Overview

Features and Benefits

  • 400mV Dropout Voltage
  • 700mA Output Current
  • 50μA Quiescent Current
  • No Protection Diodes Needed
  • Adjustable Output from 3.8V to 30V
  • 3.3V and 5V Fixed Output Voltages
  • Controlled Quiescent Current in Dropout
  • Shutdown
  • 16μA Quiescent Current in Shutdown
  • Stable with 3.3μF Output Capacitor
  • Reverse Battery Protection
  • No Reverse Output Current
  • Thermal Limiting
  • Surface Mount SOT-223 and DD-Pak Packages

Product Details

The LT1129/LT1129-3.3/LT1129-5 are micropower low dropout regulators with shutdown. The devices are capable of supplying 700mA of output current with a dropout voltage of 400mV at maximum output. Designed for use in battery-powered systems, the low quiescent current, 50μA operating and 16μA in shutdown, make them an ideal choice. The quiescent current does not rise in dropout as it does with many other low dropout PNP regulators.

Other features of the LT1129/LT1129-3.3/LT1129-5 include the ability to operate with small output capacitors. They are stable with only 3.3μF on the output while most older devices require between 10μF and 100μF for stability. Also the input may be connected to ground or a reverse voltage without reverse current flow from output to input. This makes the LT1129/LT1129-3.3/LT1129-5 ideal for backup power situations where the output is held high and the input is at ground or reversed. Under these conditions, only 16μA will flow from the output pin to ground. The devices are available in 5-lead TO-220, 5-lead DD-Pak and 3-lead SOT-223 packages.

Applications

  • Low Current Regulator
  • Regulator for Battery-Powered Systems
  • Post Regulator for Switching Supplies
  • 5V to 3.3V Logic Regulator

Product Lifecycle icon-recommended Production

At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.

Tools & Simulations

LTspice

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.

LTspice

Models for the following parts are available in LTspice:

LT1129
LT1129-3
LT1129-3.3
LT1129-5

Product Recommendations

LT1129 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.

Discussions

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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 Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.


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