Features

• Wide Input Range: 3.2V to 40V
• Four 1A Outputs
• 100% Duty Cycle Operation
• Resistor-Programmed Constant Frequency
• Short-Circuit Robust
• Wide SYNC Range: 350kHz to 2.2MHz
• Anti-Phase Switching Reduces Ripple
• 800mV FB Voltage
• Independent Run/Soft-Start Pins
• Shutdown with UVLO
• Internal Compensation
• Thermal Shutdown
• Tiny 28-Lead (4mm × 5mm) Thermally Enhanced QFN Package

Typical Application

Description

The LT®3504 consists of four 1A output current buck regulators. The LT3504 has a wide operating input range of 3.2V to 40V. An on-chip boost regulator allows each channel to operate up to 100% duty cycle and eliminates the need for four external charge pump circuits. The LT3504 is designed to minimize external component count and results in a simple and small application circuit.

The LT3504 operates robustly in fault conditions. Cycleby- cycle peak current limit and catch diode current limit sensing protect the part during overload conditions. Thermal shutdown protects the power switches at elevated temperatures. Soft-start helps keep the peak inductor current under control during startup.

The LT3504 also features output voltage tracking and sequencing, programmable frequency, programmable undervoltage lockout, and a power good pin to indicate when all outputs are in regulation.