MIC2287
Micrel, Inc.
MIC2287
1.2MHz PWM White LED Driver with OVP in
2mm × 2mm MLF™ and Thin SOT-23
General Description
Features
The MIC2287 is a 1.2MHz pulse width modulated (PWM),
boost-switching regulator that is optimized for constant-
current, white LED driver applications. With a maximum
output voltage of 34V and a switch current of over 500mA,
the MIC2287 easily drives a string of up to 8 white LEDs in
series, ensuring uniform brightness and eliminating several
ballast resistors.
• 2.5V to 10V input voltage
• Output voltage up to 34V
• Over 500mA switch current
• 1.2 MHz PWM operation
• 95mV feedback voltage
• Output Overvoltage Protection (OVP)
• Options for 15V, 24V, and 34V OVP
• <1% line and load regulation
• <1µA shutdown current
• Over-temperature protection
• UVLO
• Low profile Thin SOT-23-5 package option
• 8-lead 2mm × 2mm MLF™ package option
• –40°C to +125°C junction temperature range
The MIC2287 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
as opposed to variable frequency topologies is much lower
noise and input ripple injected back to the battery source.
To optimize efficiency, the feedback voltage is set to only
95mV. This reduces the power dissipation in the current set
resistor and allows the lowest total output voltage, hence
minimal current draw from the battery.
Applications
• White LED driver for backlighting:
- Cell phones
The MIC2287 is available with 3 levels of overvoltage protec-
tion, 15V, 24V, and 34V. This allows designers to choose the
smallest possible external components with the appropriate
voltage ratings for their applications.
- PDAs
- GPS systems
- Digital cameras
- MP3 players
- IP phones
• Photo flash LED driver
• LED flashlights
• Constant current power supplies
TheMIC2287isavailableinlowprofileThinSOT-235-leadand
an8-lead2mm×2mmMLF™packageoptions.TheMIC2287
has a junction temperature range of –40°C to +125°C.
All support documentation can be found on Micrel’s web site
at www.micrel.com.
Typical Application
CMDSH-3
10µH
CMDSH-3
10µH
MIC2287BD5
MIC2287-34BML
5
4
1
3
VIN
SW
VIN
EN
SW
1-Cell
Li Ion
1µF
1-Cell
Li Ion
1µF
0.22µF
OVP
0.22µF
FB
EN
95mV
6.3Ω
FB
95mV
6.3Ω
GND
GND
2
3-Series White LED Driver in Thin SOT-23
6-Series White LED Driver
with Output OVP in 2mm × 2mm MLF™-8
MLF and MicroLeadFrame are trademarks of Amkor Technology, Inc.
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
M9999-070105
July 2005
1