38VIN Dual Synchronous Step-Down DC/DC Controller with 1% Accurate Pin-Selectable Output Voltages

Feb 23 2010 - MILPITAS, CA
  • Linear Technology Corporation announces the LTC3865/-1, a 95% efficient, dual output synchronous step-down DC/DC controller with 2-pin selectable VOUT programming, a feature that saves 4 precision feedback resistors. The output voltages maintain a tight ±1% accuracy including initial set-point, a –40°C to 125°C operating temperature range and load/line regulation. Nine selectable output voltages ranging from 0.6V to 5V are possible. The 4.5V to 38V input voltage range encompasses a wide variety of applications including most intermediate bus voltages and battery chemistries. The strong on-board N-channel MOSFET driver enables the use of high power external MOSFETs to produce output currents as high as 20A. Applications include point-of-load regulators in medical, industrial, automotive, datacom, telecom and multifunction printers.

    A constant-frequency current mode architecture allows a selectable fixed or phase-lockable (PLL) switching frequency from 250kHz to 770kHz. Power loss and supply noise are minimized by operating the stages 180° out-of-phase. OPTI-LOOP® compensation reduces the transient response and can be optimized over a wide range of output capacitance and ESR values, including all ceramic input and output capacitors. Output current sensing is accomplished by measuring the voltage drop across the output inductor (DCR) for maximum efficiency or by using an optional sense resistor. Current foldback limits MOSFET heat dissipation during short-circuit conditions. In addition, the LTC3865/-1 has adjustable soft-start or tracking to control the output voltage start-up characteristics. With capability up to 99% duty cycle, the LTC3865/-1 has a very low drop-out voltage, a useful feature for extending run times in battery powered applications.

    The LTC3865/-1 is offered in thermally enhanced 5mm × 5mm QFN-32 and SSOP-38 packages. Pricing for 1,000-piece quantities starts at $2.65 each. For more information, visit www.linear.com.

    Summary Features LTC3865/-1

    • Two Pin-Selectable (9 Settings) Output Voltage Programming from 0.6V to 5.0V
    • Save 4 precision Feedback Resistors
    • Synchronous Rectification for up to 95% Efficiency
    • Wide 4.5V to 38V Input Voltage Range
    • ±1% Total DC Output Voltage Accuracy over –40°C to +125°C
    • Dual, 180° Out-of-Phase Controllers Reduce Noise & Input Capacitance
    • DCR or RSENSE Current Sense Options
    • Strong On-Board N-Channel MOSFET Driver
    • Phase Lockable Fixed Operating Frequency from 250kHz to 770kHz
    • Programmable Soft-Start or Tracking
    • Adjustable Current Limit
    • Current Mode Control
    • Power Good Signals

    Dual Synchronous Step-Down DC/DC Controller


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