LTC3868

PRODUCTION

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 ≤ 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

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.


 LTC3868 LTC3868-1
Features Adjustable Current Limit, Clock Out Pin, Phase Modulation, Two PGOOD Fixed Current Limit, One PGOOD
Package QFN-32 SSOP-28

Applications

  • Notebook and Palmtop Computers
  • Portable Instruments
  • Battery Operated Digital Devices
  • Distributed DC Power Systems
LTC3868
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
Power System Management (PSM) & Sequencers 1
LTC2974
RECOMMENDED FOR NEW DESIGNS 4-Channel PMBus Power System Manager Featuring Accurate Output Current Measurement
Protection Switches & Controllers 2
LTC2955
RECOMMENDED FOR NEW DESIGNS Pushbutton On/Off Controller with Automatic Turn-On
LTC4365
RECOMMENDED FOR NEW DESIGNS Overvoltage, Undervoltage and Reverse Supply Protection Controller
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Tools & Simulations

LTspice

Models for the following parts are available in LTspice:

  • LTC3868
  • LTC3868-1

LTpowerCAD 1

Design tools for the following parts are available in LTpowerCAD:

  • LTC3868
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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