MIC2842AYMT-TR Microchip

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) High Efficiency (no Voltage Boost losses) driver designed to drive up to four LEDs and greatly Dynamic Average Matching (DAM) extend battery life for portable display backlighting, and Single wire digital control keypad backlighting in mobile devices. The MIC2842A Input voltage range: 3.0V to 5.5V architecture provides the highest possible efficiency by eliminating switching losses present in traditional charge Dropout of 40mV at 20mA pumps or inductive boost circuits. With a typical dropout of Matching better than 1.5% (typical) 40mV at 20mA, the MIC2842A allows the LEDs to be Current accuracy better than 1.5% (typical) driven directly from the battery eliminating switching noise Maintains proper regulation regardless of how many and losses present with the use of boost circuitry. channels are utilized The MIC2842A features Dynamic Average Matching Available in a 10-pin 2mm x 2mm Thin MLF package (DAM) which is specifically designed to provide optimum matching across all WLEDs. The four channels are Applications matched better than 1.5% typical, ensuring uniform display illumination under all conditions. The LED Mobile handsets brightness is preset by an external resistor and can be Handset LCD backlighting dimmed using a single-wire digital control. The digital Handset keypad backlighting interface takes commands from digital programming pulses to change the brightness in a logarithmic scale Camera flash (see MIC2843A datasheet) similar to the eyes perception of brightness. The single- Digital cameras wire digital brightness control is divided into two modes of Portable media/MP3 players operation full brightness mode or battery saving mode for a total of 49 brightness steps. Portable navigation devices (GPS) The MIC2842A is available in the 2mm x 2mm 10-pin Thin Portable application MLF leadless package with a junction temperature range of -40 C to +125 C. Datasheets and support documentation can be found on Micrels web site at: www.micrel.com. Typical Application U1 MIC2842AYMT U1 MIC2842AYMT V V V IN IN IN Low C1 Low C1 R R SET SET Dropout Dropout Linear Linear Driver Driver DC DC Control Digital Control Control GND 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 +1 (408) 944-0800 fax + 1 (408) 474-1000 Micrel Inc. MIC2842A Ordering Information (1) (2) Part Number Mark Code Temperature Range Package MIC2842AYMT R2Y 40C to +125C 10-Pin 2mm x 2mm Thin MLF Note: 1. Thin MLF = 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 N/C 5 6 N/C 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 NC Not connected internally. 6 NC Not connected internally. 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