LTC3873-5 - No RSENSE Constant Frequency Current Mode Boost/Flyback/SEPIC DC/DC Controller


  • VIN and VOUT Limited Only by External Components
  • Internal or Programmable External Soft-Start
  • Constant Frequency 200kHz Operation
  • Adjustable Current Limit
  • Current Sense Resistor Optional
  • ±1.5% Voltage Reference Accuracy
  • Current Mode Operation for Excellent Line and Load Transient Response
  • 4.1V Undervoltage Threshold for Logic Level
    MOSFET Applications
  • Low Quiescent Current: 300µA
  • Low Profile (1mm) ThinSOT™ and (0.75mm) 2mm × 3mm DFN Package

Typical Application

LTC3873-5 Typical Application
LTC3873-5 Typical Application


The LTC3873-5 is a constant frequency current mode controller for boost, flyback or SEPIC DC/DC converters designed to drive an N-channel MOSFET for high input and output voltage converter applications.

The LTC3873-5 provides ±1.5% output voltage accuracy and consumes only 300μA quiescent current during normal operation and only 50μA during micropower start-up. Using a 9.3V internal shunt regulator, the LTC3873-5 can be powered from a high input voltage through a resistor or it can be powered directly from a low impedance DC voltage of 9V or less. Soft-start can be programmed using an external capacitor.

The LTC3873-5 is available in 8-lead ThinSOT and 2mm × 3mm DFN packages.

VCC UV+ 8.4V 3.9V
VCC UV- 4V 2.9V


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
LTC3873EDDB-5#PBF 3x2 DFN-8 DDB E 05-08-1702 Yes
LTC3873EDDB-5#TRMPBF 3x2 DFN-8 DDB E 05-08-1702 Yes
LTC3873EDDB-5#TRPBF 3x2 DFN-8 DDB E 05-08-1702 Yes
LTC3873ETS8-5#PBF SOT-23 TS8 E 05-08-1637 Yes
LTC3873ETS8-5#TRMPBF SOT-23 TS8 E 05-08-1637 Yes
LTC3873ETS8-5#TRPBF SOT-23 TS8 E 05-08-1637 Yes
LTC3873IDDB-5#PBF 3x2 DFN-8 DDB I 05-08-1702 Yes
LTC3873IDDB-5#TRMPBF 3x2 DFN-8 DDB I 05-08-1702 Yes
LTC3873IDDB-5#TRPBF 3x2 DFN-8 DDB I 05-08-1702 Yes
LTC3873ITS8-5#PBF SOT-23 TS8 I 05-08-1637 Yes
LTC3873ITS8-5#TRMPBF SOT-23 TS8 I 05-08-1637 Yes
LTC3873ITS8-5#TRPBF SOT-23 TS8 I 05-08-1637 Yes

LTC3873-5 Package Drawing
LTC3873-5 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
LTC3873EDDB-5#PBF 3x2 DFN-8 E $1.79 Yes
LTC3873EDDB-5#TRMPBF 3x2 DFN-8 E $1.79 $1.30 Yes
LTC3873EDDB-5#TRPBF 3x2 DFN-8 E $1.79 $1.25 Yes
LTC3873ETS8-5#PBF SOT-23 E $1.79 Yes
LTC3873ETS8-5#TRMPBF SOT-23 E $1.79 $1.30 Yes
LTC3873ETS8-5#TRPBF SOT-23 E $1.79 $1.25 Yes
LTC3873IDDB-5#PBF 3x2 DFN-8 I $1.84 Yes
LTC3873IDDB-5#TRMPBF 3x2 DFN-8 I $1.84 $1.34 Yes
LTC3873IDDB-5#TRPBF 3x2 DFN-8 I $1.84 $1.29 Yes
LTC3873ITS8-5#PBF SOT-23 I $1.84 Yes
LTC3873ITS8-5#TRMPBF SOT-23 I $1.84 $1.34 Yes
LTC3873ITS8-5#TRPBF SOT-23 I $1.84 $1.29 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.

Click here to view our complete list of demo boards


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