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LTC3857

Linear Technology
Part Number LTC3857
Manufacturer Linear Technology
Description Synchronous Step-Down Controller
Published Mar 19, 2010
Detailed Description FEATURES n Low Operating IQ: 50μA (One Channel On) n Wide Output Voltage Range: 0.8V ≤ VOUT ≤ 24V n Wide VIN Range: 4V t...
Datasheet PDF File LTC3857 PDF File

LTC3857
LTC3857

Overview
FEATURES n Low Operating IQ: 50μA (One Channel On) n Wide Output Voltage Range: 0.
8V ≤ VOUT ≤ 24V n Wide VIN Range: 4V to 38V (40V Abs Max) n RSENSE or DCR Current Sensing n Out-of-Phase Controllers Reduce Required Input Capacitance and Power Supply Induced Noise n OPTI-LOOP® Compensation Minimizes COUT n Phase-Lockable Frequency (75kHz-850kHz) n Programmable Fixed Frequency (50kHz-900kHz) n Selectable Continuous, Pulse-Skipping or Low Ripple Burst Mode® Operation at Light Loads n Selectable Current Limit n Very Low Dropout Operation: 99% Duty Cycle n Adjustable Output Voltage Soft-Start or Tracking n Power Good Output Voltage Monitors n Output Overvoltage Protection n Low Shutdown IQ : <8μA n Internal LDO Powers Gate Drive from VIN or EXTVCC n No Current Foldback During Start-up n 5mm × 5mm QFN Package APPLICATIONS n Automotive Always-On Systems n Battery Operated Digital Devices n Distributed DC Power Systems LTC3857 Low IQ, Dual, 2-Phase Synchronous Step-Down DESCRIPTION Controller The LTC®3857 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 ESR of the input capacitor ESR are minimized by operating the two controller output stages out of phase.
The 50μA no-load quiescent current extends operating run time in battery-powered systems.
The LTC3857 features a precision 0.
8V reference and power good output indicators.
A wide 4V to 38V input supply range encompasses a wide range of intermediate bus voltages and battery chemistries.
Independent TRACK/SS pins for each controller ramp the output voltages during start-up.
Current foldback limits MOSFET heat dissipation during short-circuit conditions.
The PLLIN/MODE pin selects among Burst Mode operation, pulse-skipping mode, or continuous inductor current mode at light loads.
For a leaded 28-lead SSOP package wi...


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