Power Management Switching Regulator Digitally Programmable Regulators

LTC2974 - 4-Channel PMBus Power System Manager Featuring Accurate Output Current Measurement

LTC1705 - Dual 550kHz Synchronous Switching Regulator Controller with 5-Bit VID and 150mA LDO

Features

  • Three Regulated Outputs: Core, I/O and CLK in One Package
  • Integrated Intel Mobile 5-Bit VID DAC
  • No External Current Sense Resistors
  • All N-Channel External MOSFET Architecture
  • 550kHz Switching Frequency Minimizes External Component Size and Cost
  • Integrated 150mA LDO Linear Regulator
  • Excellent DC Accuracy: 1.25% for Core, 2% for I/O and CLK Supplies
  • PGOOD Flag Monitors All Three Outputs
  • High Efficiency Over Wide Load Current Range
  • Low Shutdown Current: < 100µA
  • Switchers Run Out-of-Phase to Minimize CIN
  • Small 28-Pin Narrow SSOP Package

Typical Application

LTC1705 Typical Application

Description

The LTC1705 is a complete power supply controller for Intel Mobile Pentium processors. It includes two switching regulator controllers, each designed to drive a pair of N-channel MOSFETs in a voltage mode feedback, synchronous buck configuration, to provide the core and I/O supplies. The core controller includes a 5-bit DAC that conforms to the Intel Mobile VID specification. The IC also includes a low dropout linear regulator (LDO) that delivers up to 150mA of output current to provide the CLK supply. The LTC1705 uses a constant-frequency 550kHz PWM architecture, minimizing external component size and cost, as well as optimizing load transient performance. It provides better than 1.25% DC accuracy at its core output, and 2% at I/0 and CLK outputs. The high performance feedback loops allow the circuit to keep total output regulation within ±5% under all transient conditions. An open-drain PGOOD flag indicates that all three outputs are within ±10% of their regulated values. A shutdown circuit disables all three outputs if the RUN/SS pin is pulled to ground. In this mode, the LTC1705 supply current drops to below 100µA.

Packaging

CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.

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

Part Number Package Code Temp Package
Drawing		 RoHS
LTC1705EGN#PBF SSOP-28 GN E 05-08-1641 (GN28) Yes
LTC1705EGN#TRPBF SSOP-28 GN E 05-08-1641 (GN28) Yes


LTC1705 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
(1-99)		 Price
(1k)*		 RoHS
LTC1705EGN#PBF SSOP-28 E $6.00 $5.35 Yes
LTC1705EGN#TRPBF SSOP-28 E $5.36 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
DC295B LTC1705EGN | Intel Geyserville VRM, Vin = 4.5 - 5.5V, 0.925V - 2V @ 14Amp with 1.5V @ 2.5A and 2.5V @ 150mA Output (Requires DC296A for testing) Contact Factory
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Companion Boards

Part Number Description Price Documentation
DC296A LT1361CS8, LT1210CR | Mobile-CPU VRM Tester, 1 Input, 3 Output with 15A Load Pulser Contact Factory
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Click here to view our complete list of demo boards

Applications

  • Complete Power Supply Controller for Intel Mobile Pentium® Processors
  • Intel Mobile Pentium Core, I/O, Clock Supplies
  • Multiple Logic Supply Generator

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Design Tools

Linear Technology provides a variety of custom design simulation tools and device models to allow even novice designers to quickly and easily evaluate circuits using high performance switching regulators, amplifiers, data converters, filters and more. Please visit our Design Tools page to view and download:

  • LTspice - A powerful SPICE simulator, schematic capture and waveform viewer with enhancements and models for easing the simulation of switching regulators
  • LTpowerCAD - A complete power supply selection, synthesis and design tool
  • LTpowerPlay - A development environment supporting Linear Technology's Digital Power System Management (PSM) products
  • PScope & QuikEval - USB-based product demonstration and data acquisition system for use with our ADCs, DACs, and more
  • Linduino - Arduino compatible system for developing and distributing firmware libraries and example code
  • LinearLab Tools - A collection of Matlab and Python programs that provide direct access to Linear Technology’s data converter evaluation boards
  • And More!

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