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LM2585

ACTIVE

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

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Data sheet

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LM5158 ACTIVE 3-A, 85-V, 2.2-MHz wide VIN boost, flyback, & SEPIC converter with dual random spread spectrum Newer device with higher Vout capability and higher switch current

LM2585

ACTIVE
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Product details

Rating Catalog Topology Boost, Flyback, Forward, SEPIC Vin (max) (V) 40 Vin (min) (V) 4 Vout (max) (V) 60 Vout (min) (V) 1.23 Switch current limit (typ) (A) 4 Features Nonsynchronous rectification, UVLO fixed Control mode current mode Operating temperature range (°C) -40 to 125 Iq (typ) (A) 0.011 Duty cycle (max) (%) 98
Rating Catalog Topology Boost, Flyback, Forward, SEPIC Vin (max) (V) 40 Vin (min) (V) 4 Vout (max) (V) 60 Vout (min) (V) 1.23 Switch current limit (typ) (A) 4 Features Nonsynchronous rectification, UVLO fixed Control mode current mode Operating temperature range (°C) -40 to 125 Iq (typ) (A) 0.011 Duty cycle (max) (%) 98
TO-263 (KTT) 5 154.8384 mm² (10.16 mm × 15.24 mm) TO-220 (NDH) 5 86.0552 mm² (10.16 mm × 8.47 mm)
  • 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
  • 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

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.

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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Top documentation Type Title Format options Date
* Data sheet LM2585 4-V to 40-V, 3-A Step-Up Wide VIN Flyback Converter datasheet (Rev. G) PDF | HTML May 29, 2019
Application note Semiconductor and IC Package Thermal Metrics (Rev. D) PDF | HTML Mar 25, 2024
Application note Basic Calculation of a Boost Converter's Power Stage (Rev. D) PDF | HTML Oct 28, 2022
Selection guide Power Management Guide 2018 (Rev. R) Jun 25, 2018
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 AN-2162 Simple Success With Conducted EMI From DC-DC Converters (Rev. C) Apr 24, 2013
Application note AN-1566 Techniques for Thermal Analysis of Switching Power Supply Designs (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 AN-1229 SIMPLE SWITCHER PCB Layout Guidelines (Rev. C) Apr 23, 2013
Application note AN-1149 Layout Guidelines for Switching Power Supplies (Rev. C) 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-1082 Adjust or Synchronize LM2586/88 Switching Frequency (Rev. B) 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 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 3, 2004
White paper It's a Buck; It's a Boost, No! It's a Switcher! (part four) Sep 1, 2003
Application note Understanding Boost Power Stages In Switchmode Power Supplies Mar 4, 1999

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