MIC4574_05 MICREL [Micrel Semiconductor], MIC4574_05 Datasheet

MIC4574_05

Manufacturer Part Number

MIC4574_05

Description

200kHz Simple 0.5A Buck Regulator

Manufacturer

MICREL [Micrel Semiconductor]

Datasheet

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General Description

The MIC4574 is a series of easy to use fixed and adjustable

BiCMOS step-down (buck) switch-mode voltage regulators.

The 200kHz MIC4574 duplicates the pinout and function of

the 52kHz LM2574. The higher switching frequency may

allow up to a 2:1 reduction in output filter inductor size.

The MIC4574 is available in 3.3V, and 5V fixed output

versions or a 1.23V to 20V adjustable output version. Both

versions are capable of driving a 0.5A load with excellent line

and load regulation.

The feedback voltage is guaranteed to ±2% tolerance for

adjustable versions, and the output voltage is guaranteed to

±3% for fixed versions, within specified voltages and load

conditions. The oscillator frequency is guaranteed to ±10%.

In shutdown mode, the regulator draws less than 200µA

standby current. The regulator performs cycle-by-cycle cur-

rent limiting and thermal shutdown for protection under fault

conditions.

This series of simple switch-mode regulators requires a

minimum number of external components and can operate

using a standard series of inductors. Frequency compensa-

tion is provided internally.

The MIC4574 is available in the DIP (N) package and is rated

over the industrial temperature range.

Data sheets and support documentation can be found on

Micrel’s web site at www.micrel.com.

Typical Application

June 2005

MIC4574

Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com

8V to 24V

Shutdown

Enable

47µF

35V

SHDN

MIC4574-5.0BN

SGND

Fixed Regulator

PGND

Features

• Fixed 200kHz operation

• 3.3V, 5V, and adjustable output versions

• Voltage over specified line and load conditions:

• Guaranteed 0.5A switch current

• Wide 4V to 24V input voltage range

• Wide 1.23V to 20V output voltage range

• Requires minimum external components

• < 200µA typical shutdown mode

• 75% efficiency (adjustable version > 75% typ.)

• Standard inductors and capacitors are

• Thermal shutdown

• Overcurrent protection

• 100% electrical thermal limit burn-in

Applications

• Simple high-efficiency step-down (buck) regulator

• Efficient preregulator for linear regulators

• On-card switching regulators

• Positive-to-negative converter (inverting buck-boost)

• Isolated flyback converter using minimum external

• Negative boost converter

25% of typical LM2574 values

components

Fixed version: ±3% max. output voltage

Adjustable version: ±2% max. feedback voltage

200kHz Simple 0.5A Buck Regulator

1N5819

100µH

5.0V/0.5A

220µF

16V

MIC4574

M9999-062105

Micrel, Inc.

Related parts for MIC4574_05

MIC4574_05 Summary of contents

Page 1

MIC4574 General Description The MIC4574 is a series of easy to use fixed and adjustable BiCMOS step-down (buck) switch-mode voltage regulators. The 200kHz MIC4574 duplicates the pinout and function of the 52kHz LM2574. The higher switching frequency may allow up ...

Page 2

MIC4574 Ordering Information Part Number Standard MIC4574-3.3BN MIC4574-5.0BN MIC4574BN Pin Configuration Pin Description Pin Number Pin Name SGND 3 SHDN 4 PGND 5 VIN M9999-062105 Temperature Pb-Free Voltage MIC4574-3.3YN 3.3V –40°C to ...

Page 3

MIC4574 Absolute Maximum Ratings Supply Voltage (V ), Note 5 ...................................... +40V IN Shutdown (V ) ....................................... –0.3V to +36V SHDN Output Switch (V ) steady state ................................. –1V SW Junction Temperature (T ) ...................................... +150°C J Storage Temperature ............................... ...

Page 4

MIC4574 Block Diagrams Shutdown Enable SHDN MIC4574-x.x Shutdown Enable SHDN MIC4574 M9999-062105 +24V max Internal Regulator Thermal Current Shutdown Limit 200kHz Oscillator Driver Com- parator 0.5A Switch 1.23V Bandgap Error Amp GND Block Diagram with External ...

Page 5

MIC4574 Functional Description The MIC4574 is a variable duty cycle switch-mode regulator with an internal power switch. Refer to the block diagrams. Supply Voltage The MIC4574 operates from a +4V to +24V unregulated input. Highest efficiency operation is from a ...

Page 6

MIC4574 Applications Information The applications circuits that follow have been constructed and tested. Refer to “Application Note 15” for additional information, including efficiency graphs and manufacturer’s addresses and telephone numbers for most circuits SHDN SW MIC4574-3.3BN 6V to ...

Page 7

MIC4574 Package Information 0.018 (0.57) MICREL INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA + 1 (408) 944-0800 TEL This information furnished by Micrel in this data sheet is believed to be accurate and reliable. However no responsibility is ...

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