2-Phase, Low Input Voltage, Dual Step-Down DC/DC Controller

The LTC3701 is a 2-phase dual constant frequency current mode step-down DC/DC controller providing excellent load and line regulation. Power loss and noise due to ESR of the input capacitor are minimized by operating the two controller output stages out-of-phase.

The LTC3701 provides a 0.8V ±2% voltage reference and consumes only 460µA of quiescent current. To further maximize the life of a battery source, the external P-channel MOSFET is turned on continuously in dropout (100% duty cycle).

Switching frequency is internally set at 550kHz, allowing the use of small inductors and capacitors. For noise sensitive applications, the LTC3701 can be externally synchronized using its phase-locked loop. The frequency can also be externally set from 300kHz to 750kHz by applying a voltage to the PLLLPF pin. Burst Mode operation is inhibited during synchronization or when the EXTCLK/MODE pin is pulled low to reduce noise and RF interference.

The LTC3701 contains independent internal soft-start circuitry for each controller. Other features include a power good output voltage monitor and output overvoltage and short-circuit protection.

The LTC3701 is available in a small footprint 16-lead narrow SSOP package.

Applications

* One or Two Lithium-Ion Powered Applications

* Notebook and Handheld Computers

* Personal Digital Assistants

* Portable Instruments

* Distributed DC Power Systems

* Out-of-Phase Controllers Reduce Required Input Capacitance

* True PLL for Frequency Locking or Frequency Adjustment

* Operating Frequency Range: 300kHz to 750kHz

* Wide VIN Range: 2.5V to 10V

* Constant Frequency Current Mode Architecture

* Low Dropout: 100% Duty Cycle

* Power Good Output Voltage Monitor

* Internal Soft-Start Circuitry

* Selectable Burst Mode®/Pulse Skipping Operation at Light Loads

* Output Overvoltage Protection

* Low Quiescent Current: 460µA

* 0.8V ±2% Voltage Reference

* Small 16-Lead Narrow SSOP Package