Features and Benefits
- 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
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.
- Automotive Systems
- Battery-Powered Equipment
- Wall Transformer Regulation
- Distributed Supply Regulation
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (1)
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.
Tools & Simulations
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.
To launch ready-to-run LTspice demonstration circuits for this part:
Step 1: Download and install LTspice on your computer.
Step 2: Click on the link in the section below to download a demonstration circuit.
Step 3: If LTspice does not automatically open after clicking the link below, 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.
Models for the following parts are available in LTspice:
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.
Design tools for the following parts are available in LTpowerCAD:
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.
Sample & Buy
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 Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.