Features

• Wide Input Range: 4V to 36V
• One 2.7A and Two 1.8A Output Switching Regulators with Internal Power Switches
• Low Dropout Linear Regulator with External Transistor
• Antiphase Switching Reduces Ripple
• Independent Run, Tracking/Soft-Start, and Power Good Indicators Ease Supply Sequencing
• Uses Small Inductors and Ceramic Capacitors
• Adjustable, 250kHz to 2.5MHz Switching Frequency, Synchronizable Over the Full Range
• User Programmable Overvoltage and Undervoltage Lockouts
• Thermally Enhanced, 38-Lead TSSOP and 5mm × 7mm QFN Packages

Typical Application

Description

The LT®3507A is a triple, current mode, DC/DC converter with internal power switches and a low dropout regulator. The switching converters are step-down converters capable of generating one 2.7A output and two 1.8A outputs. All three converters are synchronized to a single oscillator. The 2.7A output runs with opposite phase to the other two converters, reducing input ripple current. Each regulator has independent shutdown and soft-start circuits, and generates a power good signal when its output is in regulation, easing power supply sequencing and interfacing with microcontrollers and DSPs.

The switching frequency is set with a single resistor yielding a range of 250kHz to 2.5MHz. The high switching frequency allows the use of small inductors and capacitors resulting in a very small triple output supply. The constant switching frequency, combined with low impedance ceramic capacitors, results in low, predictable output ripple. Frequency foldback and thermal shutdown provide protection against fault conditions. The LT3507A provides higher output current than available with the LT3507.