LTC3875 - Dual, 2-Phase, Synchronous Controller with Low Value DCR Sensing and Temperature Compensation

The LTC®3875 is a dual output current mode synchronous step-down DC/DC controller that drives all N-channel synchronous power MOSFET stages. It employs a unique architecture which enhances the signal-to-noise ratio of the current sense signal, allowing the use of very low DC resistance power inductors to maximize the efficiency in high current applications. This feature also reduces the switching jitter commonly found in low DCR applications.

The LTC3875 features two high speed remote sense differential amplifiers, programmable current sense limits from 10mV to 30mV and DCR temperature compensation to limit the maximum output current precisely over temperature.

A unique thermal balancing function adjusts per phase current in order to minimize the thermal stress for multichip single output applications. The LTC3875 also features a precise 0.6V reference with guaranteed accuracy of ±0.5% that provides an accurate output voltage from 0.6V to 3.5V. A 4.5V to 38V input voltage range allows it to support a wide variety of bus voltages. The LTC3875 is available in a low profile 40-lead 6mm × 6mm (0.5mm pitch) and 40-lead 5mm × 5mm (0.4mm pitch) QFN packages.

Features
  • Low Value DCR Current Sensing
  • Programmable DCR Temperature Compensation
  • ±0.5% 0.6V Output Voltage Accuracy
  • Dual True Remote Sensing Differential Amplifiers
  • Optional Fast Transient Operation
  • Phase-Lockable Fixed Frequency 250kHz to 720kHz
  • Dual, 180° Phased Controllers Reduce Required Input Capacitance and Power Supply Induced Noise
  • Dual N-Channel MOSFET Synchronous Drive
  • Wide VIN Range: 4.5V to 38V Operation
  • Output Voltage Range with Low DCR: 0.6V to 3.5V, without Low DCR: 0.6V to 5V
  • Adjustable Soft-Start Current Ramping or Tracking
  • Foldback Output Current Limiting
  • Clock Input and Output for Up to 12-Phase Operation
  • Short-Circuit Soft Recovery
  • Output Overvoltage Protection
  • Power Good Output Voltage Monitor
  • 40-Lead QFN Packages
Typical Application

Applications
  • Servers and Instruments
  • Telecom Systems
  • DC Power Distribution Systems
Packaging

Order Information
Part NumberPackageTempPrice(1-99)Price (1k)*
LTC3875EUH#PBF5x5 QFN-40E$4.96$3.47
LTC3875EUH#TRPBF5x5 QFN-40E$3.53
LTC3875EUJ#PBF6x6 QFN-40E$4.96$3.47
LTC3875EUJ#TRPBF6x6 QFN-40E$3.53
LTC3875IUH#PBF5x5 QFN-40I$5.22$3.65
LTC3875IUH#TRPBF5x5 QFN-40I$3.71
LTC3875IUJ#PBF6x6 QFN-40I$5.22$3.65
LTC3875IUJ#TRPBF6x6 QFN-40I$3.71
Demo Boards
Part NumberDescriptionPrice
DC2000ALTC3875EUJ Demo Board | 4.5V ≤ VIN ≤ 14V; VOUT1 = 1.0V @ 30A, VOUT2 = 1.5V @ 30AContact Factory
DC2055ALTC3875EUJ Demo Board | 4.5V ≤ VIN ≤ 14V; VOUT: 1V @ 120AContact Factory
DC2142ALTC3875EUJ/LTC3874IUFD Demo Board | 4.5V ≤ VIN ≤ 14V; VOUT: 1V @ 120AContact Factory
DC2225ALTC3875EUJ Demo Board | 4-Phase Sync Buck Solution, LTC3875 (x2), 4.5V ≤ VIN ≤ 14V; Vout = 1V @ 160AContact Factory
Datasheet
Reliability Data
LT Journal
Press Release
CAD Symbol CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprint compatible with Cadence ORCAD® v16.5 or later, Mentor Graphics PADS® v9.5 or later, and Altium 14.2.5 or later.
LTspice
LTpowerCAD
Related Product
LTC3875 - Dual, 2-Phase, Synchronous Controller with Low Value DCR Sensing and Temperature Compensation
LTC3875 Package Drawing LTC3875
R526 - Reliability Data
4-Phase Power Supply Delivers 120A in Tiny Footprint, Features Ultralow DCR Sensing for High Efficiency
High Efficiency PolyPhase Power Supply Delivers 30A per Phase with Ultralow Inductor DCR Sensing and Fast Transient Response
四相电源可在纤巧的占板面积内提供 120A,并具有旨在实现高效率的超低 DCR 检测功能
高效率多相电源采用超低电感器 DCR 检测方法
具 mΩ 以下 DCR 检测的多相、电流模式、同步降压型 DC/DC 控制器
LTC3875 Footprints and Symbols
LTC3874/LTC3875 Demo Circuit - High Efficiency, 4-Phase Step-Down Supply with Sub-Milliohm Inductor DCR Sensing (4.5-14V to 1V @ 120A)
LTC3875 Demo Circuit - High Efficiency Dual Output Step-Down Converter with Ultralow Inductor DCR Sensing and Fast Transient (4.5-14V to 1V @ 30A & 1.5V @ 30A)
LTC3875 Demo Circuit - Dual Phase 1.0V, 60A Power System with Ultralow Inductor DCR Sensing (4.5-14V to 1V @ 60A)
LTC3875 Demo Circuit - Four-Phase 1.0V, 120A Buck Converter with Ultralow Inductor DCR Sensing (4.5-14V to 1V @ 120A)
LTC3875 Project - Dual, Synchronous Controller with Sub mΩ Inductor DCR Current Sensing (4.5-14V to 1V @ 30A & 1.5V @ 30A)
LTC3875 Project - Poly-Phase, Synchronous Controllers with Sub mΩ Inductor DCR Sensing (4.5-14V to 1V @ 120A)