MIC2845A Datasheet, PDF (1/18 Pages) Micrel Semiconductor – High Efficiency 6 Channel Linear WLED Driver with DAM™, Ultra Fast PWM™ Control and Dual Low IQ LDOs

MIC2845A
High Efficiency 6 Channel Linear WLED
Driver with DAM™, Ultra Fast PWM™
Control and Dual Low I_Q LDOs
General Description
The MIC2845A is a high efficiency White LED (WLED)
driver designed to drive up to six LEDs, greatly extending
battery life for portable display backlighting, keypad
backlighting, and camera flash in mobile devices. The
MIC2845A provides the highest possible efficiency as this
architecture has no switching losses present in traditional
charge pumps or inductive boost circuits. The MIC2845A
provides six linear drivers channels which maintain
constant current for up to six LEDs. It features a typical
dropout of 40mV at 20mA. This allows the LEDs to be
driven directly from the battery eliminating switching
noise/losses present with the use of boost circuitry.
The MIC2845A 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 brightness is
controlled through an Ultra Fast PWM™ Control interface
operating down to less than 1% duty cycle.
The MIC2845A also features two independently enabled
low quiescent current LDOs. Each LDO offers ±3%
accuracy from the nominal voltage over temperature, low
dropout voltage (150mV @ 150mA), and low ground
current under all load conditions (typically 35µA). Both
LDOs can be disabled to draw virtually no current.
The MIC2845A is available in the 14-pin 2.5mm x 2.5mm
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.
Features
WLED Driver
• 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
LDOs
• Very low ground current – Typical 35µA
• Stable with 1µF ceramic output capacitor
• Dropout of 150mV at 150mA
• Thermal shutdown and current limit protection
• Available in a 14-pin 2.5mm x 2.5mm 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 and Ultra Fast PWM 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
April 2010
M9999-041210-C