LM2576/LM2576HV Series SIMPLE SWITCHER 3A Step-Down Voltage Regulator
August 2004
LM2576/LM2576HV Series
SIMPLE SWITCHER
廬
3A Step-Down Voltage Regulator
General Description
The LM2576 series of regulators are monolithic integrated
(buck) switching regulator, capable of driving 3A load with
excellent line and load regulation. These devices are avail-
able in fixed output voltages of 3.3V, 5V, 12V, 15V, and an
adjustable output version.
Requiring a minimum number of external components, these
regulators are simple to use and include internal frequency
compensation and a fixed-frequency oscillator.
The LM2576 series offers a high-efficiency replacement for
popular three-terminal linear regulators. It substantially re-
duces the size of the heat sink, and in some cases no heat
sink is required.
A standard series of inductors optimized for use with the
LM2576 are available from several different manufacturers.
This feature greatly simplifies the design of switch-mode
power supplies.
Other features include a guaranteed
鹵
4% tolerance on out-
put voltage within specified input voltages and output load
conditions, and
鹵
10% on the oscillator frequency. External
shutdown is included, featuring 50 碌A(chǔ) (typical) standby cur-
rent. The output switch includes cycle-by-cycle current limit-
ing, as well as thermal shutdown for full protection under
fault conditions.
Features
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3.3V, 5V, 12V, 15V, and adjustable output versions
n
Adjustable version output voltage range,
1.23V to 37V (57V for HV version)
鹵
4% max over
line and load conditions
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Guaranteed 3A output current
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Wide input voltage range, 40V up to 60V for
HV version
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Requires only 4 external components
n
52 kHz fixed frequency internal oscillator
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TTL shutdown capability, low power standby mode
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High efficiency
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Uses readily available standard inductors
n
Thermal shutdown and current limit protection
n
P+ Product Enhancement tested
Applications
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n
n
n
Simple high-efficiency step-down (buck) regulator
Efficient pre-regulator for linear regulators
On-card switching regulators
Positive to negative converter (Buck-Boost)
Typical Application
Versions)
(Fixed Output Voltage
01147601
FIGURE 1.
SIMPLE SWITCHER
廬
is a registered trademark of National Semiconductor Corporation.
漏 2004 National Semiconductor Corporation
DS011476
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