MIC3289_0706 Datasheet, PDF (1/16 Pages) Micrel Semiconductor – 1.2MHz PWM White LED Driver with Internal Schottky Diode and True 1-Wire Digital Control

MIC3289
1.2MHz PWM White LED Driver with
Internal Schottky Diode and True 1-Wire
Digital Control
General Description
Features
The MIC3289 is a PWM boost-switching regulator that is
optimized for constant-current white LED driver
applications. The MIC3289 features an internal Schottky
diode, allowing an efficient DC/DC solution that requires
only 4 external components.
The MIC3289 allows for a single wire simple digital
interface to control the dimming over 16 steps with a log
scale to give better resolution at the lower currents and to
better match the sensitivity of the human eye. The pre-
programming feature allows the user to select any one of
the 16 WLED current levels as the start-up brightness
level.
The feedback voltage of the MIC3289 is only 250mV,
allowing high efficiency while retaining excellent accuracy
for the white LED current.
• Single wire combines 16 level logarithmic brightness &
shutdown control
• 16V / 24V OVP options supports up to 4 & 6 WLEDs
• Start-up in any one of 16 brightness levels
• Internal Schottky diode
• 2.5V to 6.5V input voltage
• 1.2 MHz PWM operation
• Over 500mA switch current
• 250mV reference voltage
• ±5% LED current accuracy
• <1µA shutdown current
• Over temperature protection
• UVLO
The MIC3289 implements a constant frequency 1.2MHz
PWM control scheme. The high frequency PWM operation
saves board space by reducing external component sizes.
The 1.2MHz PWM scheme also reduces switching noise
and ripple to the input power source.
• Thin SOT23-6L package option
• 2mm × 2mm leadless MLF^®-8L package option
• –40^oC to +125^oC junction temperature range
The 2.5V to 6.5V input voltage range of MIC3289 allows
direct operation from single cell Li Ion as well as 3- to 4-
cell NiCad/NiMH/Alkaline batteries. Battery life is
preserved with a low 1µA shutdown current.
Applications
• White/Blue LED driver for backlighting
- Cell phones
The MIC3289 is available in a low profile Thin SOT23 6-
lead package and a 2mm × 2mm MLF^®-8L package and
has a junction temperature range of –40°C to +125°C.
Data sheets and support documentation can be found on
Micrel’s web site at www.micrel.com.
- PDAs
- GPS systems
- Digital cameras
- Multimedia / MP3 players
• LED flashlights
• Constant current power supplies
___________________________________________________________________________________________________________
MicroLead Frame and MLF are registered trademarks of Amkor Technologies.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel [phone] • fax + 1 [phone] • http://www.micrel.com
June 2007
M9999-061807
[phone]