Cirrus Logic AN379 - Manual

Copyright  Cirrus Logic, Inc. 2014
(All Rights Reserved)
Cirrus Logic, Inc.
http://www.cirrus.com
Application Note
Design Guide for a CS1680 Dimmable
LED Driver IC for Low-voltage Lighting
1 Overview of the CS1680
The CS1680 is a cascade boost-buck dimmable LED driver for the 12V halogen lamp-replacement market. The
CS1680 uses a Cirrus Logic proprietary intelligent digital control that provides exceptional single-lamp and
multi-lamp transformer compatibility for non-dimmer systems and dimmer systems paired with electronic and
magnetic low-voltage transformers.
The CS1680 integrates a continuous conduction mode (CCM) boost converter that provides transformer compati-
bility and dimmer compatibility. An adaptive digital algorithm controls the boost stage and dimmer compatibility
operation mode to enable flicker-free operation down to 5% output current with leading-edge and trailing-edge
dimmers.
1.1 Features
• Best-in-class Transformer Compatibility
- Magnetic Transformers
- Electronic Transformers
• Best-in-class Dimmer Compatibility
- Leading-edge (TRIAC) Dimmers
- Trailing-edge Dimmers
• Up to 80% Efficiency
• Flicker-free Dimming
• 5% Minimum Dimming Level
• Cascade Boost-buck Topology with Constant-current Output
- Output Voltage 15V
• Fast Startup
• Tight LED Current Regulation: Better than ±5%
• >0.9 Power Factor on Magnetic Transformers
• Soft Start
• Protections:
- Output Open/Short
- Boost Overvoltage
- Overcurrent Detection
- External Overtemperature Using NTC
AN379
FEB’14
AN379REV2