Cirrus Logic AN372 User Manual
An372
Copyright
Cirrus Logic, Inc. 2012
(All Rights Reserved)
Cirrus Logic, Inc.
Application Note
Design Guide for a CS1612 and CS1613
Dimmer-compatible SSL Circuit
1 Overview of the CS1612/13
The CS1612 and CS1613 are digital control ICs engineered to deliver a high-efficiency, cost-effective, flicker-free,
phase-dimmable, solid-state lighting (SSL) solution for the incandescent lamp-replacement market. The CS1612/13
is designed to control a quasi-resonant buck topology. The CS1612 and CS1613 are designed for 120VAC and
230VAC line voltage applications, respectively.
The CS1612/13 integrates a critical conduction mode (CRM) boost converter that provides power factor correction
and dimmer compatibility with a constant output current, quasi-resonant buck stage. An adaptive dimmer
compatibility algorithm controls the boost stage and dimmer compatibility operation mode to enable flicker-free
operation to 2% output current with leading-edge, trailing-edge, and digital dimmers (dimmers with an integrated
power supply).
1.1 Features
• Best-in-class Dimmer Compatibility
- Leading-edge (TRIAC) Dimmers
- Trailing-edge Dimmers
- Digital Dimmers (with Integrated Power Supply)
• Up to 90% Efficiency
• Flicker-free Dimming
• 0% Minimum Dimming Level
• Quasi-resonant Buck Stage with Constant-current Output
- Buck for 1612/13
• Fast Startup
• Tight LED Current Regulation: Better than ±5%
• Primary-side Regulation (PSR)
• >0.9 Power Factor
• IEC-61000-3-2 Compliant
• Soft Start
• Protections:
- Output Open/Short
- Current-sense Resistor Open/Short
- External Overtemperature Using NTC
AN372
AUG’12
AN372REV1