Dual 2-Phase, No RDC/DC Controller with Output Tracking

The LTC3737 is a 2-phase dual step-down switching regulator controller that requires few external components. The constant frequency current mode architecture provides excellent AC and DC load and line regulation. MOSFET VDS sensing eliminates the need for current sense resistors and improves efficiency. Power loss and noise due to the ESR of the input capacitance are minimized by operating the two controllers out of phase.

Burst Mode operation provides high efficiency operation at light loads. 100% duty cycle provides low dropout operation and extends battery operating time.

Switching frequency can be programmed up to 750kHz, allowing the use of small surface mount inductors and capacitors. For noise sensitive applications, the LTC3737 can be externally synchronized from 250kHz to 850kHz.

Other features include a power good output voltage monitor, a tracking input and internal soft-start.

The LTC3737 is available in the low profile thermally enhanced (4mm × 4mm) QFN package or a 24-lead SSOP narrow package.

Protected by U.S. Patents, including 5481178, 5731694, 5929620, 6144194, 6580258, 5994885

Applications

* One or Two Lithium-Ion Powered Devices

* Notebook and Palmtop Computers, PDAs

* Portable Instruments

* Distributed DC Power Systems

* Sense Resistor Optional

* Out-of-Phase Controllers Reduce Required Input Capacitance

* Programmable Output Voltage Tracking

* Constant Frequency Current Mode Architecture

* Wide VIN Range: 2.75V to 9.8V

* Wide VOUT Range: 0.6V to VIN

* 0.6V ±1.5% Reference

* Low Dropout Operation: 100% Duty Cycle

* True PLL for Frequency Locking or Adjustment (Frequency Range 250kHz to 850kHz)

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

* Internal Soft-Start Circuitry

* Selectable Maximum Peak Current Sense Threshold

* Power Good Output Voltage Monitor

* Output Overvoltage Protection

* Micropower Shutdown: IQ = 9µA

* Tiny 4mm × 4mm QFN and 24-Lead SSOP Packages