LM2585

ACTIVE

4-V to 40-V, 3-A step-up wide VIN flyback regulator

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Product details

Parameters

Vin (Min) (V) 4 Vin (Max) (V) 40 Vout (Min) (V) 1.23 Vout (Max) (V) 60 Switch current limit (Typ) (A) 4 Regulated outputs (#) 1 Switching frequency (Min) (kHz) 85 Switching frequency (Max) (kHz) 115 Iq (Typ) (mA) 11 Features UVLO Fixed Duty cycle (Max) (%) 98 Operating temperature range (C) -40 to 125 Rating Catalog open-in-new Find other Boost converters (integrated switch)

Package | Pins | Size

TO-220 (NDH) 5 86 mm² 10.16 x 8.47 TO-263 (KTT) 5 155 mm² 10.16 x 15.24 open-in-new Find other Boost converters (integrated switch)

Features

  • Requires Few External Components
  • Family of Standard Inductors and Transformers
  • NPN Output Switches 3 A, Can Stand Off 65 V
  • Wide Input Voltage Range: 4 V to 40 V
  • Current-mode Operation for Improved Transient Response, Line Regulation, and Current Limit
  • 100-kHz Switching Frequency
  • Internal Soft-Start Function Reduces In-rush Current During Start-up
  • Output Transistor Protected by Current Limit, Undervoltage Lockout, and Thermal Shutdown
  • System Output Voltage Tolerance of ±4% Maximum Over Line and Load Conditions
  • Create a Custom Design Using the LM2585 With the WEBENCH® Power Designer

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Description

The LM2585 series of regulators are monolithic integrated circuits specifically designed for flyback, step-up (boost), and forward converter applications. The device is available in 4 different output voltage versions: 3.3 V, 5 V, 12 V, and adjustable.

Requiring a minimum number of external components, these regulators are cost effective and simple to use. Included in the datasheet are typical circuits of boost and flyback regulators. Also listed are selector guides for diodes and capacitors and a family of standard inductors and flyback transformers designed to work with these switching regulators.

The power switch is a 3-A NPN device that can stand off 65 V. Protecting the power switch are current and thermal limiting circuits, and an undervoltage lockout circuit. This IC contains a 100-kHz fixed-frequency internal oscillator that permits the use of small magnetics. Other features include soft start mode to reduce in-rush current during start-up, current mode control for improved rejection of input voltage and output load transients and cycle-by-cycle current limiting. An output voltage tolerance of ±4%, within specified input voltages and output load conditions, is specified for the power supply system.

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Technical documentation

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Type Title Date
* Data sheet LM2585 4-V to 40-V, 3-A Step-Up Wide VIN Flyback Converter datasheet (Rev. G) May 29, 2019
Selection guide Power Management Guide 2018 (Rev. R) Jun. 25, 2018
Application note Semiconductor and IC Package Thermal Metrics (Rev. C) Apr. 19, 2016
Application note Inverted SEPIC Made SIMPLE Jul. 31, 2015
Application note Softstart Using Constant Current Constant Voltage Approach Jul. 24, 2015
Application note Working With Boost Converters Jun. 15, 2015
Application note Basic Calculation of a Boost Converter's Power Stage (Rev. C) Jan. 08, 2014
Application note AN-2162 Simple Success With Conducted EMI From DC-DC Converters (Rev. C) Apr. 24, 2013
Application note AN-1082 Adjust or Synchronize LM2586/88 Switching Frequency (Rev. B) Apr. 23, 2013
Application note AN-1149 Layout Guidelines for Switching Power Supplies (Rev. C) Apr. 23, 2013
Application note AN-1229 SIMPLE SWITCHER PCB Layout Guidelines (Rev. C) Apr. 23, 2013
Application note AN-1520 A Guide to Board Layout for Best Thermal Resistance for Exposed Packages (Rev. B) Apr. 23, 2013
Application note AN-1566 Techniques for Thermal Analysis of Switching Power Supply Designs (Rev. A) Apr. 23, 2013
Application note AN-1889 How to Measure the Loop Transfer Function of Power Supplies (Rev. A) Apr. 23, 2013
Application note AN-2155 Layout Tips for EMI Reduction in DC/ DC Converters (Rev. A) Apr. 23, 2013
Application note Input and Output Capacitor Selection Sep. 19, 2005
More literature SEM1600 Topic 4: Constructing Your Power Supply – Layout Considerations Jul. 12, 2005
Application note AN-643 EMI/RFI Board Design (Rev. B) May 03, 2004
White paper It's a Buck; It's a Boost, No! It's a Switcher! (part four) Sep. 01, 2003
Application note Understanding Boost Power Stages In Switchmode Power Supplies Mar. 04, 1999

Design & development

For additional terms or required resources, click any title below to view the detail page where available.

Design tools & simulation

SIMULATION TOOL Download
PSpice® for TI design and simulation tool
PSPICE-FOR-TI — PSpice® for TI is a design and simulation environment that helps evaluate functionality of analog circuits. This full-featured, design and simulation suite uses an analog analysis engine from Cadence®. Available at no cost, PSpice for TI includes one of the largest model libraries in the (...)
Features
  • Leverages Cadence PSpice Technology
  • Preinstalled library with a suite of digital models to enable worst-case timing analysis
  • Dynamic updates ensure you have access to most current device models
  • Optimized for simulation speed without loss of accuracy
  • Supports simultaneous analysis of multiple products
  • (...)
CALCULATION TOOL Download
Fly-Buck and Flyback Topology Selector
FLYBUCK-FLYBACK-DESIGN-CALC This tool helps a power supply engineer to select the right isolated DC-DC topology based on the specifications. Depending on the topology chosen, the calculator also recommends the right IC for the design.
Features
  • Features isolated topologies like Fly-Buck™, Fly-Buck-Boost, DCM and CCM Flyback
  • Capability to design up to 6 isolated outputs
  • Recommends ICs for desired application design
  • Incorporates loop compensation in designs
  • Compares efficiency, external component count and transformer currents for every topology (...)

CAD/CAE symbols

Package Pins Download
DDPAK/TO-263 (KTT) 5 View options
TO-220 (NDH) 5 View options

Ordering & quality

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