MIC2846A Datasheet, PDF (1/19 Pages) Micrel Semiconductor – High Efficiency 6 Channel Linear WLED Driver with DAM™, Digital Control and Dual Low IQ LDOs

MIC2846A
High Efficiency 6 Channel Linear WLED
Driver with DAM™, Digital Control and Dual
Low I_Q LDOs
General Description
The MIC2846A is a high efficiency White LED (WLED)
driver featuring two low quiescent current LDOs. It is
designed to drive up to six LEDs and greatly extend
battery life for portable display backlighting and keypad
backlighting in mobile devices. The MIC2846A 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 MIC2846A allows the LEDs to be driven directly
from the battery eliminating switching noise and losses
present with the use of boost circuitry.
The MIC2846A features Dynamic Averaged Matching™
(DAM™) which is specifically designed to get the optimum
matching despite process variations. This ensures a
typical matching of ±1.5% between all six LED channels.
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 MIC2846A also features two independently enabled
low quiescent current LDOs. Each LDO offers ±3%
accuracy over temperature, low dropout voltage (150mV
@ 150mA), and low ground current under all load
conditions (typically 35µA). Both LDOs can be turned off to
draw virtually no current.
The MIC2846A is available in the 2.5mm x 2.5mm 14-pin
Thin MLF^® leadless package with a junction temperature
range of -40°C to +125°C
Datasheet and support documentation can be found on
Micrel’s web site at: www.micrel.com.
Features
WLED Driver
• 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
LDOs
• Very low ground current – Typical 35µA
• Stable with 1µF ceramic output capacitor
• Dropout at 150mV at 150mA
• Thermal shutdown and current limit protection
• Available in a 2.5mm x 2.5mm 14-pin Thin MLF^®
package
Applications
• Mobile handsets
• LCD Handset backlighting
• Handset keypad backlighting
• Digital cameras
• Portable media/MP3 players
• Portable navigation devices (GPS)
• Portable applications
DAM, 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
April 2010
M9999-041210-D