Features

• Seamless, Automatic Transition Between Two Input Power Sources
• Wide Input Voltage Range: 2.4V to 42V
• Wide Output Voltage Range: 0.818V to V_IN
• Up to 2.5A Continuous Output Current
• Pin Selectable Priority and Ideal Diode-OR Modes
• Burst Mode® Operation, I_Q = 2μA
• 95% Efficiency at 1A, V_IN = 12V, V_OUT = 5V
• 1μA Current in Shutdown
• Programmable Input UVLO Thresholds
• Input Valid, Priority Channel and PGOOD Indicators
• 200kHz to 2.2MHz Fixed Frequency PWM
• Synchronizable to an External Clock
• Current Mode Control with 60ns Minimum On-Time
• Minimal External Components
• Thermally Enhanced 28-Lead 4mm × 5mm QFN and 28-Lead TSSOP Packages

Typical Application

Description

The LTC®3126 is a high efficiency synchronous buck converter with an internal no-loss PowerPath™ supporting seamless operation from two separate input power sources. Pin selectable ideal diode-OR and priority input modes with user programmable undervoltage lockout thresholds provide full control over the transition between the input power sources. The fast, automatic switchover provided by the internal PowerPath eliminates the need for hold-up capacitors and minimizes disturbances on the output rail. An active input channel indicator and independent input and output power good signals provide complete feedback of the power system status.

A wide 2.4V to 42V input voltage range, 2.5A output current capability and 2μA Burst Mode operation quiescent current facilitate use of the LTC3126 with a wide variety of power sources including supercapacitors, automotive batteries, unregulated wall adapters and single to multi-cell stacks of most battery chemistries. Additional features include 1μA current in shutdown, internal softstart and thermal protection. The LTC3126 is available in thermally enhanced 28-lead 4mm × 5mm QFN and 28-lead TSSOP packages.