MIC4574_05 Datasheet, PDF (1/7 Pages) Micrel Semiconductor – 200kHz Simple 0.5A Buck Regulator

MIC4574
Micrel, Inc.
MIC4574
200kHz Simple 0.5A Buck Regulator
General Description
The MIC4574 is a series of easy to use fixed and adjustable
BiCMOS step-down (buck) switch-mode voltage regulators.
The 200kHz MIC4574 duplicates the pinout and function of
the 52kHz LM2574. The higher switching frequency may
allow up to a 2:1 reduction in output filter inductor size.
The MIC4574 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 0.5A 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 cur-
rent 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 compensa-
tion is provided internally.
The MIC4574 is available in the DIP (N) package and is rated
over 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 0.5A 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% typ.)
• Standard inductors and capacitors are
25% of typical LM2574 values
• Thermal shutdown
• Overcurrent protection
• 100% electrical thermal limit burn-in
Applications
• Simple high-efficiency step-down (buck) regulator
• Efficient preregulator for linear regulators
• On-card switching regulators
• Positive-to-negative converter (inverting buck-boost)
• Isolated flyback converter using minimum external
components
• Negative boost converter
Typical Application
Shutdown
Enable
8V to 24V
C1
47µF
35V
3 _SHDN
SW ⁷
MIC4574-5.0BN
5 _VIN
FB ¹
SGND PGND
2
4
L1 _5.0V/0.5A
100µH
D1
1N5819
C2
220µF
16V
Fixed Regulator
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 [phone] • fax + 1 [phone] • http://www.micrel.com
June 2005
1
M9999-062105