Synchronous step-down DC-DC converter delivers 600 milliamps with spread-spectrum or PLL operation

Linear Technology Corp. in Milpitas, Calif., announces the LTC3543 high-efficiency, 2.25 MHz, synchronous buck regulator that can deliver as much as 600 milliamps of continuous output current from a 2-by-3-millimeter DFN package.

Jun 1st, 2007
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Linear Technology Corp. in Milpitas, Calif., announces the LTC3543 high-efficiency, 2.25 MHz, synchronous buck regulator that can deliver as much as 600 milliamps of continuous output current from a 2-by-3-millimeter DFN package. The LTC3543 can run in a constant 2.25 MHz frequency, spread spectrum or synchronized phase-lock-loop (PLL) mode, offering multiple choices for very-low-noise operation. Its current mode architecture operates from an input voltage range of 2.5 to 5.5 volts for single-cell Li-Ion, or multicell alkaline/NiCad/NiMH applications. It can generate output voltages as low as 0.6 volts, enabling it to power the latest generation of low voltage DSPs and microcontrollers. Its 2.25 MHz switching frequency enables the use of tiny, low-cost ceramic capacitors and inductors less than 1 millimeter high, providing a compact solution footprint for handheld applications. The LTC3543 uses internal switches with an RDS(ON) of only 0.35 Ohm (N-Channel) and 0.45 Ohm (P-Channel) to deliver efficiencies as high as 95 percent. It also utilizes low dropout 100 percent duty cycle operation to allow output voltages equal to VIN, further extending battery run-time. For maximum light load efficiency, the LTC3543 utilizes an automatic Low Ripple (< 20mVPK-PK) Burst Mode operation with only 45 microamps no-load quiescent current. If the application is noise sensitive, the burst-mode operation can be replaced with a lower-noise pulse-skipping, spread spectrum, or PLL (to an external clock between 1 MHz and 3 MHz) mode. In all modes, the device maintains shutdown currents of less than 1 microamps, maximizing battery run-time. Other features include ±2 percent output voltage accuracy, internal soft-start, and over-temperature protection. The LTC3543EDCB in available in a 2-by-3-millimeter DFN-6 package and is available from stock. For more information contact Linear Technology online at www.linear.com.

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