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LTC3868 - Low IQ, Dual 2-Phase Synchronous Step-Down Controller

The LTC3868 is a high performance dual step-down switching regulator controller that drives all N-channel synchronous power MOSFET stages. A constant frequency current mode architecture allows a phase-lockable frequency of up to 850kHz. Power loss and noise due to the input capacitor ESR are minimized by operating the two controller outputs out of phase.

The 170μA no-load quiescent current extends operating life in battery-powered systems. OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The LTC3868 features a precision 0.8V reference and a power good output indicator. A wide 4V to 24V input supply range encompasses a wide range of intermediate bus voltages and battery chemistries.

Independent soft-start pins for each controller ramp the output voltages during start-up. Current foldback limits MOSFET heat dissipation during short-circuit conditions. The output short-circuit latchoff feature further protects the circuit in short-circuit conditions.

For a leaded 28-lead SSOP package with a fixed current limit and one PGOOD output, without phase modulation or a clock output, see the LTC3868-1 data sheet.

Features Low Operating IQ: 170μA (One Channel On) Wide Output Voltage Range: 0.8V ≤ VOUT ≤ 14V Wide VIN Range: 4V to 24V RSENSE or DCR Current Sensing Out-of-Phase Controllers Reduce Required Input Capacitance and Power Supply Induced Noise OPTI-LOOP® Compensation Minimizes COUT Phase-Lockable Frequency (75kHz to 850kHz) Programmable Fixed Frequency (50kHz to 900kHz) Selectable Continuous, Pulse-Skipping or Burst Mode® Operation at Light Loads Very Low Dropout Operation: 99% Duty Cycle Adjustable Output Voltage Soft-Start Power Good Output Voltage Monitor Output Overvoltage Protection Output Latchoff Protection During Short Circuit Low Shutdown IQ: 8μA Internal LDO Powers Gate Drive from VIN or EXTVCC No Current Foldback During Start-Up Small 5mm × 5mm QFN Package Typical Application

Applications Notebook and Palmtop Computers Portable Instruments Battery Operated Digital Devices Distributed DC Power Systems Packaging

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