SIMPLE SWITCHER® 4V to 40V, 5A Step-Up Wide Vin Flyback Regulator

SIMPLE SWITCHER® 4V to 40V, 5A Step-Up Wide Vin Flyback Regulator - LM2587


The LM2587 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: 3.3V, 5.0V, 12V, 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 5.0A NPN device that can stand-off 65V. 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 ensured for the power supply system.


  • Requires Few External Components
  • Family of Standard Inductors and Transformers
  • NPN Output Switches 5.0A, can Stand Off 65V
  • Wide Input Voltage Range: 4V to 40V
  • 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, Under Voltage Lockout, and Thermal Shutdown
  • System Output Voltage Tolerance of ±4% Max Over Line and Load Conditions

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Parametrics Compare all products in Boost Converter (Integrated Switch)

Vin (Min) (V)
Vin (Max) (V)
Vout (Min) (V)
Vout (Max) (V)
Switch Current Limit (Typ) (A)
Regulated Outputs (#)
Switching Frequency (Min) (kHz)
Switching Frequency (Max) (kHz)
Iq (Typ) (mA)
Duty Cycle (Max) (%)
Operating Temperature Range (C)
Package Group
LM2587 LM2585 LM2586 LM5000
4    4    4    3.1   
40    40    40    40   
1.23    1.23    1.23    1.259   
60    60    60    75   
6.5    4    4    2   
1    1    1    1   
85    85    75    300   
115    115    125    1300   
11    11    11    2.1   
N/A      Enable
Frequency Synchronization   
98    98    98    90   
-40 to 125    -40 to 125    -40 to 125    -40 to 125   
Catalog    Catalog    Catalog    Catalog   
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WEBENCH® Designer LM2587

  Min   Max Range
Vin  V 4.0 to 40.0V
Vout  V 1.23 to 300V
Iout  A ≤ 5A
Ambient Temp  °C -40 to 125°C

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