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  5. LT8709

Alternative Parts


Features and Benefits

  • Wide Negative Input Range: –4.5V to –80V
  • Rail-to-Rail Output Current Monitor and Control
  • Input Voltage Regulation for High Impedance Inputs
  • Power Good Indication Pin
  • MODE Pin for Forced CCM (Continuous Conduction Mode) or Pulse-Skipping/DCM (Discontinuous Conduction Mode) Operation
  • Switching Frequency Up to 750kHz
  • Easily Configurable as a Buck, Boost, Buck-Boost, or
  • Inverting Converter with a Single Feedback Pin
  • Can be Synchronized to an External Clock
  • High Gain EN/FBIN Pin Accepts Slowly Varying Input Signals
  • 20-Lead TSSOP Package

Product Details

The LT8709 is a synchronous PWM controller for negative-to-negative or negative-to-positive DC/DC conversion, with rail-to-rail output current monitor and control. The LT8709 is ideal for many local power supply designs. It can be easily configured in buck, boost, buck-boost, and inverting topologies with negative input voltages.

In addition, the LT8709’s rail-to-rail output current sense allows the part to be configured in current limited applications such as battery or capacitor charging. The PG pin is used for power good indication.

The LT8709’s switching frequency range can be set between 100kHz and 750kHz. The part may be clocked internally at a frequency set by the resistor from the RT pin to the –VIN pin, or it may be synchronized to an external clock.

The LT8709 also features innovative EN/FBIN pin circuitry that allows for slowly varying input signals and an adjustable undervoltage lockout function. The pin is also used as input voltage regulation to avoid collapsing a high impedance input supply. Additional features such as frequency foldback, thermal shutdown and soft-start are integrated. The LT8709 is available in a 20-lead TSSOP package.


  • High Power Negative Input, Negative Output Power Supplies
  • High Power Negative Input, Positive Output Power Supplies
  • Telecom Equipment Power Supplies
  • Cathodic Protection Power Supplies

Product Lifecycle icon-recommended Recommended for New Designs

This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.

Evaluation Kits (1)

Tools & Simulations


LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.

To launch ready-to-run LTspice demonstration circuits for this part:

Step 1: Download and install LTspice on your computer.

Step 2: Click on the link in the section below to download a demonstration circuit.

Step 3: If LTspice does not automatically open after clicking the link below, you can instead run the simulation by right clicking on the link and selecting “Save Target As.” After saving the file to your computer, start LTspice and open the demonstration circuit by selecting ‘Open’ from the ‘File’ menu.


Models for the following parts are available in LTspice:


Product Recommendations

LT8709 Companion Parts

Recommended Related Parts

Design Resources

ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well.  "Zero defects" for shipped products is always our goal.View our quality and reliability program and certifications for more information.

Part Number Material Declaration Reliability Data Pin/Package Drawing CAD Symbols, Footprints & 3D Models
LT8709EFE#PBF Material Declaration Reliability Data 20-Lead TSSOP w/ EP
LT8709EFE#TRPBF Material Declaration Reliability Data 20-Lead TSSOP w/ EP
LT8709IFE#PBF Material Declaration Reliability Data 20-Lead TSSOP w/ EP
LT8709IFE#TRPBF Material Declaration Reliability Data 20-Lead TSSOP w/ EP
Wafer Fabrication Data R530 Reliability Data

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Sample & Buy

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Evaluation Boards

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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.