LT3504 - Quad 40V/1A Step-Down Switching Regulator with 100% Duty Cycle Operation


  • Wide Input Range: 3.2V to 40V
  • Four 1A Outputs
  • 100% Duty Cycle Operation
  • Resistor-Programmed Constant Frequency
  • Short-Circuit Robust
  • Wide SYNC Range: 350kHz to 2.2MHz
  • Anti-Phase Switching Reduces Ripple
  • 800mV FB Voltage
  • Independent Run/Soft-Start Pins
  • Shutdown with UVLO
  • Internal Compensation
  • Thermal Shutdown
  • Tiny 28-Lead (4mm × 5mm) Thermally Enhanced QFN Package

Typical Application

LT3504 Typical Application
LT3504 Typical Application


The LT®3504 consists of four 1A output current buck regulators. The LT3504 has a wide operating input range of 3.2V to 40V. An on-chip boost regulator allows each channel to operate up to 100% duty cycle and eliminates the need for four external charge pump circuits. The LT3504 is designed to minimize external component count and results in a simple and small application circuit.

The LT3504 operates robustly in fault conditions. Cycleby- cycle peak current limit and catch diode current limit sensing protect the part during overload conditions. Thermal shutdown protects the power switches at elevated temperatures. Soft-start helps keep the peak inductor current under control during startup.

The LT3504 also features output voltage tracking and sequencing, programmable frequency, programmable undervoltage lockout, and a power good pin to indicate when all outputs are in regulation.


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

Part Number Package Code Temp Package
LT3504EUFD#PBF 4x5 QFN-28 UFD E 05-08-1712 RoHS
LT3504EUFD#TRPBF 4x5 QFN-28 UFD E 05-08-1712 RoHS
LT3504IUFD#PBF 4x5 QFN-28 UFD I 05-08-1712 RoHS
LT3504IUFD#TRPBF 4x5 QFN-28 UFD I 05-08-1712 RoHS

LT3504 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
LT3504EUFD#PBF 4x5 QFN-28 E $5.00 $3.50 Yes
LT3504EUFD#TRPBF 4x5 QFN-28 E $3.56 Yes
LT3504IUFD#PBF 4x5 QFN-28 I $5.50 $3.85 Yes
LT3504IUFD#TRPBF 4x5 QFN-28 I $3.91 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
DC1207A LT3504 Demo Board | Quad Buck, 5.4V ≤ VIN ≤ 40V, Vout1 - Vout4 = 5V/3.3V/2.5V/1.8V @ 1A Each $175.00
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Click here to view our complete list of demo boards


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