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AC/DC & DC/DC controllers (external FET)

LM3478

ACTIVE

2.97~40V Wide Input Range Boost/SEPIC/Flyback DC-DC Controller

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Data sheet

A newer version of this product is available

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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 A newer device with 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.

LM3478

ACTIVE
Data sheet Order now

Product details

Vin (min) (V) 2.97 Vin (max) (V) 40 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 Features Adjustable current limit, Enable, Frequency synchronization, Light Load Efficiency, Nonsynchronous rectification, Pre-Bias Start-Up Iq (typ) (µA) 2700 Duty cycle (max) (%) 100
Vin (min) (V) 2.97 Vin (max) (V) 40 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 Features Adjustable current limit, Enable, Frequency synchronization, Light Load Efficiency, Nonsynchronous rectification, Pre-Bias Start-Up Iq (typ) (µA) 2700 Duty cycle (max) (%) 100
SOIC (D) 8 29.4 mm² 4.9 x 6 VSSOP (DGK) 8 14.7 mm² 3 x 4.9
  • 8-lead VSSOP-8 and SOIC-8 packages
  • 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
  • Undervoltage Lockout With Hysteresis
  • Create a Custom Design Using the LM3478 with the WEBENCH Power Designer
  • 8-lead VSSOP-8 and SOIC-8 packages
  • 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
  • Undervoltage Lockout With Hysteresis
  • Create a Custom Design Using the LM3478 with the WEBENCH Power Designer

The LM3478 is a versatile Low-Side N-Channel MOSFET controller for switching regulators. It is suitable for use in topologies requiring a low side MOSFET, such as boost, flyback, SEPIC, etc. Moreover, the LM3478 can be operated at extremely high switching frequency in order to reduce the overall solution size. The switching frequency of the LM3478 can be adjusted to any value between 100 kHz and 1 MHz by using a single external resistor. Current mode control provides superior bandwidth and transient response, besides cycle-by-cycle current limiting. Output current can be programmed with a single external resistor.

The LM3478 has built-in features such as thermal shutdown, short-circuit protection, over voltage protection, etc. 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.

The LM3478 is a versatile Low-Side N-Channel MOSFET controller for switching regulators. It is suitable for use in topologies requiring a low side MOSFET, such as boost, flyback, SEPIC, etc. Moreover, the LM3478 can be operated at extremely high switching frequency in order to reduce the overall solution size. The switching frequency of the LM3478 can be adjusted to any value between 100 kHz and 1 MHz by using a single external resistor. Current mode control provides superior bandwidth and transient response, besides cycle-by-cycle current limiting. Output current can be programmed with a single external resistor.

The LM3478 has built-in features such as thermal shutdown, short-circuit protection, over voltage protection, etc. 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.
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Technical documentation

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Type Title Date
* Data sheet LM3478 High-Efficiency Low-Side N-Channel Controller for Switching Regulator datasheet (Rev. X) PDF | HTML 28 Feb 2017
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
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
User guide AN-1204 LM3478/LM3488 Evaluation Board (Rev. A) 30 Oct 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
More literature Die D/S LM3478 MDC Hi Efficiency Low-Side N-Chan Controller For Switching Reg 25 Sep 2012

Design & development

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

Evaluation board

LM3478EVAL — High Efficiency Low-Side N-Channel Controller for Switching Regulator

High Efficiency Low-Side N-Channel Controller for Switching Regulator

User guide: PDF
Not available on TI.com
Simulation model

LM3478 PSpice Average Model

SNVMBH8.ZIP (170 KB) - PSpice Model
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Simulation model

LM3478 PSpice Transient Model (Rev. C)

SNVMAW8C.ZIP (124 KB) - PSpice Model
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Simulation model

LM3478 TINA-TI Average SEPIC Reference Design (Rev. A)

SNVMB83A.TSC (98 KB) - TINA-TI Reference Design
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Simulation model

LM3478 TINA-TI Boost and SEPIC Average Spice Model (Rev. A)

SNVMB84A.ZIP (9 KB) - TINA-TI Spice Model
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Simulation model

LM3478 Unencrypted PSpice Average Model

SNVMBL8.ZIP (2 KB) - PSpice Model
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Simulation model

LM3478 Unencrypted PSpice Transient Model (Rev. B)

SNVMAW9B.ZIP (5 KB) - PSpice Model
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Calculation tool

FLYBUCK-FLYBACK-DESIGN-CALC — Flybuck / Flyback Calculator

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.

