Dual 2-Phase, No R, Synchronous Controller with Spread Spectrum

The LTC3736-1 is a 2-phase dual synchronous stepdown switching regulator controller with tracking that drives external complementary power MOSFETs using few external components. The constant frequency current mode architecture with MOSFET VDS sensing eliminates the need for 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.

A unique spread spectrum architecture randomly varies the LTC3736-1’s switching frequency from 450kHz to 580kHz, significantly reducing the peak radiated and conducted noise on both the input and output supplies, making it easier to comply with electromagnetic interference (EMI) standards.

Pulse skipping operation provides high efficiency at light loads. 100% duty cycle capability provides low dropout operation, extending operating time in battery-powered systems. The high switching frequencies allow for the use of small surface mount inductors and capacitors.

The LTC3736-1 is available in the low profile (0.75mm) 24-pin thermally enhanced (4mm × 4mm) QFN package and 24-lead narrow SSOP packages.

Max Current Sense Voltage

Burst Mode

Soft Start

Spread Spectrum

LTC3736

204mV

Yes

No

No

LTC3736-1

204mV

No

No

Yes

LTC3736-2

345mV

No

Yes

No

Applications

* One or Two Lithium-Ion Powered Devices

* Notebook and Palmtop Computers, PDAs

* Portable Instruments

* Distributed DC Power Systems

* Spread Spectrum Operation

* Tracking Function

* No Current Sense Resistors Required

* Out-of-Phase Controllers Reduce Required

* Input Capacitance

* Wide VIN Range: 2.75V to 9.8V

* Current Mode Operation

* 0.6V ±1.5% Voltage Reference