MIC2844A View Datasheet(PDF) - Micrel
Part Name
Description
Manufacturer
MIC2844A Datasheet PDF : 14 Pages
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MIC2844A
High Efficiency 6 Channel WLED Driver
with DAM™ and Single Wire Digital Control
General Description
Features
The MIC2844A is a high efficiency linear White LED (WLED)
driver designed to drive up to six WLEDs, greatly extending
battery life for portable display backlighting keypad
backlighting, and camera flash in mobile devices. The
MIC2844A provides the highest possible efficiency as this
architecture has no switching losses present in traditional
charge pumps or inductive boost circuits. The MIC2844A
provides six linear drivers which maintain constant current for
up to six 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.
• 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
The MIC2844A features Dynamic Average Matching™
(DAM™) which is specifically designed to provide optimum
matching across all WLEDs. The six 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.
The MIC2844A is available in the 10-pin 2mm x 2mm Thin
MLF® leadless package with a junction temperature range of
-40°C to +125°C.
Applications
• Mobile handsets
• Handset LCD backlighting
• Handset keypad backlighting
• Camera flash (see MIC2843A datasheet)
• Digital cameras
• Portable media/MP3 players
• Portable navigation devices (GPS)
• Portable applications
Datasheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
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Typical Application
U1 MIC2844AYMT
U1 MIC2844AYMT
VIN
C1
RSET
Low
Dropout
Linear
Driver
DC
Digital
VIN
Control
VIN
C1
RSET
Low
Dropout
Linear
Driver
DC
Digital
Control
LCD Display Backlight with Six 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 +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
August 2009
M9999-080309-D
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