MIC2571 Micrel MIC2571 Single-Cell Switching Regulator Final Information General Description Features Micrels MIC2571 is a micropower boost switching regulator Operates from a single-cell supply that operates from one alkaline, nickel-metal-hydride cell, or 0.9V to 15V operation lithium cell. 120 A typical quiescent current 2 Complete regulator fits 0.3 in area The MIC2571 accepts a positive input voltage between 0.9V 2.85V/3.3V/5V selectable output voltage (MIC2571-1) and 15V. Its typical no-load supply current is 120 A. Adjustable output up to 36V (MIC2571-2) The MIC2571 is available in selectable fixed output or adjust- 1A current limited pass element able output versions. The MIC2571-1 can be configured for Frequency synchronization input 2.85V, 3.3V, or 5V by connecting one of three separate 8-lead MSOP package feedback pins to the output. The MIC2571-2 can be config- ured for an output voltage ranging between its input voltage Applications and 36V, using an external resistor network. The MIC2571 has a fixed switching frequency of 20kHz. An Pagers external SYNC connection allows the switching frequency to LCD bias generator be synchronized to an external signal. Battery-powered, hand-held instruments Palmtop computers The MIC2571 requires only four components (diode, induc- Remote controls tor, input capacitor and output capacitor) to implement a Detectors boost regulator. A complete regulator can be constructed in 2 Battery Backup Supplies a 0.3 in area. All versions are available in an 8-lead MSOP with an operat- ing range from 40C to +85. Typical Applications D1 D1 L1 L1 150H MBR0530 150H MBR0530 5V/5mA 3.3V/8mA 8 8 IN IN 1 1 SW SW 6 6 C1* C1* 2.85V 2.85V 1V to1.5V 1V to1.5V 47F 47F MIC2571-1 5 MIC2571-1 5 1 Cell 1 Cell 16V 3.3V 16V 3.3V 4 4 5V 5V C2 C2 SYNC GND SYNC GND 47F 47F 7 2 16V 7 2 16V * Needed if battery is 4 from MIC2571 * Needed if battery is 4 from MIC2571 2 2 Circuit size < 0.3 in excluding C1 Circuit size < 0.3 in excluding C1 Single-Cell to 5V DC-to-DC Converter Single-Cell to 3.3V DC-to-DC Converter Micrel, Inc. 1849 Fortune Drive San Jose, CA 95131 USA tel + 1 (408) 944-0800 fax + 1 (408) 944-0970 MIC2571 Micrel Ordering Information Part Number Temperature Range Voltage Frequency Package MIC2571-1BMM 40C to +85C Selectable* 20kHz 8-lead MSOP MIC2571-2BMM 40C to +85C Adjustable 20kHz 8-lead MSOP * Externally selectable for 2.85V, 3.3V, or 5V Pin Configuration MIC2571-1 MIC2571-2 SW 1 8 SW 1 8 IN IN GND 2 7 GND 2 7 SYNC SYNC 3 6 NC 3 6 FB NC 2.85V 5V 4 5 3.3V NC 4 5 NC Adjustable Voltage Selectable Voltage 20kHz Frequency 20kHz Frequency 8-Lead MSOP (MM) 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 MIC2571-1 only. MIC2571 2 1997