LT3508 - Dual Monolithic 1.4A Step-Down Switching Regulator

Features

  • Wide Input Voltage Range: 3.7V to 36V
  • Two 1.4A Output Switching Regulators with Internal Power Switches
  • Adjustable 250kHz to 2.5MHz Switching Frequency
  • Synchronizable over the Full Frequency Range
  • Anti-Phase Switching Reduces Ripple
  • Uses Small Inductors and Ceramic Capacitors
  • Accurate Programmable Undervoltage Lockout
  • Independent Tracking, Soft-Start and Power Good Circuits Ease Supply Sequencing
  • Output Adjustable Down to 800mV
  • Small 4mm × 4mm 24-Pin QFN or 16-Pin Thermally Enhanced TSSOP Surface Mount Packages
Designed for Automotive and Transportation Applications
AEC-Q100 generic family data available for specific packages


Typical Application

LT3508 Typical Application
LT3508 Typical Application

Description

The LT3508 is a dual current mode PWM step-down DC/DC converter with internal power switches capable of generating two 1.4A outputs. The wide input voltage range of 3.7V to 36V makes the LT3508 suitable for regulating power from a wide variety of sources, including automotive batteries, 24V industrial supplies and unregulated wall adapters. Both converters are synchronized to a single oscillator programmable up to 2.5MHz and run with opposite phases, reducing input ripple current. Its high operating frequency allows the use of small, low cost inductors and ceramic capacitors, resulting in low, predictable output ripple. Each regulator has independent tracking and softstart circuits and generates a power good signal when its output is in regulation, easing power supply sequencing and interfacing with microcontrollers and DSPs.

Cycle-by-cycle current limit, frequency foldback and thermal shutdown provide protection against shorted outputs, and soft-start eliminates input current surge during startup. The low current (<2µA) shutdown mode enables easy power management in battery-powered systems.

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
LT3508EFE#PBF TSSOP-16 FE E 05-08-1663 (BA) Yes
LT3508EFE#TRPBF TSSOP-16 FE E 05-08-1663 (BA) Yes
LT3508EUF#PBF 4x4 QFN-24 UF E 05-08-1697 Yes
LT3508EUF#TRPBF 4x4 QFN-24 UF E 05-08-1697 Yes
LT3508HFE#PBF TSSOP-16 FE H 05-08-1663 (BA) Yes
LT3508HFE#TRPBF TSSOP-16 FE H 05-08-1663 (BA) Yes
LT3508HUF#PBF 4x4 QFN-24 UF H 05-08-1697 Yes
LT3508HUF#TRPBF 4x4 QFN-24 UF H 05-08-1697 Yes
LT3508IFE#PBF TSSOP-16 FE I 05-08-1663 (BA) Yes
LT3508IFE#TRPBF TSSOP-16 FE I 05-08-1663 (BA) Yes
LT3508IUF#PBF 4x4 QFN-24 UF I 05-08-1697 Yes
LT3508IUF#TRPBF 4x4 QFN-24 UF I 05-08-1697 Yes


LT3508 Package Drawing
LT3508 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
LT3508EFE#PBF TSSOP-16 E $5.00 $3.50 Yes
LT3508EFE#TRPBF TSSOP-16 E $3.56 Yes
LT3508EUF#PBF 4x4 QFN-24 E $4.79 $3.35 Yes
LT3508EUF#TRPBF 4x4 QFN-24 E $3.41 Yes
LT3508HFE#PBF TSSOP-16 H $6.36 $4.45 Yes
LT3508HFE#TRPBF TSSOP-16 H $4.51 Yes
LT3508HUF#PBF 4x4 QFN-24 H $6.10 $4.27 Yes
LT3508HUF#TRPBF 4x4 QFN-24 H $4.33 Yes
LT3508IFE#PBF TSSOP-16 I $6.00 $4.20 Yes
LT3508IFE#TRPBF TSSOP-16 I $4.26 Yes
LT3508IUF#PBF 4x4 QFN-24 I $5.74 $4.02 Yes
LT3508IUF#TRPBF 4x4 QFN-24 I $4.08 Yes
Buy NowRequest Samples
* 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
DC1060A LT3508EFE/LT3508EUF Demo Board $125.00
Buy Now
Click here to view our complete list of demo boards

Designed for Automotive and Transportation Applications

Please contact your local sales representative for more information regarding reliability reports and AEC-Q100 data or to inquire about parts that are not included. For more information, view our Automotive and Transportation page

Part Number Package Temp Price
(1-99)
Price
(1k)*
RoHS
LT3508HFE#PBF TSSOP-16 H $6.36 $4.45 Yes
LT3508HFE#TRPBF TSSOP-16 H $4.51 Yes
LT3508HUF#PBF 4x4 QFN-24 H $6.10 $4.27 Yes
LT3508HUF#TRPBF 4x4 QFN-24 H $4.33 Yes
LT3508IFE#PBF TSSOP-16 I $6.00 $4.20 Yes
LT3508IFE#TRPBF TSSOP-16 I $4.26 Yes
LT3508IUF#PBF 4x4 QFN-24 I $5.74 $4.02 Yes
LT3508IUF#TRPBF 4x4 QFN-24 I $4.08 Yes
Buy NowRequest Samples
* 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.

Applications

  • Automotive
  • DSP Power Supplies
  • Wall Transformer Regulation
  • DSL and Cable Modems
  • PCI Express

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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:
LT3508

LTpowerCAD

The LTpowerCAD design tool is a complete power supply design tool program that can significantly ease the tasks of power supply design. It guides users to a solution, selects power stage components, provides detailed power efficiency, shows quick loop bode plot stability and load transient analysis, and can export a final design to LTspice for simulation. Click here to download LTpowerCAD

Design tools for the following parts are available in LTpowerCAD:
LT3508

Technical Support