Features

• 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

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.