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Synchronous Boost Regulator Offers
Output Disconnect & Soft-Start

Linear Technology Corporation Press Release - 9/24/2007

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200mA of continuous output current from a single or 400mA from dual alkaline cells.

Efficiency and Power Loss from the LTC3528/b step-up DC/DC converters

Efficiency and Power Loss
from the LTC3528/b step-up DC/DC converters

MILPITAS, Ca. - Linear Technology Corporation announces the LTC3528/B, 1MHz, current mode, synchronous boost DC/DC converters with output disconnect and integrated soft-start capability. Their internal 1A switches can deliver output voltages as high as 5.25V from an input voltage range of 0.70V (start-up, 0.5V when running) to 5V, making them ideal for Li-Ion/Polymer or single/multicell alkaline/NiMH applications.

The LTC3528/B can deliver up to 200mA of continuous output current (at 3.3V) from a single alkaline cell or 400mA from dual alkaline cells. Synchronous rectification enables efficiencies of up to 94% while Burst ModeŽ operation lowers quiescent current to only 12uA(LTC3528), providing extended battery run-time in handheld applications. The combination of a 2mm x 3mm DFN-8 package and a constant switching frequency of 1MHz minimize both inductor and capacitor sizes, providing a tiny solution footprint required in handheld applications.

The LTC3528/B has internal switches with an RDS(ON) of only 0.175 Ohm (N-Channel) and 0.25 Ohm (P-Channel) to deliver efficiencies as high as 94%. The output disconnect feature allows the output to be completely discharged in shutdown. It also limits the inrush of current during start-up, minimizing surge currents seen by the input supply.

The LTC3528/B will also regulate the output when the input voltage exceeds the output voltage. Additional features include anti-ringing control, short-circuit protection, soft-start, and thermal protection. The LTC3528/B delivers an ideal solution for boost applications requiring up to 400mA of output current and where a small solution size and low maximum battery run-time are defining factors.

For applications demanding the lowest possible noise operation, The LTC3528B version is available with the Burst Mode feature disabled. This version runs in continuous mode at all current levels, slightly reducing light load efficiency. However, it minimizes possible interference of switching noise with onboard noise suppression circuitry.

LTC3528EDDB and LTC3528BEDDB are both available from stock in 8-lead DFN packages. 1,000-piece pricing starts at $1.95 each.

Summary of Features: LTC3528/B

  • Delivers 3.3V at 200mA from a Single Alkaline/NiMH Cell or 3.3V at 400mA from Two Cells
  • VIN Start-Up Voltage: 700mV
  • 1.6V to 5.25V VOUT Range
  • Up to 94% Efficiency
  • Output Disconnect
  • 1MHz Fixed Frequency Operation
  • VIN > VOUT Operation
  • Integrated Soft-Start
  • Current Mode Control with Internal Compensation
  • Burst Mode Operation with 12uA Quiescent Current (LTC3528)
  • Low Noise PWM Operation (LTC3528B)
  • Internal Synchronous Rectifier
  • Logic Controlled Shutdown: <1µA
  • Anti-Ringing Control
  • Low Profile (2mm × 3mm × 0.75mm) DFN Package

For more information, visit the company's website at:

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