Analog Devices LT3740 Product Info

• Wide V_IN Range: 2.2V to 22V
• Internal Boost Provides 6V Gate Drive For V_IN Down to 2.2V
• No Sensing Resistor Required
• Dual N-Channel MOSFET Synchronous Drive
• Valley Current Mode Control
• Optimized for High Step-Down Ratio
• Power Good Output Voltage Monitor
• 0.8V Reference
• Three Pin-Selected Current Limit Levels
• Constant Switching Frequency: 300kHz
• Programmable Soft-Start
• Output Voltage Tracking
• Available in 16-Pin 5mm × 3mm DFN

The LT3740 is a synchronous step-down switching regulator controller that drives N-channel power MOSFET stages. The controller uses valley current mode architecture to achieve very low duty cycles with excellent transient response without requiring a sense resistor.

The LT3740 includes an internal step-up converter to provide a bias 7.8V higher than the input voltage for the drive. This enables the part to work from an input voltage as low as 2.2V.

The XREF pin is an external reference input that allows the user to override the internal 0.8V feedback reference with any lower value, allowing full control of the output voltage during operation, output voltage tracking or soft-start.

The LT3740 has three current limit levels that can be chosen by connecting the RANGE pin to ground, open, and input respectively.

Applications

• Notebook and Palmtop Computers, PDA
• Portable Instruments
• Distributed Power Systems