MIC2842A Datasheet, PDF (1/14 Pages) Micrel Semiconductor – High Efficiency 4 Channel WLED Driver with DAM™ and Single Wire Digital Control

MIC2842A
High Efficiency 4 Channel WLED Driver with
DAM™ and Single Wire Digital Control
General Description
Features
The MIC2842A is a high efficiency White LED (WLED)
driver designed to drive up to four LEDs and greatly
extend battery life for portable display backlighting, and
keypad backlighting in mobile devices. The MIC2842A
architecture provides the highest possible efficiency by
eliminating switching losses present in traditional charge
pumps or inductive boost circuits. With a typical dropout of
40mV at 20mA, the MIC2842A allows the LEDs to be
driven directly from the battery eliminating switching noise
and losses present with the use of boost circuitry.
The MIC2842A 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 LED
brightness is preset by an external resistor and can be
dimmed using a single-wire digital control. The digital
interface takes commands from digital programming
pulses to change the brightness in a logarithmic scale
similar to the eye’s perception of brightness. The single-
wire digital brightness control is divided into two modes of
operation; full brightness mode or battery saving mode for
a total of 49 brightness steps.
• High Efficiency (no Voltage Boost losses)
• Dynamic Average Matching™ (DAM™)
• Single wire digital control
• 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
• Camera flash (see MIC2843A datasheet)
• Digital cameras
• Portable media/MP3 players
• Portable navigation devices (GPS)
The MIC2842A is available in the 2mm x 2mm 10-pin Thin
MLF^® leadless package with a junction temperature range
of -40°C to +125°C.
• Portable application
Datasheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
____________________________________________________________________________________________________________
Typical Application
U1 MIC2842AYMT
U1 MIC2842AYMT
V_IN
C1
R_SET
Low
Dropout
Linear
Driver
DC
Digital
Control
GND
V_IN
V_IN
C1
R_SET
Low
Dropout
Linear
Driver
DC
Control
Control
LCD Display Backlight with Four WLEDs
High Current Flash Driver
DAM and Dynamic Average Matching is a trademark 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
August 2009
M9999-080309-D