MIC2289C_07 Datasheet, PDF (1/9 Pages) Micrel Semiconductor – White LED Driver Internal Schottky Diode and OVP

MIC2289C
White LED Driver Internal Schottky
Diode and OVP
General Description
The MIC2289C is a PWM (pulse width modulated), boost-
switching regulator that is optimized for constant-current
white LED driver applications. The MIC2289C 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 MIC2289C 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 MIC2289C clamps the output voltage in case of open
LED conditions, protecting itself and the output capacitor.
The MIC2289C is available with an output OVP option of
34V.
The MIC2289C is available in low profile 6-pin Thin SOT-
23 package. The MIC2289C 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 with OVP
• Internal Schottky diode
• 1.2 MHz PWM operation
• Over 500mA switch current
• 95mV feedback voltage
• <1% line and load regulation
• <1µA shutdown current
• Overtemperature protection
• UVLO
• Thin SOT-23 6-pin package
• –40°C to +125°C junction temperature range
• For higher performance specifications see the MIC2289
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
MIC2289C-34YD6
VIN SW
1µF
OUT
EN
FB ^95mV
GND
0.22µF/50V
7-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
August 2007
M9999-081507-B