LTC3631 - High Efficiency, High Voltage 100mA Synchronous Step-Down Converter


  • Wide Input Voltage Range: Operation from 4.5V to 45V
  • Overvoltage Lockout Provides Protection Up to 60V
  • Internal High Side and Low Side Power Switches
  • No Compensation Required
  • 100mA Output Current
  • Low Dropout Operation: 100% Duty Cycle
  • Low Quiescent Current: 12μA
  • 0.8V ±1% Feedback Voltage Reference
  • Adjustable Peak Current Limit
  • Internal and External Soft-Start
  • Precise RUN Pin Threshold with Adjustable Hysteresis
  • 3.3V, 5V and Adjustable Output Versions
  • Only Three External Components Required for Fixed Output Versions
  • Low Profile (0.75mm) 3mm × 3mm DFN and Thermally-Enhanced MS8E Packages

Typical Application

LTC3631 Typical Application
LTC3631 Typical Application


The LTC3631 is a high voltage, high efficiency step-down DC/DC converter with internal high side and synchronous power switches that draws only 12μA typical DC supply current at no load while maintaining output voltage regulation.

The LTC3631 can supply up to 100mA load current and features a programmable peak current limit that provides a simple method for optimizing efficiency in lower current applications. The LTC3631’s combination of Burst Mode® operation, integrated power switches, low quiescent current, and programmable peak current limit provides high efficiency over a broad range of load currents.

With its wide 4.5V to 45V input range and internal overvoltage monitor capable of protecting the part from 60V surges, the LTC3631 is a robust converter suited for regulating a wide variety of power sources. Additionally, the LTC3631 includes a precise run threshold and a soft‑start feature to guarantee that power system start-up is well-controlled in any environment.

The LTC3631 is available in the thermally enhanced 3mm × 3mm DFN and MS8E packages.



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
LTC3631EDD-3.3#PBF 3x3 DFN-8 DD E 05-08-1698 Yes
LTC3631EDD-3.3#TRPBF 3x3 DFN-8 DD E 05-08-1698 Yes
LTC3631EDD-5#PBF 3x3 DFN-8 DD E 05-08-1698 Yes
LTC3631EDD-5#TRPBF 3x3 DFN-8 DD E 05-08-1698 Yes
LTC3631EDD#PBF 3x3 DFN-8 DD E 05-08-1698 Yes
LTC3631EDD#TRPBF 3x3 DFN-8 DD E 05-08-1698 Yes
LTC3631EMS8E-3.3#PBF MS-8E MS8E E 05-08-1662 Yes
LTC3631EMS8E-3.3#TRPBF MS-8E MS8E E 05-08-1662 Yes
LTC3631EMS8E-5#PBF MS-8E MS8E E 05-08-1662 Yes
LTC3631EMS8E-5#TRPBF MS-8E MS8E E 05-08-1662 Yes
LTC3631EMS8E#PBF MS-8E MS8E E 05-08-1662 Yes
LTC3631EMS8E#TRPBF MS-8E MS8E E 05-08-1662 Yes
LTC3631IDD-3.3#PBF 3x3 DFN-8 DD I 05-08-1698 Yes
LTC3631IDD-3.3#TRPBF 3x3 DFN-8 DD I 05-08-1698 Yes
LTC3631IDD-5#PBF 3x3 DFN-8 DD I 05-08-1698 Yes
LTC3631IDD-5#TRPBF 3x3 DFN-8 DD I 05-08-1698 Yes
LTC3631IDD#PBF 3x3 DFN-8 DD I 05-08-1698 Yes
LTC3631IDD#TRPBF 3x3 DFN-8 DD I 05-08-1698 Yes
LTC3631IMS8E-3.3#PBF MS-8E MS8E I 05-08-1662 Yes
LTC3631IMS8E-3.3#TRPBF MS-8E MS8E I 05-08-1662 Yes
LTC3631IMS8E-5#PBF MS-8E MS8E I 05-08-1662 Yes
LTC3631IMS8E-5#TRPBF MS-8E MS8E I 05-08-1662 Yes
LTC3631IMS8E#PBF MS-8E MS8E I 05-08-1662 Yes
LTC3631IMS8E#TRPBF MS-8E MS8E I 05-08-1662 Yes

LTC3631 Package Drawing
LTC3631 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
LTC3631EDD-3.3#PBF 3x3 DFN-8 E $4.22 $2.95 Yes
LTC3631EDD-3.3#TRPBF 3x3 DFN-8 E $3.01 Yes
LTC3631EDD-5#PBF 3x3 DFN-8 E $4.22 $2.95 Yes
LTC3631EDD-5#TRPBF 3x3 DFN-8 E $3.01 Yes
LTC3631EDD#PBF 3x3 DFN-8 E $4.22 $2.95 Yes
LTC3631EDD#TRPBF 3x3 DFN-8 E $3.01 Yes
LTC3631EMS8E-3.3#PBF MS-8E E $4.22 $2.95 Yes
LTC3631EMS8E-3.3#TRPBF MS-8E E $3.01 Yes
LTC3631EMS8E-5#PBF MS-8E E $4.22 $2.95 Yes
LTC3631EMS8E-5#TRPBF MS-8E E $3.01 Yes
LTC3631EMS8E#PBF MS-8E E $4.22 $2.95 Yes
LTC3631EMS8E#TRPBF MS-8E E $3.01 Yes
LTC3631IDD-3.3#PBF 3x3 DFN-8 I $4.84 $3.39 Yes
LTC3631IDD-3.3#TRPBF 3x3 DFN-8 I $3.45 Yes
LTC3631IDD-5#PBF 3x3 DFN-8 I $4.84 $3.39 Yes
LTC3631IDD-5#TRPBF 3x3 DFN-8 I $3.45 Yes
LTC3631IDD#PBF 3x3 DFN-8 I $4.84 $3.39 Yes
LTC3631IDD#TRPBF 3x3 DFN-8 I $3.45 Yes
LTC3631IMS8E-3.3#PBF MS-8E I $4.84 $3.39 Yes
LTC3631IMS8E-3.3#TRPBF MS-8E I $3.45 Yes
LTC3631IMS8E-5#PBF MS-8E I $4.84 $3.39 Yes
LTC3631IMS8E-5#TRPBF MS-8E I $3.45 Yes
LTC3631IMS8E#PBF MS-8E I $4.84 $3.39 Yes
LTC3631IMS8E#TRPBF MS-8E I $3.45 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
DC1499A LTC3631EDD Demo Board | 60V Transients, 4.5V ≤ VIN ≤ 45V, VOUT = 1.8V/3.3V/5V @ 100mA $100.00
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  • 4mA to 20mA Current Loops
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  • Distributed Power Systems
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  • Battery-Operated Devices
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