LTC3870-1 - PolyPhase Step-Down Slave Controller for Digital Power System Management


  • LTC3887-1 Phase Extender
  • Operates with Power Blocks, DrMOS or External Gate Drivers and MOSFETs
  • Cascade with Multiple Chips for Very Large Current Applications
  • Accurate PolyPhase Current Sharing
  • EXTVCC Capable of 5V to 14V Input
  • Wide VIN Range: 4.5V to 60V
  • Wide Output Voltage Range : 0.5V to 14V
  • Wide SYNC Frequency Range: 100kHz to 1MHz
  • Pin Programmable CCM/DCM Operation
  • Pin Programmable Phase-Shift Control
  • Available in a 24-Pin (4mm × 4mm) QFN Package

Typical Application

LTC3870-1 Typical Application
LTC3870-1 Typical Application


The LTC®3870-1 is a PolyPhase® step-down slave controller specially designed for multiphase operation with LTC's digital power system management DC/DC controllers. It provides a small and cost effective solution for supplying very large currents by cascading it with a LTC3887-1 controller. A peak current mode architecture provides the LTC3870-1 with excellent current sharing from phase to phase and from chip to chip.

Coherently working with the LTC3887-1, the LTC3870-1 does not require additional I2C addresses, and it supports all programmable features as well as fault protection. The constant switching frequency can be synchronized to an external clock from the LTC3887-1 over a range of 100kHz to 1MHz.

  Onboard MOSFET Gate Drivers Package
LTC3870 Yes 4x5 QFN-28
LTC3870-1 No – Works with DrMOS and Power Blocks 4x4 QFN-24


For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
LTC3870EUF-1#PBF 4x4 QFN-24 UF E 05-08-1697 Yes
LTC3870EUF-1#TRPBF 4x4 QFN-24 UF E 05-08-1697 Yes
LTC3870IUF-1#PBF 4x4 QFN-24 UF I 05-08-1697 Yes
LTC3870IUF-1#TRPBF 4x4 QFN-24 UF I 05-08-1697 Yes

LTC3870-1 Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
LTC3870EUF-1#PBF 4x4 QFN-24 E $3.36 $2.35 Yes
LTC3870EUF-1#TRPBF 4x4 QFN-24 E $2.41 Yes
LTC3870IUF-1#PBF 4x4 QFN-24 I $3.62 $2.53 Yes
LTC3870IUF-1#TRPBF 4x4 QFN-24 I $2.59 Yes
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* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Part Number Description Price Documentation
DC2454A LTC3887EUJ-1/LTC3870EUF-1 Demo Board | Dual Phase PMBus Buck Controller with Slave Controller, 7V ≤ VIN ≤ 14V, 0.8V ≤ VOUT ≤ 1.8V @ 100A Contact Factory
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  • High Power Distributed Power Systems
  • Telecom Systems
  • Industrial Applications

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