LT3845

NOT RECOMMENDED FOR NEW DESIGNS

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

Part Models: 8
1ku List Price: Starting From $4.19

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Part Details

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

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 V_IN.

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

Documentation

ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal. View our quality and reliability program and certifications for more information.

Part Model	Pin/Package Drawing	Documentation	CAD Symbols, Footprints, and 3D Models
LT3845EFE#PBF	16-Lead TSSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT3845EFE#TRPBF	16-Lead TSSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT3845EN#PBF	16-Lead PDIP (Narrow 0.30 Inch)	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT3845IFE#PBF	16-Lead TSSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT3845IFE#TRPBF	16-Lead TSSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT3845MPFE	16-Lead TSSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT3845MPFE#PBF	16-Lead TSSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT3845MPFE#TRPBF	16-Lead TSSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys

Part Models	Product Lifecycle	PCN

Apr 6, 2022 - 22_0068 Laser Top Mark for ETSSOP and TSSOP Packages Assembled in ADPG [PNG] and UTL
		PCN22_0068_Form Material_Report Delta Qualification Matrix
LT3845EFE#PBF	PRODUCTION
LT3845EFE#TRPBF	PRODUCTION
LT3845IFE#PBF	PRODUCTION
LT3845IFE#TRPBF	PRODUCTION
LT3845MPFE
LT3845MPFE#PBF	PRODUCTION
LT3845MPFE#TRPBF	PRODUCTION
Oct 11, 2022 - 22_0241 Epoxy Change from Henkel 8290 to 8290A for PDIP Package
		PCN22_0241_Form Material_Report Qualification Results Summary
LT3845EN#PBF	PRODUCTION
Aug 6, 2022 - 22_0172 Laser Top Mark Conversion for PDIP Packages Assembled in ADPG [PNG]
		PCN22_0172_Form Material_Report Delta Qualification Matrix
LT3845EN#PBF	PRODUCTION

This is the most up-to-date revision of the Data Sheet.

Hardware Ecosystem

Parts	Product Life Cycle	Description
Dual-Supply Monitors 1
LTC2960	RECOMMENDED FOR NEW DESIGNS	36V Nano-Current Two-Input Voltage Monitor
Multiple Output Buck Regulators 1
LTC3880	RECOMMENDED FOR NEW DESIGNS	Dual Output PolyPhase Step-Down DC/DC Controller with Digital Power System Management
Silicon Oscillators 1
LTC6909	PRODUCTION	1 to 8 Output, Multiphase Silicon Oscillator with Spread Spectrum Modulation
Surge Stopper, Overvoltage, and Overcurrent Protection 1
LT4363	RECOMMENDED FOR NEW DESIGNS	High Voltage Surge Stopper with Current Limit

Parts	Product Life Cycle	Description
LT3845A	RECOMMENDED FOR NEW DESIGNS	High Voltage Synchronous Current Mode Step-Down Controller with Adjustable Operating Frequency

Tools & Simulations

LTspice 2

Models for the following parts are available in LTspice:

LT3845
LT3845A

LTpowerCAD 1

LT3845 Project - DC1073A 20-55Vin to 12V/6.25A, 300kHz

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.

LTpowerCAD^® is a power supply design program which selects power stage components, provides detailed power efficiency, shows quick loop Bode plot stability and load transient analysis, and can export to LTspice for simulation.

Evaluation Kits

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

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Product Details

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.

Resources

DC1073A - Schematic
64.00K

DC1073A - Design File
773.00K

DC1073A - Demo Manual
270.00K

Latest Discussions

3 Years Ago

Part Details

Documentation

Data Sheet 1

Reliability Data 1

User Guide 1

Design Note 1

Controlled Drawings 1