LT3742 - Dual, 2-Phase Step-Down Switching Controller


  • Wide Input Voltage Range: 4V to 30V
  • Wide Output Voltage Range: 0.8V to VIN
  • Low Shutdown IQ: 20μA
  • Out-of-Phase Controllers Reduce Required Input Capacitance and Power Supply Induced Noise
  • 0.8V ±1.5% Voltage Reference
  • 500kHz Current Mode Fixed Frequency Operation
  • Internal Boost Converter Provides Bias Rail for N-Channel MOSFET Gate Drive
  • Power Good Voltage Monitor for Each Output
  • Programmable Soft-Start
  • 24-Lead 4mm × 4mm × 0.75mm Package

Typical Application

LT3742 Typical Application
LT3742 Typical Application


The LT3742 is a dual step-down DC/DC switching regulator controller that drives high side N-channel power MOSFETs. A 500kHz fixed frequency current mode architecture provides fast transient response with simple loop compensation components and cycle-by-cycle current limiting. The output stages of the two controllers operate 180° out of phase to reduce the input ripple current, minimizing the noise induced on the input supply, and allowing less input capacitance.

An internal boost regulator generates a bias rail of VIN + 7V to provide gate drive for the N-channel MOSFETs allowing low dropout and 100% duty cycle operation. The LT3742 can be used for applications where both controllers need to operate independently, or where both controllers are used to provide a single higher current output.

The device is available in a thermally enhanced 4mm × 4mm QFN package.


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
LT3742EUF#PBF 4x4 QFN-24 UF E 05-08-1697 Yes
LT3742EUF#TRPBF 4x4 QFN-24 UF E 05-08-1697 Yes

LT3742 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
LT3742EUF#PBF 4x4 QFN-24 E $3.29 $2.30 Yes
LT3742EUF#TRPBF 4x4 QFN-24 E $2.36 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
DC927A LT3742EFE Demo Board | 5.5V ≤ VIN ≤ 28V, Vout1 = 5V @ 4A, Vout2 = 3.3V @ 4A $125.00
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Click here to view our complete list of demo boards


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Design Tools


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:


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:

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