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LM3481

ACTIVE

2.97V to 48V High-Efficiency Controller for Boost, SEPIC and Flyback

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Data sheet

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Same functionality with different pin-out to the compared device
LM5155 ACTIVE 2.2-MHz wide VIN, 1.5-A MOSFET driver, non-synchronous boost controller Up to 2.2-MHz Fsw, higher efficiency and up to 45-V input operating voltage.
LM5156H ACTIVE 2.2-MHz wide VIN nonsynchronous boost, flyback, & SEPIC controller with dual random spread spectrum A newer device with up to 2.2-MHz Fsw, higher efficiency, spread spectrum, up to 60-V input operating voltage, and an HTSSOP package.

LM3481

ACTIVE
Data sheet Order now

Product details

Vin (min) (V) 2.97 Vin (max) (V) 48 Iout (max) (A) 10 Operating temperature range (°C) -40 to 125 Control mode current mode Topology Boost, Flyback, Forward, SEPIC Rating Catalog Vout (min) (V) 1.26 Vout (max) (V) 500 Iq (typ) (A) 0.0037 Duty cycle (max) (%) 85
Vin (min) (V) 2.97 Vin (max) (V) 48 Iout (max) (A) 10 Operating temperature range (°C) -40 to 125 Control mode current mode Topology Boost, Flyback, Forward, SEPIC Rating Catalog Vout (min) (V) 1.26 Vout (max) (V) 500 Iq (typ) (A) 0.0037 Duty cycle (max) (%) 85
VSSOP (DGS) 10 14.7 mm² 3 x 4.9
  • 10-Lead VSSOP package
  • Internal push-pull driver with 1-A peak current capability
  • Current limit and thermal shutdown
  • Frequency compensation optimized with a capacitor and a resistor
  • Internal soft start
  • Current mode operation
  • Adjustable undervoltage lockout with hysteresis
  • Pulse skipping at light loads
  • Key specifications
    • Wide supply voltage range of 2.97 V to 48 V
    • 100-kHz to 1-MHz Adjustable and synchronizable clock frequency
    • ±1.5% (over temperature) internal reference
    • 10-µA shutdown current (over temperature)
  • Create a custom design using the LM3481 with the WEBENCH Power Designer
  • 10-Lead VSSOP package
  • Internal push-pull driver with 1-A peak current capability
  • Current limit and thermal shutdown
  • Frequency compensation optimized with a capacitor and a resistor
  • Internal soft start
  • Current mode operation
  • Adjustable undervoltage lockout with hysteresis
  • Pulse skipping at light loads
  • Key specifications
    • Wide supply voltage range of 2.97 V to 48 V
    • 100-kHz to 1-MHz Adjustable and synchronizable clock frequency
    • ±1.5% (over temperature) internal reference
    • 10-µA shutdown current (over temperature)
  • Create a custom design using the LM3481 with the WEBENCH Power Designer

The LM3481 device is a versatile Low-Side N-FET high-performance controller for switching regulators. The device is designed for use in boost, SEPIC and flyback converters and topologies requiring a low-side FET as the primary switch. The LM3481 device can be operated at very high switching frequencies to reduce the overall solution size. The switching frequency of the LM3481 device can be adjusted to any value between 100 kHz and 1 MHz by using a single external resistor or by synchronizing it to an external clock. Current mode control provides superior bandwidth and transient response in addition to cycle-by-cycle current limiting. Current limit can be programmed with a single external resistor.

The LM3481 device has built-in protection features such as thermal shutdown, short-circuit protection and overvoltage protection. Power-saving shutdown mode reduces the total supply current to 5 µA and allows power supply sequencing. Internal soft start limits the inrush current at start-up. Integrated current slope compensation simplifies the design and, if needed for specific applications, can be increased using a single resistor.

The LM3481 device is a versatile Low-Side N-FET high-performance controller for switching regulators. The device is designed for use in boost, SEPIC and flyback converters and topologies requiring a low-side FET as the primary switch. The LM3481 device can be operated at very high switching frequencies to reduce the overall solution size. The switching frequency of the LM3481 device can be adjusted to any value between 100 kHz and 1 MHz by using a single external resistor or by synchronizing it to an external clock. Current mode control provides superior bandwidth and transient response in addition to cycle-by-cycle current limiting. Current limit can be programmed with a single external resistor.

The LM3481 device has built-in protection features such as thermal shutdown, short-circuit protection and overvoltage protection. Power-saving shutdown mode reduces the total supply current to 5 µA and allows power supply sequencing. Internal soft start limits the inrush current at start-up. Integrated current slope compensation simplifies the design and, if needed for specific applications, can be increased using a single resistor.
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Technical documentation

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Type Title Date
* Data sheet LM3481High-Efficiency Controller for Boost, SEPIC and Flyback DC/DC Converters datasheet (Rev. G) PDF | HTML 10 Sep 2018
Application note AN-1286 Compensation for the LM3478 Boost Controller (Rev. D) PDF | HTML 09 Aug 2022
Application note LM34xx How to Design Flyback Converter with LM3481 Boost Controller (Rev. A) 08 Apr 2019
Selection guide Power Management Guide 2018 (Rev. R) 25 Jun 2018
Technical article Eliminating noise from the factory floor PDF | HTML 29 Sep 2016
EVM User's guide LM3481 flyback EVM User's Guide 19 May 2016
Technical article How do you generate a high voltage from a single cell Li Ion battery? PDF | HTML 11 Dec 2015
Application note Softstart Using Constant Current Constant Voltage Approach 24 Jul 2015
Technical article Portable speaker power: Making the bass possible PDF | HTML 12 May 2015
Application note Demystifying Type II and Type III Compensators Using Op-Amp and OTA for DC/DC Co 11 Jul 2014
EVM User's guide AN-1756 LM3481 Evaluation Board (Rev. A) 01 May 2013
User guide AN-2094 LM3481 SEPIC Evaluation Board (Rev. A) 25 Apr 2013
Application note AN-1484 Designing A SEPIC Converter (Rev. E) 23 Apr 2013
Application note AN-1990 Compensation for Current Mode Control SEPIC Converters (Rev. A) 23 Apr 2013
Application note Modeling & Design of Current Mode Control Boost Converters (Rev. B) 23 Apr 2013
User guide 330mW AC or DC Tiny Flyback Converter Power Supply Reference Design User Guide 27 Jan 2012

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