Supported products & hardware

Supported products & hardware

Products
AC/DC & DC/DC controllers (external FET)
LM3017 — High Efficiency Low-Side Controller with True Shutdown LM3478 — 2.97~40V Wide Input Range Boost/SEPIC/Flyback DC-DC Controller LM3478Q-Q1 — 40-V wide VIN low-side N-channel controller for switching regulators with 10-µA shutdown current LM3481 — 2.97V to 48V High-Efficiency Controller for Boost, SEPIC and Flyback LM3481-Q1 — 2.97-V to 48-V high-efficiency controller for boost, SEPIC and flyback, AEC-Q100 qualified LM3488 — 2.97V to 40V Wide Vin Low-Side N-Channel Controller for Switching Regulators LM3488Q-Q1 — 40-V wide VIN low-side N-channel controller for switching regulators with 5-µA shutdown current LM3524D — 40V, 0.2A 350KHz PWM controller LM3578A — 2-V to 40-VIN switching regulators in buck, boost, terminal, depending upon the application LM5020 — 13-100V Wide Vin, Current Mode PWM Boost, Flyback, Sepic Controller LM5022 — 6-60V Wide Vin, current mode boost, SEPIC and Flyback controller TL1451 — Dual Pulse-Width-Modulation Control Circuit TL1451A — 3.6V to 50V dual channel controller with Wide input voltage range TL1451A-EP — Enhanced Product Dual Pulse-Width-Modulation Control Circuits TL1451A-Q1 — 3.6-V to 50-V dual-channel PWM controller, AEC-Q100 qualified TL5001 — PWM Controller with wide input range, with ±5% tolerance on reference, operation –20°C to 85°C TL5001A — PWM Controller with wide input range, with ±3% tolerance on reference, operation –20°C to 85°C TL5001A-Q1 — PWM Controller with wide input range, with ±3% tolerance on reference, operation –20°C to 85°C TL5001M — PWM Controller with wide input range, with ±5% tolerance on reference, operation –55°C to 125°C TPS40210-Q1 — 4.5-V to 52-V wide input range current mode boost controller with 700-mV reference voltage TPS40211-Q1 — 4.5-V to 52-V wide input range current mode boost controller with 260-mV reference voltage TPS43000 — Multi-Topology (buck, boost, sepic) High Frequency DC/DC Controller TPS55010 — 2.95V To 6V Input, 2W, Isolated DC/DC Converter with Integrated FETS UC2572 — Negative output Flyback pulse width modulator
AC/DC & DC/DC converters (integrated FET)
LM25017 — 7.5-48V Wide Vin, 650mA Constant On-Time Synchronous Buck Regulator LM25018 — 7.5-48V Wide Vin, 300mA Constant On-Time Synchronous Buck Regulator LM25019 — 7.5-48V Wide Vin, 100mA Constant On-Time Synchronous Buck Regulator LM2577 — 3.5-V to 40-V, 3-A low component count step-up regulator LM2585 — 4-V to 40-V, 3-A step-up wide VIN flyback regulator LM2586 — 4-V to 40-V, 3-A step-up wide VIN flyback regulator with frequency synchronization LM2587 — 4V to 40V, 5A Step-Up Wide Vin Flyback Regulator LM2588 — 4-V to 40-V, 5-A step-up wide VIN flyback regulator with frequency synchronization LM2621 — 1.2V to 14V input voltage, 1A load current, step-up DC-DC LM2623 — 0.8V to 14V input voltage, 2A load current, step-up DC-DC LM2623-Q1 — 0.8-V to 14-V input voltage, 2-A load current, step-up DC/DC, AEC-Q100 qualified LM2735 — 520kHz/1.6MHz space efficient boost and SEPIC DC-DC regulator LM2735-Q1 — 520-kHz, 1.6-MHz space efficient boost and SEPIC DC/DC regulator, AEC-Q100 qualified LM34925 — 7.5-100V Wide Vin, 100mA Integrated Secondary Bias Regulator for Isolated DC/DC Converters LM34926 — 7.5-100V Wide Vin, 300mA Integrated Secondary Bias Regulator for Isolated DC/DC Converters LM34927 — 7.5-100V Wide Vin, 600mA Integrated Secondary Bias Regulator for Isolated DC/DC Converters LM5000 — 3.1-40V Wide Vin, 2A Current Mode Non-Synchronous Boost Regulator LM5001 — 3.1-75V Wide Vin, 1A Current Mode Non-Synchronous Switch Mode Regulator LM5001-Q1 — 3.1-V to 75-V wide VIN, 1-A current mode non-synchronous switch mode regulator LM5002 — 3.1-75V Wide Vin, 0.5A Current Mode Boost, Flyback, Sepic Converter LM5015 — 4.25-75V, Monolithic Two-Switch Forward DC-DC Regulator LM5017 — 7.5-100V Wide Vin, 600mA Constant On-Time Synchronous Buck Regulator LM5018 — 7.5-100V Wide Vin, 300mA Constant On-Time Synchronous Buck Regulator LM5019 — 7.5-100V Wide Vin, 100mA Constant On-Time Synchronous Buck Regulator LM5160 — LM5160 wide input 65V, 2A synchronous buck/Fly-Buck™ converter LM5160-Q1 — Wide Input 65V, 2A Synchronous Buck / Fly-Buck™ Converter LM5160A — LM5160A Wide Input 65V, 2A Synchronous Buck / Fly-Buck™ Converter LM5161 — Wide Input 4.5-V to 100-V, 1-A Synchronous Buck / Fly-Buck Converter LM78S40 — 1.5A Adjustable Step Up, Step Down or Inverting Regulator TPS55340 — 5-A, 40-V, wide VIN boost, flyback, & SEPIC converter TPS55340-EP — Enhanced integrated, 5-A, 40-V wide input range boost/SEPIC/flyback DC/DC regulator TPS55340-Q1 — Integrated, 5-A 40-V wide input range boost/SEPIC/flyback DC/DC regulator, AEC-Q100 qualified TPS61175 — 3-A ,40V High Voltage Boost Converter with Soft-start and Programmable Switching Frequency TPS61175-Q1 — 3-A, 40-V high voltage boost converter with soft-start and programmable switching frequency
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Calculation tool

