DC to DC Power Supplies (Converters)
Step-Up DC/DC Converter offers true output disconnect.
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Press Release Summary:
Model LTC3421 is a 3 MHz, current mode, synchronous boost DC/DC converter suited for Li-Ion and single/multi-cell alkaline/NiMH applications. Internal switches provide 3 A current limit and deliver output voltages up to 5.25 V from input voltage of 0.5-4.5 V. Converter delivers up to 1.5 A of continuous output current from 2 alkaline cells. Synchronous rectification enables efficiencies of 96% while Burst Mode® operation lowers quiescent current to 12 µA.
Original Press Release:
96% Efficient, 3A, 3MHz Synchronous Step-Up DC/DC Converter with Output Disconnect
MILPITAS, CA - January 14, 2004 - Linear Technology announces the LTC3421, a 3MHz, current mode, synchronous boost DC/DC converter with true output disconnect and inrush current limiting. Its internal switches provide a 3A current limit (min) and deliver output voltages as high as 5.25V from an input voltage range of 0.5V to 4.5V, making the device ideal for Li-Ion and single/multi-cell alkaline/NiMH applications. The LTC3421 delivers up to 1.5A of continuous output current from two alkaline cells. Synchronous rectification enables efficiencies of 96% while Burst Mode® operation lowers quiescent current to only 12uA, providing maximum battery run-time in handheld applications. The combination of a 4 x 4mm QFN package and a constant switching frequency of 3MHz minimizes both inductor and capacitor sizes, providing a tiny solution footprint ideal for handheld applications.
The LTC3421 uses internal switches with an RDS(ON) of only 0.10 Ù (N-Channel) and 0.14 Ù (P-Channel) to deliver efficiencies as high as 96%. Either automatic or manual Burst Mode operation can be enabled to reduce no load quiescent current to only 12uA. The average current level for enabling Automatic Burst Mode can be programmed by the user via a resistor/capacitor to optimize light load efficiency, while true output disconnect eliminates inrush current and allows zero load current in shutdown. In noise-sensitive applications, the BURST pin can be configured to provide forced continuous operation to reduce noise and potential RF interference. An open-drain uncommitted low-battery comparator is included and maintains operation in applications with a secondary cell powering the output voltage during shutdown. Additional features include adjustable current limit, anti-ring control, programmable soft-start, external synchronization capability, a reference output, and thermal protection. For boost applications, which require up to 2A of output current, and where a small solution size and low maximum battery run-time are defining factors, the LTC3421 delivers the best solution.
The LTC3421EUF is available from stock in a 24-lead QFN package. Pricing starts at $3.50 each for 1,000-piece quantities.
Summary of Features: LTC3421
VIN Range of 0.5V to 4.5V, VOUT up to 5.25V
96% Efficiency
Up to 1.5A Continuous Output Current from Two Alkaline Cells
Constant 3MHz Switching Frequency
True Output Disconnect and Inrush Current Limiting
Adjustable Auto Burst Mode Threshold
Low Supply Current: 12uA, <1uA in Shutdown
Low Battery Comparator
Thermally Enhanced 4 x 4mm QFN-24 Package
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.
