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器件描述：52kHz Simple 1A Buck Regulator
器件厂商：MICREL [Micrel Semiconductor]
厂商主页：http://www.micrel.com/
文件大小：90.32KB
文件页数：7
PDF阅读：LM2575BT.pdf (点击阅读器件资料)
摘要：
August 1999 1 M2575
LM2575 Micrel
LM2575
52kHz Simple 1A Buck Regulator
General Description
The LM2575 series of monolithic integrated circuits provide
all the active functions for a step-down (buck) switching
regulator. Fixed versions are available with a 3.3V, 5V, 12V,
fixed output. Adjustable versions have an output voltage
range from 1.23V to 37V. Both versions are capable of driving
a 1A load with excellent line and load regulation.
These regulators are simple to use because they require a
minimum number of external components and include internal
frequency compensation and a fixed-frequency oscillator.
The LM2575 series offers a high efficiency replacement for
popular three-terminal adjustable linear regulators. It
substantially reduces the size of the heat sink, and in many
cases no heat sink is required.
A standard series of inductors available from several different
manufacturers are ideal for use with the LM2575 series. This
feature greatly simplifies the design of switch-mode power
supplies.
The feedback voltage is guaranteed to – 2% tolerance for
adjustable versions, and the output voltage is guaranteed to
– 3% for fixed versions, within specified input voltages and
output load conditions. The oscillator frequency is guaranteed
to – 10%. External shutdown is included, featuring less than
200m A standby current. The output switch includes cycle-by-
cycle current limiting and thermal shutdown for full protection
under fault conditions.
870 20
Typical Applications
Features
? 3.3V, 5V, 12V, 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 output current
? Wide input voltage range:
4V to 40V
? Wide output voltage range
1.23V to 37V
? Requires only 4 external components
? 52kHz fixed frequency internal oscillator
? Low power standby mode I
Q
typically < 200m A
? 80% efficiency (adjustable version typically > 80%)
? Uses readily available standard inductors
? Thermal shutdown and current limit 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)
? Isolated Flyback Converter using minimum number of
external components
? Negative Boost Converter
R2
R1
7V–40V
Unregulated
DC Input
LM2575
+
C
IN
100?F
+V
IN
1
3
Gnd
5
On/Off
2
Output
4
Feedback
L1
330?H
+
D1
1N5822
C
OUT
330?F
R2 3.09k
R1 1k
V
OUT
= 1.23 1 +
( )
+5V, 1A
Regulated
Output
Note: Pin numbers are for TO-220 Package
7V–40V
Unregulated
DC Input
LM2575-5.0
+
C
IN
100?F
+V
IN
1
3
Gnd
5
On/Off
2
Output
4
Feedback
L1
330?H
+
D1
1N5822
C
OUT
330?F
+5V, 1A
Regulated
Output
Note: Pin numbers are for TO-220 Package
Fixed Regulator in Typical Application Adjustable Regulator in Fixed Output Application
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