Date: 14/05/2010

Three-phase synchronous step-down DC/DC controller from Linear Tech

Linear Technology has unveiled the LTC3829, a three-phase single output synchronous step-down DC/DC controller with PolyPhase operation, differential output voltage sensing and integrated phased-lock loop (PLL) clock synchronization. Up to six phases can be paralleled and clocked out of phase to minimize input and output filtering requirements for high current applications (up to 150A). Output voltage sensing is provided by the differential amplifier, thus enabling high accuracy regulation independent of IR losses in trace runs, vias and interconnects. It finds application in high current ASIC and FPGA supplies, power distribution buses, high power audio amplifiers and network servers.

The LTC3829 operates with all N-channel MOSFETs whose input voltages range from 4.5V to 38V. It is said to produce ± 0.75% accurate output voltages from 0.6V to 5V. The output current is sensed by monitoring the voltage drop across the output inductor (DCR) or by using a sense resistor. Programmable DCR temperature compensation maintains an constant current limit set point over a broad temperature range. The onboard gate drivers minimize switching losses of MOSFET, thus allowing use of multiple MOSFETs connected in parallel. The operating frequency can be programmed from 250kHz to 770kHz or can be synchronized to an external clock with its internal PLL. It is good for high step down ratio application due to it low on time of just 90ns. It also incorporates an adjustable Stage Shedding technique by eliminating the gate charge and switching losses of two of its output stages. It can also be configured for adjustable Burst Mode operation and also has an optional non-linear control mode, which maximum transient voltage deviation during a step-load. Its tracking and sequencing functions allow the optimization of power-up and power-down of multiple power supplies. Additional features include current mode control, an onboard LDO for IC power, programmable soft start, a power good output and external VCC.

Package: 38-lead TSSOP, 38-lead 5mm x 7mm QFN

Price: starting at US$3.71 1000-piece for 1000 pieces.