MIC2289 Datasheet, PDF (1/10 Pages) Micrel Semiconductor – 2mm × 2mm White LED Driver with Internal Schottky Diode and OVP

MIC2289
White LED Driver Internal Schottky
Diode and OVP
General Description
The MIC2289 is a PWM (pulse width modulated), boost-
switching regulator that is optimized for constant-current
white LED driver applications. The MIC2289 features an
internal Schottky diode and three levels of output
overvoltage protection providing a small size and efficient
DC/DC solution that requires only four external
components.
To optimize efficiency, the feedback voltage is set to only
95mV. This reduces power dissipation in the current set
resistor and allows the lowest total output voltage, hence
minimal current draw from the battery.
The MIC2289 implements a constant frequency 1.2MHz
PWM control scheme. The high frequency, PWM operation
saves board space by reducing external component sizes.
The added benefit of the constant frequency PWM scheme
in caparison to variable frequency is much lower noise and
input ripple injected to the input power source.
The MIC2289 clamps the output voltage in case of open
LED conditions, protecting itself and the output capacitor.
The MIC2289 is available with three output OVP options of
15V, 24V, and 34V. The different OVP options allows the
use of the smallest possible output capacitor with the
appropriate voltage rating for a given application.
The MIC2289 is available in low profile 6-pin Thin SOT-23
and 8-pin 2mm × 2mm MLF^® package options. The
MIC2289 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.
Features
• 2.5V to 10V input voltage
• Output voltage up to 34V
• Internal Schottky diode
• 15V, 24V, 34V output OVP options
• 1.2 MHz PWM operation
• Over 500mA switch current
• 95mV feedback voltage
• <1% line and load regulation
• <1µA shutdown current
• Overtemperature protection
• UVLO
• 2mm × 2mm 8-pin MLF^® package
• –40°C to +125°C junction temperature range
Applications
• White LED driver for backlighting:
– Cell phones
– PDAs
– GPS systems
– Digital cameras
– MP3 players
– IP phones
• LED flashlights
• Constant current power supplies
Typical Application
10µH
1-Cell
Li Ion
MIC2289-15BML
VIN SW
1µF
OUT
EN
FB ^95mV
GND
0.22µF/16V
3-Series White LED Driver
3-Series LED Efficiency
82
80
78
76
74
72
V_IN =3.6V
700
5 10 15 20 25
I_OUT (mA)
MLF and MicroLeadFrame are registered trademarks of Amkor Technology, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel [phone] • fax + 1 [phone] • http://www.micrel.com
July 2007
M9999-071007