LT8709
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LT8709

Negative Input Synchronous Multi-Topology DC/DC Controller

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LTspice LT8709 Demo Circuit - Negative Buck-Boost Regulator with Output Current Monitor & Power Good (-4.5V to -38Vin to -12Vout @ 5A) Download 5.00KB LTspice LT8709 Demo Circuit - Negative Buck Regulator with Output Current Monitor & Power Good (-16V to -30Vin to -12V @ 8.5A) Download 5.00KB LTspice LT8709 Demo Circuit - Negative Boost Regulator with Output Current Monitor & Power Good (-4.5V to -9Vin to -12V @ 4.5A) Download 6.00KB LTspice LT8709 Demo Circuit - Negative Inverting Regulator with Output Current Monitor & Power Good (-4.5V to -42Vin to 5V @ 4A) Download 5.00KB LTspice LT8709 - Switching Regulators Download 4.46 KB
Part Models 4
1ku List Price Starting From $4.37
Features
  • 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
Additional Details
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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.

Applications

  • High Power Negative Input, Negative Output Power Supplies
  • High Power Negative Input, Positive Output Power Supplies
  • Telecom Equipment Power Supplies
  • Cathodic Protection Power Supplies
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file View Data Sheet
Documentation View All Documentation
LTspice LT8709 Demo Circuit - Negative Buck-Boost Regulator with Output Current Monitor & Power Good (-4.5V to -38Vin to -12Vout @ 5A) Download 5.00KB LTspice LT8709 Demo Circuit - Negative Buck Regulator with Output Current Monitor & Power Good (-16V to -30Vin to -12V @ 8.5A) Download 5.00KB LTspice LT8709 Demo Circuit - Negative Boost Regulator with Output Current Monitor & Power Good (-4.5V to -9Vin to -12V @ 4.5A) Download 6.00KB LTspice LT8709 Demo Circuit - Negative Inverting Regulator with Output Current Monitor & Power Good (-4.5V to -42Vin to 5V @ 4A) Download 5.00KB LTspice LT8709 - Switching Regulators Download 4.46 KB
Part Models 4
1ku List Price Starting From $4.37
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LT8709

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Data Sheet

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UPDATED 03/15/2016
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LT8709: Negative Input Synchronous Multi-Topology DC/DC Controller Data Sheet

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UPDATED 03/17/2015
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LT8709: 負電圧入力、同期整流式マルチトポロジーDC/DCコントローラ データシート

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User Guide

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UPDATED 04/03/2015
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DC2148A - Demo Manual redirect icon

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Reliability Data

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UPDATED 03/26/2018
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R530 Reliability Data redirect icon

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Documentation

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Video

2017-09-18

LT8709 Video Product Brief

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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 Model Pin/Package Drawing Documentation CAD Symbols, Footprints, and 3D Models
LT8709EFE#PBF 20-Lead TSSOP w/ EP external-link
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  • Material Declaration external-link
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LT8709EFE#TRPBF 20-Lead TSSOP w/ EP external-link
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  • Material Declaration external-link
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  • Reliablity Data external-link
LT8709IFE#PBF 20-Lead TSSOP w/ EP external-link
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  • Material Declaration external-link
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  • Reliablity Data external-link
LT8709IFE#TRPBF 20-Lead TSSOP w/ EP external-link
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  • Material Declaration external-link
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  • Reliablity Data external-link

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Product Lifecycle

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Apr 6, 2022

- 22_0068

Laser Top Mark for ETSSOP and TSSOP Packages Assembled in ADPG [PNG] and UTL

LT8709EFE#PBF

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LT8709EFE#TRPBF

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LT8709IFE#PBF

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LT8709IFE#TRPBF

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Apr 6, 2022

- 22_0068

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Laser Top Mark for ETSSOP and TSSOP Packages Assembled in ADPG [PNG] and UTL

LT8709EFE#PBF

PRODUCTION

LT8709EFE#TRPBF

PRODUCTION

LT8709IFE#PBF

PRODUCTION

LT8709IFE#TRPBF

PRODUCTION

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PCN22_0068_Form

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Delta Qualification Matrix

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Software & Part Ecosystem

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RECOMMENDED FOR NEW DESIGNS

Synchronous SEPIC/Inverting/Boost Controller with Output Current Control

Evaluation Kits 1

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DC2148A

LT8709EFE Demo Board | Negative Buck-Boost, -38V ≤ VIN ≤ -4.5V; VOUT = -12V @ 5A

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DC2148A

LT8709EFE Demo Board | Negative Buck-Boost, -38V ≤ VIN ≤ -4.5V; VOUT = -12V @ 5A

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DC2148A
LT8709EFE Demo Board | Negative Buck-Boost, -38V ≤ VIN ≤ -4.5V; VOUT = -12V @ 5A
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Product Detail

Demonstration circuit 2148A features the LT8709, a negative input synchronous multi-topology DC/DC controller designed for negative input power supplies where the highest input supply voltage is ground. Examples of these circuits include negative buck, negative boost, negative buck-boost and negative inverting. The DC2148A is a negative buck-boost with an operating input voltage range from –4.5V to –38V and an output voltage of –12V, however this demo circuit can be easily reconfigured for other negative input topologies. The maximum output current for DC2148A is 5A, the switching frequency is 400kHz and the maximum efficiency with a –12V input is 91%.

Resources

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DC2148A - Demo Manual Download

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DC2148A - Schematic Download

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DC2148A - Design Files Download

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Evaluation Kits1

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DC2148A

LT8709EFE Demo Board | Negative Buck-Boost, -38V ≤ VIN ≤ -4.5V; VOUT = -12V @ 5A

Tools & Simulations 1

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.

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LT8709 Demo Circuit - Negative Buck-Boost Regulator with Output Current Monitor & Power Good (-4.5V to -38Vin to -12Vout @ 5A) Download

5.00K

spice tool Lt Spice

LT8709 Demo Circuit - Negative Buck Regulator with Output Current Monitor & Power Good (-16V to -30Vin to -12V @ 8.5A) Download

5.00K

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LT8709 Demo Circuit - Negative Boost Regulator with Output Current Monitor & Power Good (-4.5V to -9Vin to -12V @ 4.5A) Download

6.00K

spice tool Lt Spice

LT8709 Demo Circuit - Negative Inverting Regulator with Output Current Monitor & Power Good (-4.5V to -42Vin to 5V @ 4A) Download

5.00K

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LT8709 - Switching Regulators Download

4.46 K

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