Features

• Dual 100mV Rail-to-Rail Current Sense Amplifiers
• Wide Input Voltage Range: 2.5V to 25V
• 3A, 42V Internal Switch
• High Efficiency Power Conversion: Up to 93%
• Drives LEDs in Boost, Buck-Boost or Buck Mode
• Frequency Set by External Resistor: 200kHz to 3.5MHz
• Programmable Soft-Start
• Low V_CESAT Switch: 0.3V at 2.5A
• Capable of Positive and Negative Output Voltages (Boost, Inverting, SEPIC, Flyback)
• Available in Thermally Enhanced 20-Lead (4mm × 4mm) QFN and 20-Lead TSSOP Packages

Typical Application

Description

The LT®3477 is a current mode, 3A DC/DC step-up converter with dual rail-to-rail current sense amplifiers and an internal 3A, 42V switch. It combines a traditional voltage feedback loop and two unique current feedback loops to operate as a constant-current, constant-voltage source. Both current sense voltages are set at 100mV and can be adjusted independently using the I_ADJ1 and I_ADJ2 pins. Efficiency of up to 93% can be achieved in typical applications. The LT3477 features a programmable soft-start function to limit inductor current during start-up. Both inputs of the error amplifier are available externally allowing positive and negative output voltages (boost, inverting, SEPIC, Flyback). The switching frequency is programmable from 200kHz to 3.5MHz through an external resistor.

Available in thermally enhanced 20-pin (4mm × 4mm) QFN and 20-pin TSSOP packages, the LT3477 provides a complete solution for both constant-voltage and constantcurrent applications.