MIC2171_07 Datasheet, PDF (1/12 Pages) Micrel Semiconductor – 100kHz 2.5A Switching Regulator

MIC2171
100kHz 2.5A Switching Regulator
General Description
The MIC2171 is a complete 100kHz SMPS current-mode
controller with an internal 65V 2.5A power switch.
Although primarily intended for voltage step-up applica-
tions, the floating switch architecture of the MIC2171
makes it practical for step-down, inverting, and Cuk config-
urations as well as isolated topologies.
Operating from 3V to 40V, the MIC2171 draws only 7mA
of quiescent current, making it attractive for battery
operated supplies.
The MIC2171 is available in a 5-pin TO-220 or TO-263 for
–40°C to +85°C operation.
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
Features
• 2.5A, 65V internal switch rating
• 3V to 40V input voltage range
• Current-mode operation, 2.5A peak
• Internal cycle-by-cycle current limit
• Thermal shutdown
• Twice the frequency of the LM2577
• Low external parts count
• Operates in most switching topologies
• 7mA quiescent current (operating)
• Fits LT1171/LM2577 TO-220 and TO-263 sockets
Applications
• Laptop/palmtop computers
• Battery operated equipment
• Hand-held instruments
• Off-line converter up to 50W(requires external power
switch)
• Pre-driver for higher power capability
___________________________________________________________________________________________________________
Typical Application
+5V
(4.75V min.)
L1
15µH
C1*
47µF
IN
SW
MIC2171
D1
1N5822
V_{O U T}
+12V, 0.25A
R1
10.7k
1%
COMP
FB
R3
1k
C3
GND
1µF
C2
470µF
R2
1.24k
1%
* Locate near MIC2171 when supply leads > 2”
Figure 1. MIC2171 5V to 12V Boost Converter
V_IN
4V to 6V
C1
R4*
47µF
IN
SW
MIC2171
COMP
FB
R3
1k
GND
C2
1µF
V_{OU T}
T1
5V, 0.5A
C3*
D2
1N5818
R1
C4 _3.74k
D1*
470µF _1%
1:1.25
L_{P RI} = 12µH
R2
1.24k
1%
* Optional voltage clipper (may be req’d if T1 leakage inductance too high)
Figure 2. MIC2171 5VFlyback Converter
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel [phone] • fax + 1 [phone] • http://www.micrel.com
May 2007
1
M9999-051107