LT3686 - 37V/1.2A Step-Down Regulator in 3mm × 3mm DFN

Features

  • Wide Input Range:
    Operation from 3.6V to 37V
    Overvoltage Lockout Protects Circuit Through 55V 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
  • Tracking and Soft-Start
  • Precision UVLO
  • Short-Circuit Robust
  • IQ in Shutdown <1μA
  • Internally Compensated
  • 10-Lead 3mm × 3mm DFN Package
Designed for Automotive and Transportation Applications
AEC-Q100 data available for specific packages


Typical Application

LT3686 Typical Application
LT3686 Typical Application

Description

The LT®3686 is a current mode PWM step-down DC/DC converter with an internal 1.2A power switch, packaged in 10-lead 3mm × 3mm DFN. The wide input range of 3.6V to 37V makes the LT3686 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 LT3686 particularly suitable for automotive applications.

Cycle-by-cycle current limit 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 LT3686 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.

  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
LT3686EDD#PBF 3x3 DFN-10 DD E 05-08-1699 Yes
LT3686EDD#TRPBF 3x3 DFN-10 DD E 05-08-1699 Yes
LT3686HDD#PBF 3x3 DFN-10 DD H 05-08-1699 Yes
LT3686HDD#TRPBF 3x3 DFN-10 DD H 05-08-1699 Yes
LT3686IDD#PBF 3x3 DFN-10 DD I 05-08-1699 Yes
LT3686IDD#TRPBF 3x3 DFN-10 DD I 05-08-1699 Yes


LT3686 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
LT3686EDD#PBF 3x3 DFN-10 E $3.57 $2.50 Yes
LT3686EDD#TRPBF 3x3 DFN-10 E $2.56 Yes
LT3686HDD#PBF 3x3 DFN-10 H $4.33 $3.03 Yes
LT3686HDD#TRPBF 3x3 DFN-10 H $3.09 Yes
LT3686IDD#PBF 3x3 DFN-10 I $3.97 $2.78 Yes
LT3686IDD#TRPBF 3x3 DFN-10 I $2.84 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
DC1323A LT3686EDD Demo Board | 5V ≤ VIN ≤ 37V(55V Transients), VOUT = 3.3V @ 1.2A $100.00
Buy Now
Click here to view our complete list of demo boards

Designed for Automotive and Transportation Applications

AEC-Q100 data is available for these specific part numbers. Please contact your local sales representative for more information regarding reliability reports 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
LT3686HDD#PBF 3x3 DFN-10 H $4.33 $3.03 Yes
LT3686HDD#TRPBF 3x3 DFN-10 H $3.09 Yes
LT3686IDD#PBF 3x3 DFN-10 I $3.97 $2.78 Yes
LT3686IDD#TRPBF 3x3 DFN-10 I $2.84 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

Product Notifications

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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