MIC2251 High-Efficiency Low EMI Boost Regulator General Description Features The MIC2251 is a general purpose DC/DC boost switching Over 80% efficient for a 300:1 load range regulator that features low noise, EMI reduction circuitry, 2.5V to 5.5V input voltage range and high efficiency across a wide output current range. Output voltage adjustable to 37V The MIC2251 is optimized for noise-sensitive hand held 52A (typ) quiescent current battery powered applications. A proprietary control method allows low ripple across the output voltage and current Constant peak current control reduces output ripple ranges. The MIC2251 incorporates a pseudo-random EMI reduction circuitry dithering function to reduce EMI levels up to 10dB enabled Stable with small ceramic capacitors by the DITH pin. <1A shutdown current The MIC2251 is designed for use with inductor values from 4.7H to 22H, and is stable with ceramic capacitors from UVLO and thermal shutdown 1F to 22F. 8-pin 2mm x 2mm leadless MLF package (MIC2251) The MIC2251 attains a high peak efficiency up to 90% at 5-pin Thin SOT-23 package (MIC2251-1 & -2) 100mA and excellent light load efficiency of 80% at 1mA. 40 C to +125 C junction temperature range High power density is achieved with the MIC2251s internal 40V/2A rated switch, allowing it to power large loads in a tiny footprint. Applications The MIC2251-1 is available in a 5-pin Thin SOT-23 LCD/OLED display bias supply package with dithering disabled. While the MIC2251-2 is CCD bias supply available in a 5-pin Thin SOT-23 package with dithering Mobile Phones, PDA, Media Players, GPS PND enabled. The MIC2251 is available in a 8-pin 2mm x 2mm MLF leadless package option with an operating junction Haptic displays temperature range of 40C to +125C. Local 5V, 15V, 24V rail Data sheets and support documentation can be found on Micrels web site at: www.micrel.com. Typical Application MLF and MicroLeadFrame are registered trademarks of 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. MIC2251 Ordering Information (1) (3) Part Number Marking Junction Temp. Range Package Lead Finish (2) MIC2251YML 40 to +125C 8-Pin 2mm x 2mm MLF Pb-Free ADA (2) MIC2251-1YD5 DZ1 40 to +125C 5-Pin Thin SOT-23 Pb-Free (2) MIC2251-2YD5 DZ2 40 to +125C 5-Pin Thin SOT-23 Pb-Free Note: 1. Pin 1 identifier = . 2. Over/Underbar ( / ) may not be to scale. 3. MLF is GREEN RoHs compliant package. Lead finish is NiPdAu. Mold compound is Halogen Free. Pin Configuration 8-Pin 2mm x 2mm MLF (ML) 5-Pin Thin SOT-23 (D5) (Top View) (Top View) Pin Description Pin Name Pin Number Pin Number Pin Number Pin Function MIC2251YML MIC2251-1YD5 MIC2251-2YD5 FB 1 3 3 Feedback (Input): 1.24V output voltage sense node. V = 1.24V (1 + R1/R2) OUT AGND 2 Analog Ground. Connect to power ground. PGND 3 2 2 Power Ground. SW 4 1 1 Switch Node (Input): Internal power NMOS drain. NC 5 Not Internally Connected. VIN 6 5 5 Supply (Input): 2.5V to 5.5V input voltage. DITH 7 4 Frequency Dithering (Input): Connect this pin high to enable pseudo-random on-time dithering to reduce EMI. Connect this pin-to-ground to disable this function. EN 8 4 4 Enable (Input): Logic high enables the regulator. Logic low shuts down the regulator. Do not leave floating. HS PAD EP Ground (Return): Exposed backside pad. Connect to power ground. M9999-041811-B April 2011 2