Features

• Wide Input Range:
  Operation from 3.6V to 37V
  Overvoltage Lockout Protects Circuit Through 55V 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
• Tracking and Soft-Start
• Precision UVLO
• Short-Circuit Robust
• I_Q in Shutdown <1μA
• Internally Compensated
• 10-Lead 3mm × 3mm DFN Package

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.