LTC3851-1

PRODUCTION

Synchronous Step-Down Switching Regulator Controller

Data Sheet Product Selection Table
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Overview

  • Wide VIN Range: 4V to 38V Operation
  • RSENSE or DCR Current Sensing
  • ±1% Output Voltage Accuracy
  • Power Good Output Voltage Monitor
  • Phase-Lockable Fixed Frequency: 250kHz to 750kHz
  • Dual N-Channel MOSFET Synchronous Drive
  • Very Low Dropout Operation: 99% Duty Cycle
  • Adjustable Output Voltage Soft-Start or Tracking
  • Output Current Foldback Limiting
  • Output Overvoltage Protection
  • OPTI-LOOP® Compensation Minimizes COUT
  • Selectable Continuous, Pulse-Skipping or Burst Mode® Operation at Light Loads
  • Low Shutdown IQ: 20μA
  • VOUT Range: 0.8V to 5.5V
  • Thermally Enhanced 16-Lead MSOP or 3mm × 3mm QFN Package

The LTC3851-1 is a high performance synchronous step-down switching regulator controller that drives an all N-channel synchronous power MOSFET stage. A constant frequency current mode architecture allows a phase-lockable frequency of up to 750kHz.

OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The LTC3851-1 features a precision 0.8V reference and a power good indicator. A wide 4V to 38V (40V absolute maximum) input supply range encompasses most battery configurations and intermediate bus voltages.

The TK/SS pin ramps the output voltage during start-up and shutdown with coincident or ratiometric tracking. Current foldback limits MOSFET heat dissipation during short-circuit conditions. The MODE/PLLIN pin selects among Burst Mode operation, pulse skipping mode or continuous inductor current mode at light loads and allows the IC to be synchronized to an external clock.

 The LTC3851-1 is identical to the LTC3851 except that the ILIM pin is replaced by PGOOD.

Features
LTC3851 Not Recommended For New Designs
LTC3851-1 Not Recommended For New Designs
LTC3851A Adjustable Current Limit
LTC3851A-1 PGOOD Output

Applications

  • Automotive Systems
  • Telecom Systems
  • Industrial Equipment
  • Distributed DC Power Systems
LTC3851-1
Synchronous Step-Down Switching Regulator Controller
High Efficiency Synchronous Step-Down Converter Efficiency and Power Loss vs Load Current Product Package 1 Product Package 2
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Documentation

Data Sheet 1

Reliability Data 1

Application Note 1

Data Sheet

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Software Resources

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Hardware Ecosystem

Parts Product Life Cycle Description
Circuit Monitors 1
LTC2960
RECOMMENDED FOR NEW DESIGNS 36V Nano-Current Two-Input Voltage Monitor
Oscillators 1
LTC6909
PRODUCTION 1 to 8 Output, Multiphase Silicon Oscillator with Spread Spectrum Modulation
Protection Switches & Controllers 1
LT4363
RECOMMENDED FOR NEW DESIGNS High Voltage Surge Stopper with Current Limit
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Tools & Simulations

LTspice

Models for the following parts are available in LTspice:

  • LTC3851
  • LTC3851-1
  • LTC3851A
  • LTC3851A-1

LTpowerCAD

Design tools for the following parts are available in LTpowerCAD:

  • LTC3851A
  • LTC3851A-1
LTspice

LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.

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