LT3640

PRODUCTION

Dual Monolithic Buck Regulator with Power-On Reset and Watchdog Timer

Data Sheet Product Selection Table

Part Models: 8
1ku List Price: Starting From $4.82

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Overview

High Voltage Buck Regulator:
- 4V to 35V Operating Range
- 1.3A Output Current
OVLO Protects Input to 55V
Low Voltage Synchronous Buck Regulator:
- 2.5V to 5.5V Input Voltage Range
- 1.1A Output Current
Synchronizable, Adjustable 350kHz to 2.5MHz Switching Frequency
Programmable Power-On Reset Timer
Programmable Window Mode Watchdog Timer
Typical Quiescent Current: 290μA
Short-Circuit Robust
Programmable Soft-Start
Low Shutdown Current: I_Q < 1μA
Available in Thermally Enhanced 28-Lead (4mm × 5mm) QFN and 28-Lead TSSOP Packages

Part Models: 8
1ku List Price: Starting From $4.82

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
LT3640EFE#PBF	28-Lead TSSOP w/ EP	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT3640EFE#TRPBF	28-Lead TSSOP w/ EP	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT3640EUFD#PBF	28-Lead QFN (4mm x 5mm x 0.75mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT3640EUFD#TRPBF	28-Lead QFN (4mm x 5mm x 0.75mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT3640IFE#PBF	28-Lead TSSOP w/ EP	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT3640IFE#TRPBF	28-Lead TSSOP w/ EP	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT3640IUFD#PBF	28-Lead QFN (4mm x 5mm x 0.75mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT3640IUFD#TRPBF	28-Lead QFN (4mm x 5mm x 0.75mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys

Part Models	Product Lifecycle	PCN

May 18, 2026 - 26_0072 Epoxy Change for Select TSSOP Products
		PCN26_0072_Form Material_Report Delta Qualification Matrix Qualification Results Summary
LT3640EFE#PBF	PRODUCTION
LT3640EFE#TRPBF	PRODUCTION
LT3640IFE#PBF	PRODUCTION
LT3640IFE#TRPBF	PRODUCTION
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
LT3640EFE#PBF	PRODUCTION
LT3640EFE#TRPBF	PRODUCTION
LT3640IFE#PBF	PRODUCTION
LT3640IFE#TRPBF	PRODUCTION
Jan 20, 2022 - 21_0269 Addition of Alternate Assembly Site ASE Taiwan for Select LFCSP Products
		PCN21_0269_Form Material_Report Detailed Change Description Qualification Results Summary
LT3640IUFD#PBF	PRODUCTION
LT3640IUFD#TRPBF	PRODUCTION

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

Software Resources

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Hardware Ecosystem

Parts	Product Life Cycle	Description
Circuit Monitors 1
LTC2960	RECOMMENDED FOR NEW DESIGNS	36V Nano-Current Two-Input Voltage Monitor
Power System Management (PSM) & Sequencers 1
LTC2974	RECOMMENDED FOR NEW DESIGNS	4-Channel PMBus Power System Manager Featuring Accurate Output Current Measurement
Protection Switches & Controllers 1
LT4363	RECOMMENDED FOR NEW DESIGNS	High Voltage Surge Stopper with Current Limit
Switching Regulators & Controllers 1
LTC3880	RECOMMENDED FOR NEW DESIGNS	Dual Output PolyPhase Step-Down DC/DC Controller with Digital Power System Management

Tools & Simulations

LTspice 1

LT3640 Demo Circuit - Dual High Voltage Buck with POR and WDT (5-35V to 3.3V @ 0.8A & 1.2V @ 1A)

Models for the following parts are available in LTspice:

LT3640

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.

Evaluation Kits

LT3640EFE Demo Board | 5V ≤ VIN ≤ 35V(55V Transients), VOUT1 = 1.2V @ 1A, VOUT2 = 3.3V @ 0.8A

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Product Details

Demonstration circuit 1359 is a Dual Monolithic Buck Regulator with Power-On Reset and Watchdog Timer featuring the LT3640. The board operates from inputs ranging from 5V to to 35V and withstands transients up to 55V. The outputs are 3.3V @ 0.8A and 1.2V @ 1A.

Resources

DC1359A - Schematic
8/18/2010

DC1359A Design Files
8/18/2010

DC1359A - Demo Board Manual
8/18/2010

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