DC/DC Regulator offers up/down output voltage tracking.

Press Release Summary:



Housed in 5 x 5 x 0.75 mm QFN package, LTC3708 dual output, 2-phase, step-down DC/DC controller drives external N-channel MOSFETs synchronously to allow efficiencies to 96% while delivering 5 A at 2.5 V from 5 V input supply. Multiple units can be interfaced to track 4, 6, or 8 output voltages. It utilizes no-clock-latency operation, has 0.6 V ±1 V voltage reference, and offers external frequency synchronization, monotonic soft-start, and adjustable current limit.



Original Press Release:



Dual 2-Phase DC/DC Regulator Has Fast Transient Response & Up/Down Output Tracking



MILPITAS, CA - January 7, 2004 - Linear Technology Corporation introduces the LTC3708, a dual output 2-phase step-down DC/DC controller. The LTC3708 improves efficiency by eliminating the need for sense resistors, reduces cost by minimizing input and output capacitor requirements and ensures proper start up and shutdown of multi-voltage digital systems with its integrated voltage tracking function. Multiple LTC3708s can be interfaced together to track four, six or eight output voltages, eliminating the reliance on digital control, programming or glue-logic circuits that are often inaccurate and unreliable. The unique no-clock-latency operation of the LTC3708 is responsible for very fast load transient response, use of minimum output capacitors and reduction of solution cost and board space. The LTC3708 satisfies the stringent power up and power down sequencing requirements found in multiple supply rail systems in which FPGAs, CPLDs, graphic processors, A/D or D/A data converters and CPUs co-exist, each with specific startup and shutdown order.

The LTC3708 drives external N-channel MOSFETs synchronously to allow efficiencies as high as 96% while delivering 5A at 2.5V from a 5V input supply. The efficiency is maintained between 90% and 95% for 100mA to 15A output loads. The optional use of a sense resistor allows the user to either increase efficiency by sensing the voltage drop across RDS(ON) of the MOSFET or improve current limit accuracy by adding a sense resistor to the circuit. The IC operates from input supplies ranging from 5V to 36V. Adjustable output voltages provide regulation from 0.6V to a voltage very close to the input supply, each capable of delivering up to 20A. Two-phase operation minimizes the requirement on the input capacitors. Output voltage tracking is versatile, allowing ratiometric and coincident setup among many other options.

The LTC3708 is offered in a low profile (0.75mm) 5mm by 5mm QFN package and is rated for operation from -40°C to 85°C. Pricing starts at $4.80 each in 1,000-piece quantities.

Summary of Features: LTC3708

No RSENSE(TM) Option for Maximum Efficiency

Very Fast Transient Response

Adjustable Output Voltage Up/Down Tracking

2-Phase Operation

0.6V ±1V Voltage Reference

External Frequency Synchronization

Monotonic Soft-Start

Adjustable Current Limit

Company Background

Linear Technology Corporation was founded in 1981 as a manufacturer of high performance linear integrated circuits. Linear Technology products include operational, instrumentation and audio amplifiers; voltage regulators, power management devices, DC-DC converters and voltage references; comparators; monolithic filters; communications interface circuits; one-chip data acquisition sub-systems; pulse-width modulators and sample-and-hold devices; and high frequency devices. Applications for Linear Technology's high performance circuits include wireless and broadband telecommunications infrastructure, cellular telephones, networking products and satellite systems, notebook and desk top computers, computer peripherals, video/multimedia, industrial and medical instrumentation, automotive electronics, factory automation, process control, military and space systems, and high-end consumer products including digital cameras, MP3 players and other electronic products.

Note: LT, AND LTC are registered trademarks of Linear Technology Corp.

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