
electronics L6562. A commercially available ballast designed to light two T05HO lamps is used as a benchmark. The test
conditions and setup for the ballast are described in Section 2. The third section of the document details the advantages of using
the CS1601 over the L6562. The fourth section discusses the differences in theory of operation. Section 5 compares the feature
sets of L6562 and CS1601. Section 6 describes a step-by-step procedure to show how to migrate an L6562-based PFC front-
end pre-regulator to a CS1601-based solution.
2. Description of Test Setup
Fluorescent ballasts are a challenging application for PFC due to the presence of large load transients and strict THD require-
ments in a highly cost-sensitive market. Given the wide input voltage range of the application and the demanding form factor
requirements for these applications, many design trade-offs have to be made to complete a design using the current analog Crit-
ical Conduction Mode (CRM) solutions.
2.1 Ballast Specifications & Requirements
- Input Voltage Range: 108V to 305V 50/60Hz
- Output Load: 2x T5HO lamps amounting to ~108W nominal
- Link capacitor: 2x 47
F, 250V caps in series
- Low THD (<10%)
- High Power Factor (>0.9)
- No lamp flicker under any test condition
Lamp
Lamp
Bridge + EMI Filter +
Boost PFC
AC
Input
Figure 1. Example Ballast Second Stage and Lamp Connections
AN349
MAR ‘11
AN349REV1