LM2574
Easy Switcher 0.5 A
Step-Down Voltage
Regulator
The LM2574 series of regulators are monolithic integrated circuits
ideally suited for easy and convenient design of a step–down
switching regulator (buck converter). All circuits of this series are
capable of driving a 0.5 A load with excellent line and load regulation.
These devices are available in fixed output voltages of 3.3 V, 5.0 V,
12 V, 15 V, and an adjustable output version.
These regulators were designed to minimize the number of external
components to simplify the power supply design. Standard series of
inductors optimized for use with the LM2574 are offered by several
different inductor manufacturers.
http://onsemi.com
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Since the LM2574 converter is a switch–mode power supply, its
efficiency is significantly higher in comparison with popular
three–terminal linear regulators, especially with higher input voltages.
In most cases, the power dissipated by the LM2574 regulator is so low,
that the copper traces on the printed circuit board are normally the only
heatsink needed and no additional heatsinking is required.
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The LM2574 features include a guaranteed ±4% tolerance on output
voltage within specified input voltages and output load conditions, and
±10% on the oscillator frequency (±2% over 0°C to +125°C). External
shutdown is included, featuring 60 µA (typical) standby current. The
output switch includes cycle–by–cycle current limiting, as well as
thermal shutdown for full protection under fault conditions.
PIN CONNECTIONS
*
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
*
*
*
FB
Output
*
Sig Gnd
Features
V
ON/OFF
in
Pwr Gnd
*
*
*
• 3.3 V, 5.0 V, 12 V, 15 V, and Adjustable Output Versions
• Adjustable Version Output Voltage Range, 1.23 to 37 V ±4% max
over Line and Load Conditions
*
*
(Top View)
• Guaranteed 0.5 A Output Current
• Wide Input Voltage Range: 4.75 to 40 V
• Requires Only 4 External Components
• 52 kHz Fixed Frequency Internal Oscillator
• TTL Shutdown Capability, Low Power Standby Mode
• High Efficiency
1
2
3
4
8
7
6
5
*
FB
Sig Gnd
ON/OFF
Output
*
V
Pwr Gnd
in
(Top View)
• Uses Readily Available Standard Inductors
• Thermal Shutdown and Current Limit Protection
* No internal connection, but should be soldered to
* PC board for best heat transfer.
Applications
• Simple and High–Efficiency Step–Down (Buck) Regulators
• Efficient Pre–regulator for Linear Regulators
• On–Card Switching Regulators
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 24 of this data sheet.
• Positive to Negative Converters (Buck–Boost)
• Negative Step–Up Converters
• Power Supply for Battery Chargers
DEVICE MARKING INFORMATION
See general marking information in the device marking
section on page 24 of this data sheet.
Semiconductor Components Industries, LLC, 2000
1
Publication Order Number:
September, 2000 – Rev. 3
LM2574/D