Overview

Features and Benefits

  • Wide Input Voltage Range 3.5V to 30V
  • Low Quiescent Current: 7mA
  • Internal 4A Switch
  • Very Few External Parts Required
  • Self Protected Against Overloads
  • Shutdown Mode Draws Only 100µA Supply Current
  • Flyback Regulated Mode Has Fully Floating Outputs
  • Comes in Standard 5-Pin Package
  • Can Be Externally Synchronized (See LT1072 Data Sheet)

Product Details

The LT1271 and LT1269 are monolithic high power switching regulators. Identical to the popular LT1070, except for switching frequency (LT1271 = 60kHz, LT1269 = 100kHz) and slightly lower switch current, they can be operated in all standard switching configurations including buck, boost, flyback and inverting. A high current, high efficiency switch is included on the die along with all oscillator, control and protection circuitry. Integration of all functions allows the LT1271/LT1269 to be built in a standard TO-220 power package. This makes them extremely easy to use and provides “bust proof” operation similar to that obtained with 3-pin linear regulators.

The LT1271/LT1269 operate with supply voltages from 3.5V to 30V, and draw only 7mA quiescent current. By utilizing current mode switching techniques, they provides excellent AC and DC load and line regulation.

A patented adaptive antisat switch drive allows very wide ranging load currents with no loss in efficiency. An externally activated shutdown mode reduces total supply current to 100µA typical for standby operation.

User Note: This data sheet is only intended to provide specifications, graphs, and a general functional description of the LT1271/LT1269. Application circuits are included to show the capability of the LT1271/LT1269. A complete design manual (AN-19) should be obtained to assist in developing new designs. This manual contains a comprehensive discussion of both the LT1070 and the external components used with it, as well as complete formulas for calculating the values of these components. The manual can also be used for the LT1271/LT1269 by factoring in the higher switch current rating and higher operating frequency.

Applications

  • Boost Converter
  • High Efficiency Buck Converter
  • PC Power Supply with Multiple Outputs
  • Battery Up-Converter
  • Negative-to-Positive Converter

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.

LTspice

Models for the following parts are available in LTspice:

LT1271

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.

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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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