MIC2570_11 Datasheet, PDF (1/15 Pages) MIC GROUP RECTIFIERS – Two-Cell Switching Regulator

MIC2570
MIC2570
Micrel, Inc.
Two-Cell Switching Regulator
General Description
Micrel’s MIC2570 is a micropower boost switching regulator
that operates from two alkaline, two nickel-metal-hydride
cells, or one lithium cell.
The MIC2570 accepts a positive input voltage between 1.3V
and 15V. Its typical no-load supply current is 130µA.
The MIC2570 is available in selectable fixed output or ad-
justable output versions. The MIC2570-1 can be configured
for 2.85V, 3.3V, or 5V by connecting one of three separate
feedback pins to the output. The MIC2570-2 can be config-
ured for an output voltage ranging between its input voltage
and 36V, using an external resistor network.
The MIC2570 has a fixed switching frequency of 20kHz. An
external SYNC connection allows the switching frequency to
be synchronized to an external signal.
The MIC2570 requires only four components (diode, inductor,
input capacitor and output capacitor) to implement a boost
regulator. A complete regulator can be constructed in a 0.6
in² area.
All versions are available in an 8-lead SOIC with an operating
range from –40°C to +85°.
Features
• Operates from a two-cell supply
1.3V to 15V operation
• 130µA typical quiescent current
• Complete regulator fits 0.6 in² area
• 2.85V/3.3V/5V selectable output voltage (MIC2570-1)
• Adjustable output up to 36V (MIC2570-2)
• 1A current limited pass element
• Frequency synchronization input
• 8-lead SOIC package
Applications
• LCD bias generator
• Glucose meters
• Single-cell lithium to 3.3V or 5V converters
• Two-cell alkaline to ±5V converters
• Two-cell alkaline to –5V converters
• Battery-powered, hand-held instruments
• Palmtop computers
• Remote controls
• Detectors
• Battery Backup Supplies
Typical Applications
2.0V–3.1V
2 AA Cells
C1
100µF
10V
L1
47µH
D1
MB R A 1 4 0
5V/100mA
8
IN
MIC2570-1 ^{SW 1}
2.85V ⁶
3.3V ⁵
5V ⁴
SYNC GND
7
2
C2
220µF
10V
C1
2.5V to 4.2V 100µF
1 Li Cell
10V
L1
1 50µH 2
U1
8
IN
SW ¹
MIC2570
5
3.3V
SYNC GND
7
2
C2
100µF
10V MBRA140
3
D1
L1
V_{O U T}
3.3V/80mA
4
C3
330µF
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 [phone] • fax + 1 [phone] • http://www.micrel.com
August 2007
1
MIC2570