LT3686A - 37V/1.2A Step-Down Regulator in 3mm × 3mm DFN and MSE

Features

  • Wide Input Range:
    Operation from 3.6V to 37V

  • Overvoltage Lockout Protects Circuit Through 60V Transients
  • Low Minimum On-Time: Converts 16VIN to 3.3VOUT 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
  • IQ in Shutdown <1μA
  • Internally Compensated
  • Thermally Enhanced eMSOP and 3mm × 3mm DFN Packages
Designed for Automotive and Transportation Applications
AEC-Q100 generic family data available for specific packages


Typical Application

LT3686A Typical Application
LT3686A Typical Application

Description

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

Packaging

CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.

For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
Drawing
RoHS
LT3686AEDD#PBF 3x3 DFN-10 DD E 05-08-1699 Yes
LT3686AEDD#TRPBF 3x3 DFN-10 DD E 05-08-1699 Yes
LT3686AEMSE#PBF MS-12E MSE E 05-08-1666 Yes
LT3686AEMSE#TRPBF MS-12E MSE E 05-08-1666 Yes
LT3686AHMSE#PBF MS-12E MSE H 05-08-1666 Yes
LT3686AHMSE#TRPBF MS-12E MSE H 05-08-1666 Yes
LT3686AIDD#PBF 3x3 DFN-10 DD I 05-08-1699 Yes
LT3686AIDD#TRPBF 3x3 DFN-10 DD I 05-08-1699 Yes
LT3686AIMSE#PBF MS-12E MSE I 05-08-1666 Yes
LT3686AIMSE#TRPBF MS-12E MSE I 05-08-1666 Yes


LT3686A Package Drawing
LT3686A Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
(1-99)
Price
(1k)*
RoHS
LT3686AEDD#PBF 3x3 DFN-10 E $3.57 $2.50 Yes
LT3686AEDD#TRPBF 3x3 DFN-10 E $2.56 Yes
LT3686AEMSE#PBF MS-12E E $3.71 $2.60 Yes
LT3686AEMSE#TRPBF MS-12E E $2.66 Yes
LT3686AHMSE#PBF MS-12E H $4.49 $3.14 Yes
LT3686AHMSE#TRPBF MS-12E H $3.20 Yes
LT3686AIDD#PBF 3x3 DFN-10 I $3.97 $2.78 Yes
LT3686AIDD#TRPBF 3x3 DFN-10 I $2.84 Yes
LT3686AIMSE#PBF MS-12E I $4.13 $2.89 Yes
LT3686AIMSE#TRPBF MS-12E I $2.95 Yes
Buy NowRequest Samples
* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Part Number Description Price Documentation
DC1647A LT3686AEDD Demo Board | 5V ≤ VIN ≤ 37V (55V Transients), VOUT = 3.3V @ 1.2A, SYNC Pin $100.00
Buy Now
Click here to view our complete list of demo boards

Designed for Automotive and Transportation Applications

Please contact your local sales representative for more information regarding reliability reports and AEC-Q100 data or to inquire about parts that are not included. For more information, view our Automotive and Transportation page

Part Number Package Temp Price
(1-99)
Price
(1k)*
RoHS
LT3686AHMSE#PBF MS-12E H $4.49 $3.14 Yes
LT3686AHMSE#TRPBF MS-12E H $3.20 Yes
LT3686AIDD#PBF 3x3 DFN-10 I $3.97 $2.78 Yes
LT3686AIDD#TRPBF 3x3 DFN-10 I $2.84 Yes
LT3686AIMSE#PBF MS-12E I $4.13 $2.89 Yes
LT3686AIMSE#TRPBF MS-12E I $2.95 Yes
Buy NowRequest Samples
* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Applications

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

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Design Tools

LTspice

LTspice® software is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. Click here to download LTspice

To launch a ready to run LTspice demonstration circuit for this part:

  • Step 1: If you have not installed LTspice on this computer, download and install LTspice
  • Step 2: Once LTspice is installed, click on the link(s) below to launch the simulation
  • Step 3: If LTspice does not automatically open after clicking the link above, 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

To explore other ready to run LTspice demonstration circuits, please visit our Demo Circuits Collection.

Models for the following parts are available in LTspice:
LT3686
LT3686A

LTpowerCAD

The LTpowerCAD design tool is a complete power supply design tool program that can significantly ease the tasks of power supply design. It guides users to a solution, selects power stage components, provides detailed power efficiency, shows quick loop bode plot stability and load transient analysis, and can export a final design to LTspice for simulation. Click here to download LTpowerCAD

Design tools for the following parts are available in LTpowerCAD:
LT3686A

Technical Support