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Boost regulator offers output disconnect, integrated soft-start

Milpitas, Calif. — Linear Technology Corp. has introduced 1-MHz, current mode, synchronous boost DC/DC converters with an output disconnect and integrated soft-start capability. The combination of the LTC3528/B's 1-MHz constant switching frequency and 2 x 3-mm DFN-8 package make these devices suitable for handheld devices.

Their internal 1-A switches can deliver output voltages as high as 5.25 V from an input voltage range of 0.70 V (start-up, 0.5 V when running) to 5 V, making them a good fit for Li-ion/polymer or single/multi-cell alkaline/NiMH applications. The LTC3528/B can deliver up to 200 mA of continuous output current (at 3.3 V) from a single alkaline cell or 400 mA from dual alkaline cells.

Synchronous rectification enables efficiencies of up to 94% while burst mode operation lowers quiescent current to only 12 μA(LTC3528), providing extended battery run-time in handheld applications. 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.

The LTC3528 and LTC3528B devices provide internal switches with an RDS(ON) of 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, said Linear. They will also regulate the output when the input voltage exceeds the output voltage.

Other features include anti-ringing control, short-circuit protection, soft-start, and thermal protection.

Pricing: Starts at $1.95 each in quantities of 1,000.
Availability: The LTC3528EDDB and LTC3528BEDDB devices are both available from stock in 8-lead DFN packages.
Product information: LTC3528/B

Linear Technology , 1-408-432-1900, www.linear.com

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