Order this document by LM2574/D
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.
SEMICONDUCTOR
TECHNICAL DATA
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.
8
1
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.
N SUFFIX
PLASTIC PACKAGE
CASE 626
Features
• 3.3 V, 5.0 V, 12 V, 15 V, and Adjustable Output Versions
PIN CONNECTIONS
• Adjustable Version Output Voltage Range, 1.23 to 37 V ±4% max over
Line and Load Conditions
1
2
3
4
8
7
6
5
*
FB
Sig Gnd
ON/OFF
• Guaranteed 0.5 A Output Current
Output
*
• 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
V
Pwr Gnd
in
(Top View)
* No internal connection, but should be soldered to
* PC board for best heat transfer.
• Uses Readily Available Standard Inductors
• Thermal Shutdown and Current Limit Protection
Applications
DEVICE TYPE/NOMINAL OUTPUT VOLTAGE
LM2574–3.3
LM2574–5
LM2574–12
LM2574–15
LM2574–ADJ
3.3 V
5.0 V
12 V
• Simple and High–Efficiency Step–Down (Buck) Regulators
• Efficient Pre–regulator for Linear Regulators
• On–Card Switching Regulators
• Positive to Negative Converters (Buck–Boost)
• Negative Step–Up Converters
15 V
1.23 V to 37 V
ORDERING INFORMATION
• Power Supply for Battery Chargers
Operating
Temperature Range
Device
Package
LM2574N–XX T = –40° to +125°C
DIP–8
A
XX = Voltage Option, i.e, 3.3, 5, 12, 15 V; and ADJ for
Adjustable Output.
This document contains information on a new product. Specifications and information herein
are subject to change without notice.
Motorola, Inc. 1997
Rev 0