MIC4575_09 Datasheet, PDF (1/15 Pages) Micrel Semiconductor – 200kHz Simple 1A Buck Regulator

MIC4575
200kHz Simple 1A Buck Regulator
General Description
The MIC4575 is a series of easy to use fixed and
adjustable BiCMOS step-down (buck) switch-mode voltage
regulators. The 200kHz MIC4575 duplicates the pinout
and function of the 52kHz LM2575. The higher switching
frequency may allow up to a 2:1 reduction in output filter
inductor size.
The MIC4575 is available in 3.3V, and 5V fixed output
versions or a 1.23V to 20V adjustable output version. Both
versions are capable of driving a 1A load with excellent
line and load regulation.
The feedback voltage is guaranteed to ±2% tolerance for
adjustable versions, and the output voltage is guaranteed
to ±3% for fixed versions, within specified voltages and
load conditions. The oscillator frequency is guaranteed to
±10%.
In shutdown mode, the regulator draws less than 200µA
standby current. The regulator performs cycle-by-cycle
current limiting and thermal shutdown for protection under
fault conditions.
This series of simple switch-mode regulators requires a
minimum number of external components and can operate
using a standard series of inductors. Frequency comp-
ensation is provided internally.
The MIC4575 is available in TO-220 (T) and TO-263 (U)
packages for the industrial temperature range.
Data sheets and support documentation can be found on
Micrel’s web site at www.micrel.com.
Features
• Fixed 200kHz operation
• 3.3V, 5V, and adjustable output versions
• Voltage over specified line and load conditions:
• Fixed version: ±3% max. output voltage
• Adjustable version: ±2% max. feedback voltage
• Guaranteed 1A switch current
• Wide 4V to 24V input voltage range
• Wide 1.23V to 20V output voltage range
• Requires minimum external components
• < 200µA typical shutdown mode
• 75% efficiency (adjustable version > 75% typical)
• Standard inductors and capacitors are25% of typical
LM2575 values
• Thermal shutdown
• Overcurrent protection
• 100% electrical thermal limit burn-in
Applications
• Simple high-efficiency step-down (buck) regulator
• Efficient pre-regulator for linear regulators
• On-card switching regulators
• Positive-to-negative converter (inverting buck-boost)
• Battery charger
• Negative boost converter
• Step-down 6V to 3.3V for Intel Pentium^® and similar
microprocessors
___________________________________________________________________________________________________________
Typical Application
Shutdown
Enable
8V to 24V
C1
150µF
35V
5 _SHDN
SW ²
MIC4575-5.0_T
1 _VIN
FB ⁴
GND
3
L1
68µH
D1
1N5819
5.0V/1A
C2
330µF
16V
Fixed Regulator
Adjustable Regulator
Pentium is a registered trademark of Intel Corporation
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel [phone] • fax + 1 [phone] • http://www.micrel.com
July 2009
1
M9999-072909