LTC3770 - Fast No RSENSE Step-Down Synchronous Controller with Margining, Tracking and PLL

Features

  • Wide VIN Range: 4V to 32V
  • ±0.67% 0.6V Reference Voltage
  • Output Voltage Tracking Capability
  • Programmable Margining
  • Sense Resistor Optional
  • True Current Mode Control
  • 2% to 90% Duty Cycle at 200kHz
  • tON(MIN) ≤ 100ns
  • Phase Lock Loop Frequency Synchronization
  • Powerful Dual N-Channel MOSFET Driver
  • Adjustable Cycle-by-Cycle Current Limit
  • Adjustable Switching Frequency
  • Programmable Soft-Start
  • Current Foldback Protection (Disabled at Start-Up)
  • Output Overvoltage Protection
  • Micropower Shutdown: IQ < 30µA
  • Power Good Output Voltage Monitor Tracks the Reference Input Pin
  • Available in (5mm × 5mm) QFN and 28-Lead SSOP Packages

Typical Application

LTC3770 Typical Application
LTC3770 Typical Application

Description

The LTC3770 is a synchronous step-down switching regulator controller with output voltage up/down tracking capability and voltage margining. Its advanced functions and high accuracy reference are ideal for powering high performance server, ASIC and computer memory systems.

The LTC3770 uses a constant on-time, valley current mode control architecture to deliver very low duty factors without requiring a sense resistor. The operating frequency is selected by an external resistor and is compensated for variations in input supply voltage. An internal phase-lock loop allows the IC to be synchronized to an external clock.

Fault protection is provided by an overvoltage comparator and input undervoltage lockout. The regulator current limit is user programmable. A wide supply range allows voltages as high as 32V to be stepped down to as low as a 0.6V output. Power supply sequencing is accomplished using an external soft-start timing capacitor.

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
LTC3770EG#PBF SSOP-28 G E 05-08-1640 (G28) Yes
LTC3770EG#TRPBF SSOP-28 G E 05-08-1640 (G28) Yes
LTC3770EUH#PBF 5x5 QFN-32 UH E 05-08-1693 Yes
LTC3770EUH#TRPBF 5x5 QFN-32 UH E 05-08-1693 Yes


LTC3770 Package Drawing
LTC3770 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
LTC3770EG#PBF SSOP-28 E $4.23 $3.55 Yes
LTC3770EG#TRPBF SSOP-28 E $3.65 Yes
LTC3770EUH#PBF 5x5 QFN-32 E $4.23 $3.55 Yes
LTC3770EUH#TRPBF 5x5 QFN-32 E $3.65 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
DC774A LTC3770EUF Demo Board | Margining & Tracking, 5V ≤ VIN ≤ 28V, Vout = 2.5V @ 10A $125.00
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Click here to view our complete list of demo boards

Applications

  • Distributed Power Systems
  • Server Power Supply

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Design Tools

LTspice

LTspice® software is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. Click here to download LTspice

To launch a ready to run LTspice demonstration circuit for this part:

  • Step 1: If you have not installed LTspice on this computer, download and install LTspice
  • Step 2: Once LTspice is installed, click on the link(s) below to launch the simulation
  • Step 3: If LTspice does not automatically open after clicking the link above, you can instead run the simulation by right clicking on the link and selecting "Save Target As." After saving the file to your computer, start LTspice and open the demonstration circuit by selecting 'Open' from the 'File' menu

To explore other ready to run LTspice demonstration circuits, please visit our Demo Circuits Collection.

Models for the following parts are available in LTspice:
LTC3770

Technical Support