MIC2841A Datasheet, PDF (1/13 Pages) Micrel Semiconductor – High Efficiency 4 Channel Linear WLED Driver with DAM™ and Ultra Fast PWM™ Control

MIC2841A
High Efficiency 4 Channel Linear WLED
Driver with DAM™ and Ultra Fast
PWM™ Control
General Description
Features
The MIC2841A is a high efficiency White LED (WLED)
driver designed to drive up to four WLEDs, greatly
extending battery life for portable display backlighting,
keypad backlighting and camera flash in mobile devices.
The MIC2841A provides the highest possible efficiency as
this architecture has no switching losses present in
traditional charge pumps or inductive boost circuits. The
MIC2841A provides four linear driver channels which
maintain constant current for up to four WLEDs. It features
a typical dropout of 40mV at 20mA. This allows the
WLEDs to be driven directly from the battery eliminating
switching noise/losses present with the use of boost
circuitry.
The MIC2841A features Dynamic Average Matching™
(DAM™) which is specifically designed to provide optimum
matching across all WLEDs. The four channels are
matched better than ±1.5% typical, ensuring uniform
display illumination under all conditions. The brightness is
controlled through an Ultra Fast PWM™ interface
operating down to less than 1% duty cycle.
The MIC2841A is available in the 2mm x 2mm 10-pin Thin
MLF^® leadless package with a junction temperature range
of -40°C to +125°C.
Datasheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
• High Efficiency (no Voltage Boost losses)
• Dynamic Average Matching™ (DAM™)
• Ultra Fast PWM™ control (200Hz to 500kHz)
• Input voltage range: 3.0V to 5.5V
• Dropout of 40mV at 20mA
• Matching better than ±1.5% (typical)
• Current accuracy better than ±1.5% (typical)
• Maintains proper regulation regardless of how many
channels are utilized
• Available in a 10-pin 2mm x 2mm Thin MLF^® package
Applications
• Mobile handsets
• Handset LCD backlighting
• Handset keypad backlighting
• Flash driver
• Digital cameras
• Portable media/MP3 players
• Portable navigation devices (GPS)
• Portable applications
____________________________________________________________________________________________________________
Typical Application
U1 MIC2841AYMT
U1 MIC2841AYMT
V_IN
C1
R_SET
Low
Dropout
Linear
Driver
END
PWM
Control
GND
V_IN
C1
V_IN
R_SET
END
PWM
Control
Low
Dropout
Linear
Driver
LCD Display Backlight with Four WLEDs
High Current Flash Driver
Ultra Fast PWM, DAM and Dynamic Average Matching are trademarks of Micrel, Inc.
MLF and MicroLeadFrame are registered trademark Amkor Technology Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel [phone] • fax + 1 [phone] • http://www.micrel.com
June 2009
M9999-062909-C