LT3845
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LT3845

High Voltage Synchronous Current Mode Step-Down Controller with Adjustable Operating Frequency

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warning : NOT RECOMMENDED FOR NEW DESIGNS tooltip
Part Details
Part Models 8
1ku List Price Starting From $4.19
Features
  • High Voltage Operation: Up to 60V
  • Synchronizable Up to 600kHz
  • Adjustable Constant Frequency: 100kHz to 500kHz
  • Output Voltages Up to 36V
  • Adaptive Nonoverlap Circuitry Prevents Switch Shoot-Through
  • Reverse Inductor Current Inhibit for Discontinuous Operation Improves Efficiency with Light Loads
  • Programmable Soft-Start
  • 120μA No Load Quiescent Current
  • 10μA Shutdown Supply Current
  • 1% Regulation Accuracy
  • Standard Gate N-Channel Power MOSFETs
  • Current Limit Unaffected by Duty Cycle
  • Reverse Overcurrent Protection
  • 16-Lead Thermally Enhanced TSSOP Package, 16-Pin PDIP
Additional Details
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The LT3845 is a high voltage, synchronous, current mode controller used for medium to high power, high efficiency supplies. It offers a wide 4V to 60V input range (7.5V minimum start-up voltage). An on-board regulator simplifies the biasing requirements by providing IC power directly from VIN.

Burst Mode® operation maintains high efficiency at light loads by reducing IC quiescent current to 120μA. Light load efficiency is also improved with the reverse inductor current inhibit function which supports discontinuous operation.

Additional features include adjustable fixed operating frequency that can be synchronized to an external clock for noise sensitive applications, gate drivers capable of driving large N-channel MOSFETs, a precision undervoltage lockout, 10μA shutdown current, short-circuit protection and a programmable soft-start.

The LT3845 is available in a 16-lead thermally enhanced TSSOP package and 16-pin through hole N package.

Features
LT3845 -
LT3845A Improved Performance In Over Current Conditions

Applications

  • 12V and 42V Automotive and Heavy Equipment
  • 48V Telecom Power Supplies
  • Avionics and Industrial Control Systems
  • Distributed Power Converters
Part Models 8
1ku List Price Starting From $4.19

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Documentation

Documentation

Part Model Pin/Package Drawing Documentation CAD Symbols, Footprints, and 3D Models
LT3845EFE#PBF
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LT3845MPFE
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Product Lifecycle

PCN

Apr 6, 2022

- 22_0068

Laser Top Mark for ETSSOP and TSSOP Packages Assembled in ADPG [PNG] and UTL

LT3845EFE#PBF

PRODUCTION

LT3845EFE#TRPBF

PRODUCTION

LT3845IFE#PBF

PRODUCTION

LT3845IFE#TRPBF

PRODUCTION

LT3845MPFE

PRODUCTION

LT3845MPFE#PBF

PRODUCTION

LT3845MPFE#TRPBF

PRODUCTION

Oct 11, 2022

- 22_0241

Epoxy Change from Henkel 8290 to 8290A for PDIP Package

Aug 6, 2022

- 22_0172

Laser Top Mark Conversion for PDIP Packages Assembled in ADPG [PNG]

Filter by Model

reset

Reset Filters

Part Models

Product Lifecycle

PCN

Apr 6, 2022

- 22_0068

arrow down

Laser Top Mark for ETSSOP and TSSOP Packages Assembled in ADPG [PNG] and UTL

LT3845EFE#PBF

PRODUCTION

LT3845EFE#TRPBF

PRODUCTION

LT3845IFE#PBF

PRODUCTION

LT3845IFE#TRPBF

PRODUCTION

LT3845MPFE

PRODUCTION

LT3845MPFE#PBF

PRODUCTION

LT3845MPFE#TRPBF

PRODUCTION

Oct 11, 2022

- 22_0241

arrow down

Epoxy Change from Henkel 8290 to 8290A for PDIP Package

Aug 6, 2022

- 22_0172

arrow down

Laser Top Mark Conversion for PDIP Packages Assembled in ADPG [PNG]

Software & Part Ecosystem

Software & Part Ecosystem

Evaluation Kit

Evaluation Kits 1

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DC1073A

LT3845EFE Demo Board | 20V < VIN < 55V, VOUT: 12V/6.25A

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DC1073A

LT3845EFE Demo Board | 20V < VIN < 55V, VOUT: 12V/6.25A

LT3845EFE Demo Board | 20V < VIN < 55V, VOUT: 12V/6.25A

Product Detail

Demonstration Circuit 1073 is a 100kHz-500kHz programmable frequency, high voltage, current-mode DC/DC step-down converter featuring the LT3845. The operating frequency can be synchronized up to 600kHz. The demo board is designed for 12V @ 6.25A (75W) output from a 20V to 55V input. A soft-start feature controls the output voltage slew rate at start-up, reducing current surges and voltage overshoots. The modes of operation (Burst Mode, Discontinuous Current Mode and Continuous Current Mode) are jumper selectable. Both Burst Mode and Discontinuous Current Mode increase the efficiency at light loads. Continuous Current Mode will maintain a constant switching frequency regardless of the load current.

Tools & Simulations

Tools & Simulations 2

LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.

To launch ready-to-run LTspice demonstration circuits for this part:

Step 1: Download and install LTspice on your computer.

Step 2: Click on the link in the section below to download a demonstration circuit.

Step 3: If LTspice does not automatically open after clicking the link below, you can instead run the simulation by right clicking on the link and selecting “Save Target As.” After saving the file to your computer, start LTspice and open the demonstration circuit by selecting ‘Open’ from the ‘File’ menu.

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