LTC3109 - Auto-Polarity, Ultralow Voltage Step-Up Converter and Power Manager


  • Operates from Inputs as Low as ±30mV
  • Less Than ±1°C Needed Across TEG to Harvest Energy
  • Proprietary Auto-Polarity Architecture
  • Complete Energy Harvesting Power Management System
    – Selectable VOUT of 2.35V, 3.3V, 4.1V or 5V
    – 2.2V, 5mA LDO
    – Logic-Controlled Output
    – Energy Storage Capability for Operation During Power Interruption
  • Power Good Indicator
  • Uses Compact Step-up Transformers
  • Small, 20-lead (4mm × 4mm) QFN Package or 20-Lead SSOP

Typical Application

LTC3109 Typical Application
LTC3109 Typical Application


The LTC®3109 is a highly integrated DC/DC converter ideal for harvesting surplus energy from extremely low input voltage sources such as TEGs (thermoelectric generators) and thermopiles. Its unique, proprietary autopolarity topology* allows it to operate from input voltages as low as 30mV, regardless of polarity.

Using two compact step-up transformers and external energy storage elements, the LTC3109 provides a complete power management solution for wireless sensing and data acquisition. The 2.2V LDO can power an external microprocessor, while the main output can be programmed to one of four fixed voltages. The power good indicator signals that the main output is within regulation. A second output can be enabled by the host. A storage capacitor (or battery) can also be charged to provide power when the input voltage source is unavailable. Extremely low quiescent current and high efficiency maximizes the harvested energy available for the application.

The LTC3109 is available in a small, thermally enhanced 20-lead (4mm × 4mm) QFN package and a 20-lead SSOP 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
LTC3109EGN#PBF SSOP-20 GN E 05-08-1641 (GN20) Yes
LTC3109EGN#TRPBF SSOP-20 GN E 05-08-1641 (GN20) Yes
LTC3109EUF#PBF 4x4 QFN-20 UF E 05-08-1710 Yes
LTC3109EUF#TRPBF 4x4 QFN-20 UF E 05-08-1710 Yes
LTC3109IGN#PBF SSOP-20 GN I 05-08-1641 (GN20) Yes
LTC3109IGN#TRPBF SSOP-20 GN I 05-08-1641 (GN20) Yes
LTC3109IUF#PBF 4x4 QFN-20 UF I 05-08-1710 Yes
LTC3109IUF#TRPBF 4x4 QFN-20 UF I 05-08-1710 Yes

LTC3109 Package Drawing
LTC3109 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
LTC3109EGN#PBF SSOP-20 E $5.64 $3.95 Yes
LTC3109EGN#TRPBF SSOP-20 E $4.01 Yes
LTC3109EUF#PBF 4x4 QFN-20 E $5.64 $3.95 Yes
LTC3109EUF#TRPBF 4x4 QFN-20 E $4.01 Yes
LTC3109IGN#PBF SSOP-20 I $6.64 $4.65 Yes
LTC3109IGN#TRPBF SSOP-20 I $4.71 Yes
LTC3109IUF#PBF 4x4 QFN-20 I $6.64 $4.65 Yes
LTC3109IUF#TRPBF 4x4 QFN-20 I $4.71 Yes
Buy NowRequest Samples
* 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
DC1664A LTC3109EUF Demo Board | Autopolarity, Ultralow Voltage Step-Up Converter and Power Manager $150.00
Buy Now
Click here to view our complete list of demo boards


  • Remote Sensor and Radio Power
  • HVAC Systems
  • Automatic Metering
  • Building Automation
  • Predictive Maintenance
  • Industrial Wireless Sensing

Product Notifications

Please login to your MyLinear account for notifications of datasheet updates, new document releases and LTspice model announcements for your favorite products. If you do not have a MyLinear account you may Sign Up Now.

Forgot your password? Click here.
Need help? Email with questions and comments.

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

Models for the following parts are available in LTspice:

Technical Support