MIC3287
Micrel, Inc.
MIC3287
1.2MHz
PWM White LED Driver with OVP in
Thin SOT-23 and 2mm x 2mm MFL™
General Description
The MIC3287 is a 1.2MHz pulse width modulated (PWM)
step-up switching regulator that is optimized for constant
current white LED driving applications. With a maximum
output voltage of 24V and a switch current of over 350mA,
the MIC3287 drives a string of up to 4 white LEDs in series,
ensuring uniform brightness and eliminating several ballast
resistors.
The MIC3287 implements a constant frequency 1.2MHz PWM
current-mode control scheme. The high frequency PWM op-
eration saves board space by reducing external component
sizes. The added benefit of the constant frequency PWM
control scheme as opposed to variable frequency control
schemes is much lower noise and input ripple injected back
to the battery source. To optimize efficiency, the feedback
voltage is set to only 250mV. The MIC3287 is also available
with a maximum 24V over-voltage protection.
The MIC3287 is available in low profile Thin SOT-23 5-pin
and Thin SOT-23 6-pin packages. The MIC3287 has a junc-
tion temperature range of –40°C to +125°C.
All support documentation can be found on Micrel’s web site
at: www.micrel.com.
Features
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2.8V to 5.5V Input Voltage
350mA Switch Current
1.2 MHz PWM Operation
250mV Feedback Voltage
24V Output Over-Voltage Protection (OVP) Option
<1% Line and Load Regulation
<1µA Shutdown Current
Over-Temperature Protection
Under-Voltage Lock Out (UVLO)
Low Profile Thin SOT-23-5 Package Option
Low Profile Thin SOT-23-6 Package Option
8-pin 2mm x 2mm MLF™ Package Option
–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
10µH
5
MIC3287YD5
1-Cell
Li Ion
1µF
VIN
EN
SW
FB
GND
2
1
MIC3287-24YD6
6
4
3
0.22µF
250mV
1-Cell
Li Ion
1µF
VIN
EN
SW
OVP
FB
GND
4
1
5
3
4
0.22µF
250mV
3-Series White LED Driver in Thin SOT-23-5
MLF and MicroLeadFrame are trademarks of Amkor Technology, Inc.
4-Series White LED Driver
with Output OVP in Thin SOT-23-6
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
January 2006
1
M9999-010306
MICREL [ MICREL SEMICONDUCTOR ]
