LTC3858-2

RECOMMENDED FOR NEW DESIGNS

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

Data Sheet Product Selection Table
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Overview

  • Low Operating IQ: 170μA (One Channel On)
  • Wide Output Voltage Range: 0.8V ≤ VOUT ≤ 24V
  • Wide VIN Range: 4V to 38V
  • 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-850kHz)
  • Programmable Fixed Frequency (50kHz-900kHz)
  • Selectable Continuous, Pulse-Skipping or Burst Mode® Operation at Light Loads
  • Very Low Dropout Operation: 99% Duty Cycle
  • Adjustable Output Voltage Soft-Start or Tracking
  • Power Good Output Voltage Monitor
  • Low Shutdown IQ: 8μA
  • Internal LDO Powers Gate Drive from VIN or EXTVCC
  • No Current Foldback During Start-Up
  • 5mm × 5mm QFN Package

The LTC3858-2 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 LTC3858-2 differs from the LTC3858 by having the overvoltage protection crowbar and short-circuit latchoff disabled. A wide 4V to 38V 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.

LTC3858 LTC3858-1 LTC3858-2
Features Adjustable Current Limit, Clock Output, Phase Modulation, 2 PGOOD Outputs Fixed Current Limit, One PGOOD Output Overvoltage protection crowbar and short-circuit latchoff disabled
Package QFN-32 SSOP-28 QFN-32

Applications

  • Automotive Systems
  • Battery Operated Digital Devices
  • Distributed DC Power Systems
LTC3858-2
Low IQ, Dual 2-Phase Synchronous Step-Down Controller
High Efficiency Dual 8.5V/3.3V Step-Down Converter Efficiency and Power Loss vs Load Current Product Package 1
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Documentation

Data Sheet 1

Reliability Data 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
Protection Switches & Controllers 2
LTC2955
RECOMMENDED FOR NEW DESIGNS Pushbutton On/Off Controller with Automatic Turn-On
LT4363
RECOMMENDED FOR NEW DESIGNS High Voltage Surge Stopper with Current Limit
Switching Regulators & Controllers 1
LTC3880
RECOMMENDED FOR NEW DESIGNS Dual Output PolyPhase Step-Down DC/DC Controller with Digital Power System Management
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Tools & Simulations

LTspice 1

Models for the following parts are available in LTspice:

  • LTC3858
  • LTC3858-1
  • LTC3858-2

LTpowerCAD 1

Design tools for the following parts are available in LTpowerCAD:

  • LTC3858
  • LTC3858-1
  • LTC3858-2
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.

LTpowerCAD

LTpowerCAD® is a power supply design program which selects power stage components, provides detailed power efficiency, shows quick loop Bode plot stability and load transient analysis, and can export to LTspice for simulation.

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