LM2574-5.0BWM MICREL [Micrel Semiconductor], LM2574-5.0BWM Datasheet

LM2574-5.0BWM

Manufacturer Part Number

LM2574-5.0BWM

Description

52kHz Simple 0.5A Buck Regulator

Manufacturer

MICREL [Micrel Semiconductor]

Datasheet

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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

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

December 2003

LM2574

10% of the frequency.

Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com

UNREGULATED

40V MAX

DC IN

22µF

Figure 1. Fixed Output Regulator Circuit

PWR

GND

LM2574

GND

SIG

OFF

ON/

OUT

Features

• 3.3V, 5V, 12V, and adjustable output versions

• Adjustable version output 1.23V to 37V 4% max. over

• 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

LM2574BN

LM2574-3.3BN

LM2574-5.0BN

line and load conditions.

11DQ05

330µH

52kHz Simple 0.5A Buck Regulator

REGULATED

OUTPUT

0.5A

220µF

OUT

Junction Temp. Range

–40 C to +85 C

LM2574

8-pin Plastic DIP

Package

M9999-122303

Micrel

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LM2574-5.0BWM Summary of contents

Page 1

... LM2574 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 adjustable version with an output voltage range of 1 ...

Page 2

... LM2574 Pin Configuration M9999-122303 FB 1 SIG GND 2 ON/OFF 3 PWR GND 4 8-Pin DIP ( OUTPUT VIN December 2003 Micrel ...

Page 3

... All limits at temperature extremes are guaranteed via testing. 3. External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance. When the LM2574 is used as shown in Figure 1 test circuit, system performance will be shown in system parameters section of teristics.” ...

Page 4

... ON/OFF = 5V (OFF) ON/OFF = 0V (ON LM2574 330µH (adjustable) OUT PWR SIG ON/ GND GND OFF 11DQ06 Figure 2. Adjustable Regulator Test Circuit LM2574– C 330 OUT PWR SIG ON/ GND GND OFF 11DQ06 Figure 3. Fixed Regulator Test Circuit 4 Min Typ 50 47 ...

Page 5

... LM2574 Typical Characteristics (Circuit of Figure 1) Supply Current 20 Measured at Ground Pin 25˚ OUT = LOAD to 0. INPUT VOLTAGE (V) Current Limit 1 25V 1 0.5 0 -75 -50 - 100 125 150 JUNCTION TEMPERATURE (˚C) Minimum Operating Voltage 5 ...

Page 6

... LM2574 Typical Performance Characteristics (continued) Normalized Feedback Voltage -10 -15 -20 -25 -75 -50 - 100 125 150 * Adjustable version only M9999-122303 Feedback Voltage vs Duty Cycle 12V 15 I LOAD = 100mA Normalized 25˚ -10 -15 -20 0 JUNCTION TEMPERATURE (˚C) ...

Page 7

... LM2574 Block Diagrams INTERNAL REGULATOR FEED- 4 BACK FIXED GAIN ERROR AMP 3.1k COMPARATOR + 1. 1.23V BAND-GAP 52 kHz RESET REFERENCE OSCILLATOR Note: Pin numbers are for the TO-220 package Fixed Regulator December 2003 ON/OFF ON/OFF 1 FEED- 1/2 AMP 4 BACK SWITCH DRIVER 2 OUTPUT THERMAL ...

Page 8

... LM2574 Package Information 0.018 (0.57) MICREL, INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA + 1 (408) 944-0800 TEL The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. ...

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