MIC2570 Micrel, Inc. MIC2570 Two-Cell Switching Regulator General Description Features Micrels MIC2570 is a micropower boost switching regulator Operates from a two-cell supply that operates from two alkaline, two nickel-metal-hydride 1.3V to 15V operation cells, or one lithium cell. 130A typical quiescent current 2 Complete regulator ts 0.6 in area The MIC2570 accepts a positive input voltage between 1.3V 2.85V/3.3V/5V selectable output voltage (MIC2570-1) and 15V. Its typical no-load supply current is 130A. Adjustable output up to 36V (MIC2570-2) The MIC2570 is available in selectable xed output or ad- 1A current limited pass element justable output versions. The MIC2570-1 can be congured Frequency synchronization input for 2.85V, 3.3V, or 5V by connecting one of three separate 8-lead SOIC package feedback pins to the output. The MIC2570-2 can be cong- ured for an output voltage ranging between its input voltage and 36V, using an external resistor network. Applications The MIC2570 has a xed switching frequency of 20kHz. An LCD bias generator external SYNC connection allows the switching frequency to Glucose meters be synchronized to an external signal. Single-cell lithium to 3.3V or 5V converters Two-cell alkaline to 5V converters The MIC2570 requires only four components (diode, inductor, Two-cell alkaline to 5V converters input capacitor and output capacitor) to implement a boost Battery-powered, hand-held instruments regulator. A complete regulator can be constructed in a 0.6 2 Palmtop computers in area. Remote controls All versions are available in an 8-lead SOIC with an operating Detectors range from 40C to +85. Battery Backup Supplies Typical Applications C2 L1 D1 100F 47H MBRA140 L1 10V MBRA140 1 50H 2 5V/100mA V OUT 3.3V/80mA 3 8 D1 IN 8 U1 1 2.0V3.1V L1 SW C1 IN MIC2570-1 2 AA Cells 2.5V to 4.2V 1 C1 6 100F SW 4 2.85V 100F 1 Li Cell 10V 5 10V MIC2570 3.3V 5 4 3.3V 5V C2 S YNC GND 220F S YNC GND C3 10V 330F 7 2 7 2 6.3V Two-Cell to 5V DC-to-DC Converter Single-Cell Lithium to 3.3V/80mARegulator Micrel, Inc. 2180 Fortune Drive San Jose, CA 95131 USA tel + 1 (408) 944-0800 fax + 1 (408) 474-1000 MIC2570 Micrel, Inc. Ordering Information Part Number Temperature Range Voltage Frequency Package Standard Pb-Free MIC2570-1BM MIC2570-1YM 40C to +85C Selectable* 20kHz 8-pin SOIC MIC2570-2BM MIC2570-2YM 40C to +85C Adjustable 20kHz 8-pin SOIC * Externally selectable for 2.85V, 3.3V, or 5V Pin Conguration MIC2570-1 MIC2570-2 S W 1 8 SW 1 8 IN IN GND GND 2 7 SYNC 2 7 SYNC 3 6 FB NC 3 6 2.85V NC NC 4 5 NC 5V 4 5 3.3V Adjustable Voltage Selectable Voltage 20kHz Frequency 20kHz Frequency 8-Lead SOIC (M) Pin Description Pin No. (Version ) Pin Name Pin Function 1 SW Switch: NPN output switch transistor collector. 2 GND Power Ground: NPN output switch transistor emitter. 3 NC Not internally connected. 4 (-1) 5V 5V Feedback (Input): Fixed 5V feedback to internal resistive divider. 4 (-2) NC Not internally connected. 5 (-1) 3.3V 3.3V Feedback (Input): Fixed 3.3V feedback to internal resistive divider. 5 (-2) NC Not internally connected. 6 (-1) 2.85V 2.85V Feedback (Input): Fixed 2.85V feedback to internal resistive divider. 6 (-2) FB Feedback (Input): 0.22V feedback from external voltage divider network. 7 SYNC Synchronization (Input): Oscillator start timing. Oscillator synchronizes to falling edge of sync signal. 8 IN Supply (Input): Positive supply voltage input. Example: (-1) indicates the pin description is applicable to the MIC2570-1 only. MIC2570 2 August 2007