MIC4575 Datasheet, PDF (1/12 Pages) Micrel Semiconductor – 200kHz Simple 1A Buck Voltage Regulator

MIC4575
Micrel
MIC4575
200kHz Simple 1A Buck Voltage 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 compensa-
tion is provided internally.
The MIC4575 is available in TO-220 (T) and TO-263 (U)
packages for the industrial temperature range.
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 are
25% of typical LM2575 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)
• Battery Charger
• Negative boost converter
• Step-down 6V to 3.3V for Intel Pentium™
and similar microprocessors
Typical Applications
Shutdown
Enable
8V to 24V
C1
150µF
35V
5 _SHDN
SW ²
MIC4575-5.0BT
1 _VIN
FB ⁴
GND
3
L1
68µH
D1
1N5819
5.0V/1A
C2
330µF
16V
Fixed Regulator
Shutdown
Enable
6V to 24V
C1
22µF
35V
5
SHDN
2
SW
MIC4575BU
1
4
V_IN
FB
GND
3
L1
68µH
R2
2.37k
1%
R1
D1
1.24k
1%
MBRS130LT3
Adjustable Regulator
3.6V/1A
C3
3300pF
C2
330µF
6.3V
4-106
April 1998•