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器件描述：52KHZ SIMPLE 0.5A BUCK REGULATOR
器件厂商：MICREL [Micrel Semiconductor]
厂商主页：http://www.micrel.com/
文件大小：41.98KB
文件页数：8
PDF阅读：LM2574.pdf (点击阅读器件资料)
摘要：
December 2003 1 M9999-122303
LM2574 Micrel
LM2574
52kHz Simple 0.5A Buck Regulator
General Description
The LM2574 family is a series of easy to use fixed and
adjustable switching voltage regulators. The LM2574 con-
tains all of the active circuitry necessary to construct a
stepdown (buck) switching regulator and requires a minimum
of external components.
The LM2574 is available in 3.3V and 5V fixed output versions,
or an adjustable version with an output voltage range of 1.23V
to 37V. Output voltage is guaranteed to ±4% for specified
input and load conditions.
The LM2574 can supply 0.5A while maintaining excellent line
and load regulation. The output switch includes cycle-by-
cycle current limiting, as well as thermal shutdown for full
protection under fault conditions.
An external shutdown connection selects operating or standby
modes. Standby current is less than 200?A.
Heat sinks are generally unnecessary due the regulator’s
high efficiency. Adequate heat transfer is usually provided by
soldering all package pins to a printed circuit board.
The LM2574 includes internal frequency compensation and
an internal 52kHz fixed frequency oscillator guaranteed to
±10% of the frequency.
Circuits constructed around the LM2574 use a standard
series of inductors which are available from several different
manufacturers.
All support documentation can be found on Micrel’s web
site at www.micrel.com.
Typical Application
V
IN
PWR
GND
SIG
GND
ON/
OFF
OUT
FB
LM2574
C
IN
22?F
40V MAX
UNREGULATED
DC IN
REGULATED
OUTPUT
0.5A
11DQ05
C
OUT
220?F
330?H
Figure 1. Fixed Output Regulator Circuit
Features
? 3.3V, 5V, 12V, and adjustable output versions
? Adjustable version output 1.23V to 37V ±4% max. over
line and load conditions.
? Guaranteed 0.5A output current
? Wide input voltage, up to 40V
? Thermal shutdown and current limit protection
? Requires only 4 external components.
? Shutdown capability (standby mode)
? Low power standby mode < 200?A Typical
? High-efficiency
? 52kHz fixed frequency internal oscillator
? Uses standard inductors
Applications
? Simple high-efficiency step-down (buck) regulator
? Efficient pre-regulator for linear regulators
? On-card switching regulators
? Positive to negative converter (buck-boost)
Ordering Information
Part Number Junction Temp. Range Package
LM2574BN –40°C to +85°C 8-pin Plastic DIP
LM2574-3.3BN –40°C to +85°C 8-pin Plastic DIP
LM2574-5.0BN –40°C to +85°C 8-pin Plastic DIP
Micrel, Inc. ? 1849 Fortune Drive ? San Jose, CA 95131 ? USA ? tel + 1 (408) 944-0800 ? fax + 1 (408) 944-0970 ? http://www.micrel.com
相关器件：LM2574-3.3BN LM2574-5.0BN LM2574BN
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