Order this document by LM2574/D
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.
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.
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.
Features
EASY SWITCHER™
0.5 A STEP–DOWN
VOLTAGE REGULATOR
SEMICONDUCTOR
TECHNICAL DATA
16
1
DW SUFFIX
PLASTIC PACKAGE
CASE 751G
(SO–16L)
8
1
N SUFFIX
PLASTIC PACKAGE
CASE 626
(DIP–8)
PIN CONNECTIONS
*
*
FB
Sig Gnd
ON/OFF
Pwr Gnd
*
*
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
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
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
Uses Readily Available Standard Inductors
Thermal Shutdown and Current Limit Protection
*
*
Output
*
Vin
*
*
*
(Top View)
FB
Sig Gnd
ON/OFF
Pwr Gnd
1
2
3
4
8
7
6
5
*
Output
*
Vin
(Top View)
* 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
Positive to Negative Converters (Buck–Boost)
Negative Step–Up Converters
Power Supply for Battery Chargers
DEVICE TYPE/NOMINAL OUTPUT VOLTAGE
LM2574–3.3
LM2574–5
LM2574–12
LM2574–15
LM2574–ADJ
3.3 V
5.0 V
12 V
15 V
1.23 V to 37 V
ORDERING INFORMATION
Device
LM2574DW–ADJ
LM2574N–XX
TA = –40° to +125°C
Operating
Temperature Range
Package
SO–16L
DIP–8
XX = Voltage Option, i.e, 3.3, 5, 12, 15 V; and ADJ for
Adjustable Output.
©
Motorola, Inc. 1999
Rev 2, 07/1999
ONSEMI [ ON SEMICONDUCTOR ]
