MIC2844AYMT-TR Microchip

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) High Efficiency (no Voltage Boost losses) driver designed to drive up to six WLEDs, greatly extending Dynamic Average Matching (DAM) battery life for portable display backlighting keypad Single wire digital control backlighting, and camera flash in mobile devices. The Input voltage range: 3.0V to 5.5V MIC2844A provides the highest possible efficiency as this architecture has no switching losses present in traditional Dropout of 40mV at 20mA charge pumps or inductive boost circuits. The MIC2844A Matching better than 1.5% (typical) provides six linear drivers which maintain constant current for Current accuracy better than 1.5% (typical) up to six WLEDs. It features a typical dropout of 40mV at Maintains proper regulation regardless of how many 20mA. This allows the WLEDs to be driven directly from the channels are utilized battery eliminating switching noise/losses present with the use of boost circuitry. Available in a 10-pin 2mm x 2mm Thin MLF package The MIC2844A features Dynamic Average Matching Applications (DAM) which is specifically designed to provide optimum matching across all WLEDs. The six channels are matched Mobile handsets better than 1.5% typical, ensuring uniform display Handset LCD backlighting illumination under all conditions. The LED brightness is preset Handset keypad backlighting by an external resistor and can be dimmed using a single- wire digital control. The digital interface takes commands Camera flash (see MIC2843A datasheet) from digital programming pulses to change the brightness in Digital cameras a logarithmic scale similar to the eyes perception of Portable media/MP3 players brightness. The single-wire digital brightness control is divided into two modes of operation full brightness mode, or Portable navigation devices (GPS) battery saving mode for a total of 49 brightness steps. Portable applications The MIC2844A is available in the 10-pin 2mm x 2mm Thin MLF leadless package with a junction temperature range of -40C to +125C. Datasheets and support documentation can be found on Micrels web site at: www.micrel.com. Typical Application U1 MIC2844AYMT U1 MIC2844AYMT V V IN IN C1 Low C1 Low R R SET SET Dropout Dropout Linear Linear Driver Driver V IN DC DC Digital Digital Control 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 Micrel Inc. MIC2844A Ordering Information (1) (2) Part Number Mark Code Temperature Range Package MIC2844AYMT T4Y 40C to +125C 10-Pin 2mm x 2mm Thin MLF Note: 1. Thin MLF S = Pin 1 identifier. 2. Thin MLF is a GREEN RoHS compliant package. Lead finish is NiPdAu. Mold compound is halogen free. Pin Configuration VIN 1 10 D1 DC 2 9 D2 RSET 3 8 D3 GND 4 7 D4 D6 5 6 D5 10-Pin 2mm x 2mm Thin MLF (MT) (Top View) Pin Description Pin Number Pin Name Pin Function 1 VIN Voltage Input. Connect at least 1F ceramic capacitor between VIN and GND. 2 DC Digital control input for linear WLED driver. See Digital Dimming Interface. Do not leave floating. 3 RSET An internal 1.27V reference sets the nominal maximum WLED current. Example, apply a 20.5k resistor between RSET and GND to set LED current to 20mA at 100% duty cycle. 4 GND Ground. 5 D6 LED6 driver. Connect LED anode to VIN and cathode to this pin. 6 D5 LED5 driver. Connect LED anode to VIN and cathode to this pin. 7 D4 LED4 driver. Connect LED anode to VIN and cathode to this pin. 8 D3 LED3 driver. Connect LED anode to VIN and cathode to this pin. 9 D2 LED2 driver. Connect LED anode to VIN and cathode to this pin. 10 D1 LED1 driver. Connect LED anode to VIN and cathode to this pin. EPAD HS PAD Heat sink pad. Not internally connected. Connect to ground. M9999-080309-D August 2009 2