DC/DC Converter delivers up to 1.2 A at 95% efficiency.

Press Release Summary:




Synchronous, fixed-frequency, buck-boost Model LTC3443 optimizes battery run-time for single-cell Li-Ion, multi-cell alkaline, or NiMH battery-powered applications. It operates from input voltage of 2.4-5.5V and can provide up to 1.2 A of output current at fixed output voltage between 2.4-5.25V. Operating frequency is set internally to 600 kHz and can be synchronized up to 1.2 MHz. Burst Mode® operation allows internal MOSFETs to operate intermittently based on load demand.



Original Press Release:



95% Efficient Buck-Boost Converter Delivers up to 1.2A



MILPITAS, CA - June 7, 2004 - Linear Technology Corporation announces the LTC3443, a true buck-boost DC/DC converter that can deliver up to 1.2 amps of output current at efficiencies as high as 95%. The LTC3443 is a synchronous, fixed frequency, buck-boost DC/DC converter designed to optimize battery run time for single cell Li-Ion, multi-cell alkaline or NiMH battery powered applications. It operates from an input voltage range of 2.4V to 5.5V and can provide up to 1.2A of output current at a fixed output voltage between 2.4V to 5.25V.

The LTC3443 utilizes a 600kHz switching frequency to provide high efficiencies at light load currents (500mA and below). The LTC3443 utilizes a unique Buck-Boost topology allowing it to operate above, below and equal to the output voltage with a single inductor, providing a continuous transfer function through all the operating modes, as the battery voltage declines. The operating frequency is set internally to 600kHz and can be synchronized up to 1.2MHz, allowing the use of tiny surface mount components and maintaining the switching noise well above the pass-band of most communication systems. The small implementation footprint makes it ideal for space-constrained environments such as cellular phones, PDAs, wireless and DSL modems and digital cameras.

The LTC3443 uses two 0.10 Ohm N-channel and two 0.11 Ohm P-channel switches in a constant frequency, synchronous switching topology to obtain efficiencies as high as 95%. The LTC3443's selectable Burst Mode® operation allows the internal power MOSFETs to operate intermittently based on load demand and reduces the quiescent current to a low 28uA when there is no load. It offers output disconnect in shutdown reducing ISD to less than 1uA while improving system reliability. Furthermore, the selectable Burst Mode operation is inhibited during synchronization or when the SYNC/MODE pin is pulled low, preventing low frequency ripple from interfering with audio circuitry. The LTC3443 also features anti-ringing control to minimize EMI, soft-start control, and thermal shutdown. The combination of the tiny solution footprint and Buck-Boost topology make the LTC3443 ideal for handheld applications, which require both optimum battery run-time and small size.

The LTC3443 is available from stock in a 4x3mm DFN package. Pricing starts at $3.25 each in 1,000-piece quantities.

Summary of Features: LTC3443
Fixed Frequency Operation with Input Voltages Above, Below or Equal to the Output
Up to 1.2A Continuous Output Current
Single Inductor, No Schottky Diodes Required
Only 28uA Quiescent Current In Burst Mode Operation
Output Disconnect in Shutdown: ISD<1uA
2.4V to 5.5V Input Voltage Range
2.4V to 5.25 Output Voltage Range
600kHz Constant Switching Frequency
Selectable Burst Mode Operation/Pulse Skipping Mode
4x3mm DFN-12 Package

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.

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