MIC2171 Datasheet, PDF (1/10 Pages) Micrel Semiconductor – 100kHz 2.5A Switching Regulator Preliminary Information

MIC2171
Micrel
MIC2171
100kHz 2.5A Switching Regulator
Preliminary Information
General Description
Features
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 applications,
the floating switch architecture of the MIC2171 makes it
practical for step-down, inverting, and Cuk configurations 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.
• 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
The MIC2171 is available in a 5-pin TO-220 or TO-263 for Applications
–40°C to +85°C operation.
• Laptop/palmtop computers
• Battery operated equipment
• Hand-held instruments
• Off-line converter up to 50W
(requires external power switch)
• Predriver for higher power capability
4
Typical Applications
+5V
(4.75V min.)
L1
15µH
C1*
47µF
IN
SW
MIC2171
D1
1N5822
V_OUT
+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_OUT
T1
5V, 0.5A
C3*
D2
1N5818
R1
C4 _3.74k
D1*
470µF _1%
1:1.25
L_PRI = 12µH
R2
1.24k
1%
* Optional voltage clipper (may be req’d if T1 leakage inductance too high)
Figure 2.
MIC2171 5V Flyback Converter
1997
4-3