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Three Phase Step-Down DC/DC Controller Targets High Current Rails

May 13 2010 - MILPITAS, CA
  • Linear Technology Corporation introduces the LTC3829, a three-phase single output high efficiency (up to 95%) 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). The differential amplifier provides true remote output voltage sensing of both the positive and negative terminals, enabling high accuracy regulation independent of IR losses in trace runs, vias and interconnects. Applications include high current ASIC and FPGA supplies, power distribution buses, high power audio amplifiers and network servers.


    The LTC3829 operates with all N-channel MOSFETs from input voltages ranging from 4.5V to 38V, and it can 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 accurate and constant current limit set point over a broad temperature range. The powerful on-board gate drivers minimize MOSFET switching losses and allows the use of multiple MOSFETs connected in parallel. A fixed operating frequency can be programmed from 250kHz to 770kHz or can be synchronized to an external clock with its internal PLL. The device's minimum on time of just 90ns makes the LTC3829 ideal for high step-down ratio applications.


    The LTC3829 incorporates an adjustable Stage Shedding technique to increase light load efficiency by eliminating the gate charge and switching losses of two of its output stages. In addition, the LTC3829 can be configured for adjustable Burst Mode® operation, producing even higher efficiency at light loads. An optional non-linear control mode improves load step transient response and adaptive voltage positioning (AVP) minimizes the maximum transient voltage deviation during a step-load.


    Tracking and sequencing functions allow the optimization of power-up and power-down of multiple power supplies. Additional features include current mode control, an on-board LDO for IC power, programmable soft start, a power good output and external VCC.


    The LTC3829 is available in thermally enhanced 38-lead TSSOP or 38-lead 5mm × 7mm QFN packages and operates over a –40ºC to 125ºC operating junction temperature range with the 1000-piece price starting at $3.71 each. Both versions are available from stock. For more information, visit www.linear.com.


    Summary Features LTC3829


    • High Power – Up to 150A IOUT
    • PolyPhase® Operation – Up to 6 Phases
    • High Efficiency – Up to 95%
    • Wide VIN Range from 4.5V to 38V
    • VOUT Ranging from 0.6V to 5V, ±0.75% Accuracy
    • RSENSE or DCR Current Sensing
    • Programmable DCR Temperature Compensation
    • Powerful On-Board N-Channel MOSFET Gate Driver
    • Adjustable Stage Shedding
    • Programmable Burst Mode® Operation
    • Optional Non-Linear Control Mode
    • Adaptive Voltage Positioning
    • True Differential Amplifiers for Remote Output Voltage Sensing
    • Output Voltage Tracking or Programmable Soft-Start
    • Phase-Lockable Fixed Frequency from 250kHz to 770kHz
    • Current Mode Control for Accurate & Easy Current Sharing


    High Power Single Output PolyPhase DC/DC Controller

    LTC3829 PR Image

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