MIC4576 Micrel, Inc.
MIC4576
200kHz Simple 3A Buck Regulator
General Description Features
The MIC4576 is a series of easy to use xed and adjustable Fixed 200kHz operation
BiCMOS step-down (buck) switch-mode voltage regulators. 3.3V, 5V, and adjustable output versions
The 200kHz MIC4576 duplicates the pinout and function of Voltage over specied line and load conditions:
the 52kHz LM2576. The higher switching frequency may Fixed version: 3% max. output voltage
allow up to a 2:1 reduction in output lter inductor size. Adjustable version: 2% max. feedback voltage
Guaranteed 3A switch current
The MIC4576 is available in 3.3V, and 5V xed output ver-
Wide 4V to 36V input voltage range
sions or a 1.23V to 33V adjustable output version. Both
Wide 1.23V to 33V output voltage range
versions are capable of driving a 3A load with excellent line
Requires minimum external components
and load regulation.
< 200A typical shutdown mode
The feedback voltage is guaranteed to 2% tolerance for
75% efciency (adjustable version > 75% typical)
adjustable versions, and the output voltage is guaranteed to
Standard inductors are 25% of typical LM2576 values
3% for xed versions, within specied voltages and load con-
Thermal shutdown
ditions. The oscillator frequency is guaranteed to 10%.
Overcurrent protection
In shutdown mode, the regulator draws less than 200A
100% electrical thermal limit burn-in
standby current. The regulator performs cycle-by-cycle
Applications
current limiting and thermal shutdown for protection under
fault conditions. Simple high-efciency step-down (buck) regulator
Efcient preregulator for linear regulators
This series of simple switch-mode regulators requires a mini-
On-card switching regulators
mum number of external components and can operate using
Positive-to-negative converter (inverting buck-boost)
a standard series of inductors. Frequency compensation is
Battery Charger
provided internally.
Negative boost converter
The MIC4576 is available in TO-220 (T) and TO-263 (U)
Step-down to 3.3V for Intel Pentium
packages for the industrial temperature range.
and similar microprocessors
Typical Applications
L1
5V/3A
5 2
Shutdown
SHDN SW
Enable
33H
MIC4576-5.0WT
8V to 36V
1 4
C2
V FB
IN
1000F
C1
GND
16V
D1
470F
3
MBR360
63V
Fixed Regulator
L1
12V/3A
5 2
Shutdown
SHDN SW
Enable
68H R2
MIC4576WT 13.0k
16V to 36V
4
1
C2
1%
V FB
IN
1000F
C1
GND
R1
16V
470F
MBR360 1.50k
3
63V 1%
Adjustable Regulator
Micrel, Inc. 2180 Fortune Drive San Jose, CA 95131 USA tel + 1 (408) 944-0800 fax + 1 (408) 474-1000 MIC4576 Micrel, Inc.
Ordering Information
Standard RoHS Compliant
Part Number Part Number* Voltage Temperature Range Package
MIC4576-3.3BT MIC4576-3.3WT 3.3V 40C to +85C TO-220-5
MIC4576-5.0BT MIC4576-5.0WT 5.0V 40C to +85C TO-220-5
MIC4576BT MIC4576WT ADJ. 40C to +85C TO-220-5
MIC4576-3.3BU MIC4576-3.3WU 3.3V 40C to +85C TO-263-5
MIC4576-5.0BU MIC4576-5.0WU 5.0V 40C to +85C TO-263-5
MIC4576BU MIC4576WU ADJ. 40C to +85C TO-263-5
* RoHS compliant withhigh-melting solde exemption.
Pin Conguration
5 SHDN
4 FB
3 GND
2 SW
1 V
IN
5-Pin TO-220 (T)
5 SHDN
4 FB
3 GND
2 SW
1 V
IN
5-Pin TO-263 (U)
Pin Description
Pin Number Pin Name Pin Function
1 V Supply Voltage (Input): Unregulated +4V to +36V supply voltage.
IN
2 SW Switch (Output): Emitter of NPN output switch. Connect to external storage
inductor and Shottky diode.
3, TAB GND Ground
4 FB Feedback (Input): Output voltage feedback to regulator. Connect to output
of supply for xed versions. Connect to 1.23V tap of resistive divider for
adjustable versions.
5 SHDN Shutdown (Input): Logic low enables regulator. Logic high (> 2.4V) shuts
down regulator.
MIC4576 2 March 2006
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