LT3503 - 1A, 2.2MHz Step-Down Switching Regulator in 2mm x 3mm DFN


  • Wide Input Range: 3.6V to 20V
  • 5V at 1.2A from 11V to 18V Input
  • 5V at 1A from 7.2V to 18V Input
  • 3.3V at 1.2A from 8.5V to 12V Input
  • 3.3V at 1A from 5.5V to 12V Input
  • Fixed Frequency Operation: 2.2MHz
  • Output Adjustable Down to 780mV
  • Short-Circuit Robust
  • Uses Tiny Capacitors and Inductors
  • Soft-Start
  • Internally Compensated
  • Low Shutdown Current: <2µA
  • Low VCESAT Switch: 400mV at 1A
  • Thermally Enhanced, 2mm x 3mm 6-Pin DFN Low Profile Package

Typical Application

LT3503 Typical Application
LT3503 Typical Application


The LT3503 is a current mode PWM step-down DC/DC converter with an internal 1.45A power switch. The wide operating input range of 3.6V to 20V makes the LT3503 ideal for regulating power from a wide variety of sources. Its high operating frequency allows the use of tiny, low cost inductors and ceramic capacitors, resulting in low, predictable output ripple.

Cycle-by-cycle current limit provides protection against shorted outputs and soft-start eliminates input current surge during start-up. The low current (<2µA) shutdown mode provides output disconnect, enabling easy power management in battery-powered systems.


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
LT3503EDCB#PBF 2x3 DFN-6 DCB E 05-08-1715 Yes
LT3503EDCB#TRMPBF 2x3 DFN-6 DCB E 05-08-1715 Yes
LT3503EDCB#TRPBF 2x3 DFN-6 DCB E 05-08-1715 Yes

LT3503 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
LT3503EDCB#PBF 2x3 DFN-6 E $3.21 Yes
LT3503EDCB#TRMPBF 2x3 DFN-6 E $3.26 $2.30 Yes
LT3503EDCB#TRPBF 2x3 DFN-6 E $3.21 $2.25 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
DC1050A LT3503EDCB Demo Board | 4.5 ≤ VIN ≤ 20V, VOUT = 3.3V @ 1.2A $75.00
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Click here to view our complete list of demo boards


  • Automotive Battery Regulation
  • Industrial Control Supplies
  • Wall Transformer Regulation
  • Distributed Supply Regulation
  • Battery-Powered Equipment

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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

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