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  • The L4973 is a step down monolithic power switching regulator delivering 3.5A at fixed voltages of 3.3V or 5.1V and using a simple external divider output adjustable voltage up to 50V. Realized in BCD mixed technology, the device uses an internal power D-MOS transistor (with a typical RDS(on) of 0.15Ω) to obtain very high efficiency and very fast switching times. Switching frequency up to 300KHz are achievable (the maximum power dissipation of the packages must be observed).

    A wide input voltage range between 8V to 55V and output voltages regulated from 3.3V to 40V cover the majority of the today applications. Features of this new generation of DC-DC converter includes pulse by pulse current limit, hiccup mode for output short circuit protection, voltage feed forward regulation, soft start, input/output synchronization, protection against feedback loop disconnection, inhibit for zero current consumption and thermal shutdown. Packages available are in plastic dual in line, DIP- 18 (12+3+3) for standard assembly, and SO20 (12+4+4) for SMD assembly.

    Key Features

    • Inhibit for zero current consumption (100mA at VCC= 24V)
    • Input/output synchronization function
    • Thermal shutdown
    • Protection against feedback disconnection
    • Soft start function
    • Output over voltage protection
    • Internal current limiting (pulse by pulse and HICCUP mode)
    • Zero load current operation (min 1mA)
    • Up to 3.5A step down converter
    • 3.3V and 5.1V (±1%) fixed output, and adjustable outputs from: 0.5V to 50V (3.3 type)5.1V to 50V (5.1 type)
    • Operating input voltage from 8V to 55V
    • Voltage feed forward
    • Precise 5.1V (1.5%) reference voltage externally available
    • Frequency adjustable up to 300kHz

Circuit Diagram

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L4973D3.3 SO-20 Tube
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L4973D3.3-013TR SO-20 Tape And Reel
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L4973D5.1 SO-20 Tube
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L4973V5.1 PDIP 18 Tube
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L4973D3.3

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L4973D5.1-013TR

Package

SO-20

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Tape And Reel

Unit Price (US$)

1.861*

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DIGIKEY WORLDWIDE 876 1 Order Now
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1000

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2000

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1000

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2034

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23145

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Quantity

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L4973V3.3

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PDIP 18

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768

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Quantity

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L4973D3.3-013TR

Package

SO-20

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Tape And Reel

Unit Price (US$)

1.811*

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DIGIKEY WORLDWIDE 986 1 Order Now
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MOUSER WORLDWIDE 479 1 Order Now
RUTRONIK EUROPE 1000 1000 Order Now

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L4973D5.1

Package

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RS COMPONENTS EUROPE 69 1 Order Now
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MOUSER WORLDWIDE 2129 1 Order Now
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ANGLIA Live EUROPE 307 1 Order Now

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69

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637

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2129

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96

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Quantity

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L4973V5.1

Package

PDIP 18

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334

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523

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1

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355

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1600

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20

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Unit Price (US$)

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Quantity

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ECCN (US)

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Technical Documentation

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      DS0169
      3.5 A step down switching regulator
      18.2
      635.57 KB
      PDF
      DS0169

      3.5 A step down switching regulator

    • Description Version Size Action
      AN1126
      Current sharing of the L4973 in a multiphase application
      1.2
      191.75 KB
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      Designing with L4973, 3.5 A high efficiency DC-DC converter
      10.1
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      Current sharing of the L4973 in a multiphase application

      AN938

      Designing with L4973, 3.5 A high efficiency DC-DC converter

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      ST1S03 alternative topology: Using a buck in a negative buck-boost configuration
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Publications and Collaterals

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Part Number Marketing Status Package Grade RoHS Compliance Grade Material Declaration**
L4973D3.3
Active
SO-20 Industrial Ecopack2
L4973D3.3-013TR
Active
SO-20 Industrial Ecopack2
L4973D5.1
Active
SO-20 Industrial Ecopack2
L4973D5.1-013TR
Active
SO-20 Industrial Ecopack2
L4973V3.3
Active
PDIP 18 Industrial Ecopack1
L4973V5.1
Active
PDIP 18 Industrial Ecopack1

L4973D3.3

Package:

SO-20

Material Declaration**:

PDF XML

Marketing Status

Active

Package

SO-20

Grade

Industrial

RoHS Compliance Grade

Ecopack2

L4973D3.3-013TR

Package:

SO-20

Material Declaration**:

PDF XML

Marketing Status

Active

Package

SO-20

Grade

Industrial

RoHS Compliance Grade

Ecopack2

L4973D5.1

Package:

SO-20

Material Declaration**:

PDF XML

Marketing Status

Active

Package

SO-20

Grade

Industrial

RoHS Compliance Grade

Ecopack2

L4973D5.1-013TR

Package:

SO-20

Material Declaration**:

PDF XML

Marketing Status

Active

Package

SO-20

Grade

Industrial

RoHS Compliance Grade

Ecopack2

L4973V3.3

Package:

PDIP 18

Material Declaration**:

PDF XML

Marketing Status

Active

Package

PDIP 18

Grade

Industrial

RoHS Compliance Grade

Ecopack1

L4973V5.1

Package:

PDIP 18

Material Declaration**:

PDF XML

Marketing Status

Active

Package

PDIP 18

Grade

Industrial

RoHS Compliance Grade

Ecopack1

(**) The Material Declaration forms available on st.com may be generic documents based on the most commonly used package within a package family. For this reason, they may not be 100% accurate for a specific device. Please contact our sales support for information on specific devices.

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