LT3686A

PRODUCTION

37V/1.2A Step-Down Regulator in 3mm × 3mm DFN and MSE

Part Models: 10
1ku List Price: Starting From $3.02

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Part Details

Wide Input Range:
- Operation from 3.6V to 37V
- Overvoltage Lockout Protects Circuit Through 60V Transients
Low Minimum On-Time:
- Converts 16V_IN to 3.3V_OUT at 2MHz
1.2A Output Current
Adjustable Frequency: 300kHz to 2.5MHz
Constant Switching Frequency at Light Loads

Can Be Synchronized to External Clock
Tracking and Soft-Start
Precision UVLO
Short-Circuit Robust
I_Q in Shutdown <1μA
Internally Compensated
Thermally Enhanced eMSOP and 3mm × 3mm DFN Packages

The LT3686A is a current mode PWM step-down DC/DC converter with an internal power switch. The wide input range of 3.6V to 37V makes the LT3686A suitable for regulating power from a wide variety of sources, including 24V industrial supplies and automotive batteries. Its high maximum frequency allows the use of tiny inductors and capacitors, resulting in a very small solution. Operating frequency above the AM band avoids interfering with radio reception, making the LT3686A particularly suitable for automotive applications.

Cycle-by-cycle current limit, thermal shutdown and DA current sense provide protection against fault conditions. Soft-start and frequency foldback eliminate input current surge during start-up. An optional internal regulated active load at the output via the BD pin keeps the LT3686A at full switching frequency at light loads, resulting in low, predictable output ripple above the audio and AM bands. Internal compensation and an internal boost diode reduce external component count.

The LT3686A offers external synchronization capability, whereas the LT3686 does not.


	Overvoltage Protections	Features
LT3686	55V	-
LT3686A	60V	External Synchronization

Applications

Automotive Systems
Battery-Powered Equipment
Wall Transformer Regulation
Distributed Supply Regulation

Part Models: 10
1ku List Price: Starting From $3.02

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
LT3686AEDD#PBF	10-Lead DFN (3mm x 3mm w/ EP)	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT3686AEDD#TRPBF	10-Lead DFN (3mm x 3mm w/ EP)	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT3686AEMSE#PBF	12-Lead MSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT3686AEMSE#TRPBF	12-Lead MSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT3686AHMSE#PBF	12-Lead MSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT3686AHMSE#TRPBF	12-Lead MSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT3686AIDD#PBF	10-Lead DFN (3mm x 3mm w/ EP)	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT3686AIDD#TRPBF	10-Lead DFN (3mm x 3mm w/ EP)	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT3686AIMSE#PBF	12-Lead MSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LT3686AIMSE#TRPBF	12-Lead MSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys

Part Models	Product Lifecycle	PCN

Feb 14, 2025 - 25_0016 Bond Wire Change from Gold to Copper Wire (Notification Only)
		PCN25_0016_Form Material_Report Qualification Results Summary
LT3686AEDD#PBF	PRODUCTION
LT3686AEDD#TRPBF	PRODUCTION
LT3686AEMSE#PBF	PRODUCTION
LT3686AEMSE#TRPBF	PRODUCTION
LT3686AHMSE#PBF	PRODUCTION
LT3686AHMSE#TRPBF	PRODUCTION
LT3686AIMSE#PBF	PRODUCTION
LT3686AIMSE#TRPBF	PRODUCTION
Oct 11, 2022 - 22_0244 Epoxy Change from Henkel 8290 to 8290A for MSOP Package
		PCN22_0244_Form Material_Report Qualification Results Summary Delta Qualification Matrix
LT3686AEMSE#PBF	PRODUCTION
LT3686AEMSE#TRPBF	PRODUCTION
LT3686AHMSE#PBF	PRODUCTION
LT3686AHMSE#TRPBF	PRODUCTION
LT3686AIMSE#PBF	PRODUCTION
LT3686AIMSE#TRPBF	PRODUCTION
Feb 4, 2020 - 20_0129 Laser Mark Conversion for 12-Lead MSOP Packages Assembled in ADPG and UTAC
		PCN20_0129_Form Material_Report
LT3686AEMSE#PBF	PRODUCTION
LT3686AEMSE#TRPBF	PRODUCTION
LT3686AHMSE#PBF	PRODUCTION
LT3686AHMSE#TRPBF	PRODUCTION
LT3686AIMSE#PBF	PRODUCTION
LT3686AIMSE#TRPBF	PRODUCTION
Apr 18, 2022 - 22_0050 UTAC Thai Limited (UTL) as Alternate Assembly Site for MSOP Packages / Devices
		PCN22_0050_Form Material_Report Qualification Results Summary Delta Qualification Matrix
LT3686AIMSE#PBF	PRODUCTION
LT3686AIMSE#TRPBF	PRODUCTION

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

Software Resources

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Hardware Ecosystem

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Digital Power System Managers 1
LTC2974	RECOMMENDED FOR NEW DESIGNS	4-Channel PMBus Power System Manager Featuring Accurate Output Current Measurement
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

Tools & Simulations

LTspice 1

LT3686A Demo Circuit - 37V Step-Down Regulator (12V to 3.3V@1.2A)

Models for the following parts are available in LTspice:

LT3686
LT3686A

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

LT3686AEDD Demo Board | 5V ≤ VIN ≤ 37V (55V Transients), VOUT = 3.3V @ 1.2A, SYNC Pin

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Product Details

Demo circuit 1647 is a current-mode PWM step-down DC/DC regulator with an internal power switch featuring the LT3686A. The LT3686A differs from the LT3686 in that it offers higher transient voltage protection and a SYNC pin. The demo circuit is designed for 3.3V/1.2A output from a 5V to 37V input with transients up to 55V. Its high 2.5MHz maximum frequency allows the use of tiny inductors and capacitors. Operating frequency above the AM band avoids interfering with radio reception, making the LT3686 particularly suitable for automotive applications. The LT3686A offers external synchronization capability, whereas the LT3686 does not.

Resources

DC1647A - Schematic
3/6/2012

DC1647A- Demo Manual
11/24/2010

DC1647A - Design Files
7/28/2011

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