DC/DC Controller offers choice of operating modes.

Press Release Summary:




Model LTC3737 2-phase, 2-channel DC/DC step-down switching controller offers output tracking for proper startup of multiple voltage systems. Device features user-selectable mode to specify light load operation at high efficiency or low output ripple. For operation over max range of battery voltage or minimum input-output voltage differential, LTC3737 operates at up to 100% duty cycle regulating each output voltage from 0.6 V up to voltage equal to input supply.



Original Press Release:



Dual DC/DC Controller Tracks Outputs & Allows Choice of Highest Efficiency or Lowest Ripple at Light Loads



MILPITAS, CA - May 26, 2004 - Linear Technology Corporation introduces the LTC3737, a 2-phase two channel DC/DC step-down switching controller with output tracking to ensure proper startup of multiple voltage systems. The device also features a user selectable mode to specify light load operation at highest efficiency or lowest output ripple. For operation over the maximum range of a battery voltage (ex. 1- or 2-cell Li-Ion) or minimum input-output voltage differential (ex. 2.7VIN, 2.5VOUT), the LTC3737 can operate at up to 100% duty cycle regulating each output voltage from 0.6V up to a voltage equal to the input supply. Housed in a tiny 24-pin QFN package, this dual, 2-phase current mode controller saves board space and cost by using fewer input capacitors than dual single-phase DC/DC converters. Furthermore, with the LTC3737, designers have the option of designing with sense resistors for high accuracy current control or using MOSFET VDS sensing for higher efficiency. Applications include one or two Li-Ion powered devices, distributed power supplies, and systems with FPGAs or DSPs requiring power for core and I/O.

The LTC3737 drives an external P-channel MOSFET (per channel). Switching frequency is programmable up to 750kHz, allowing the use of small surface mount inductors and capacitors. Furthermore, the constant frequency current mode architecture provides excellent AC and DC load and line regulation. The LTC3737 features two modes: Burst Mode® operation for high efficiency and pulse skip operation for low ripple, selectable by asserting a voltage on the MODE pin. This allows the device to support applications emphasizing highest efficiency, as well as those demanding lowest "noise" (ripple) at light loads. For noise sensitive applications, the regulators can be externally synchronized from 300kHz to 750kHz. The part also includes integrated soft start and the Power Good output to indicate when the outputs have reached regulation.

The LTC3737 is rated for operation from -40°C to 85°C and is housed in a 24-pin 4mm x 4mm QFN package. 1,000-piece pricing starts at $3.65 each.

Summary of Features: LTC3737

Optional Sense Resistor: Senses Voltage Drop across Sense Resistor or VDS of MOSFET

Out-of-Phase Controllers Reduce Required Input Capacitance

Programmable Output Voltage Tracking

Constant Frequency, Current Mode Architecture

Input Voltage: 2.7V to 9.8V

True PLL for Frequency Locking

±1.5% 0.6V Reference

Power Good Output Indicator

Company Background

Linear Technology Corporation was founded in 1981 as a manufacturer of high performance linear integrated circuits. Linear Technology products include high performance amplifiers, comparators, voltage references, monolithic filters, linear regulators, DC-DC converters, battery chargers, data converters, communications interface circuits, RF signal conditioning circuits, and many other analog functions. Applications for Linear Technology's high performance circuits include telecommunications, cellular telephones, networking products such as optical switches, notebook and desktop computers, computer peripherals, video/multimedia, industrial instrumentation, security monitoring devices, high-end consumer products such as digital cameras and MP3 players, complex medical devices, automotive electronics, factory automation, process control, and military and space systems.

Note: LT, LTC, Burst Mode and are registered trademarks of Linear Technology Corp

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