LM3478-88-BOOST-CALC — LM3478-88 quick start calculator for boost

LM3478-88 quick start calculator for boost topology
Supported products & hardware

Supported products & hardware

Products
AC/DC & DC/DC controllers (external FET)
LM3478 — 2.97~40V Wide Input Range Boost/SEPIC/Flyback DC-DC Controller LM3478Q-Q1 — 40-V wide VIN low-side N-channel controller for switching regulators with 10-µA shutdown current LM3488 — 2.97V to 40V Wide Vin Low-Side N-Channel Controller for Switching Regulators LM3488Q-Q1 — 40-V wide VIN low-side N-channel controller for switching regulators with 5-µA shutdown current
Hardware development
Evaluation board
LM3478EVAL — High Efficiency Low-Side N-Channel Controller for Switching Regulator
Download
Calculation tool

LM3478-88-FLYBACK-CALC — LM3478-88 quick start calculator for Flyback

The LM3478-88 Flyback quick start calculator tool assists in the configuration of the power stage and the external components for the LM3478 and LM3488 devices
Supported products & hardware

Supported products & hardware

Products
AC/DC & DC/DC controllers (external FET)
LM3478 — 2.97~40V Wide Input Range Boost/SEPIC/Flyback DC-DC Controller LM3478Q-Q1 — 40-V wide VIN low-side N-channel controller for switching regulators with 10-µA shutdown current LM3488 — 2.97V to 40V Wide Vin Low-Side N-Channel Controller for Switching Regulators LM3488Q-Q1 — 40-V wide VIN low-side N-channel controller for switching regulators with 5-µA shutdown current
Hardware development
Evaluation board
LM3478EVAL — High Efficiency Low-Side N-Channel Controller for Switching Regulator
Download
Calculation tool

LM3478-88-SEPIC-CALC — LM3478-88 quick start calculator for SEPIC

The LM3478-88 SEPIC quick start calculator tool assists in the configuration of the power stage and the external components for the LM3478 and LM3488.
Supported products & hardware

Supported products & hardware

Products
AC/DC & DC/DC controllers (external FET)
LM3478 — 2.97~40V Wide Input Range Boost/SEPIC/Flyback DC-DC Controller LM3478Q-Q1 — 40-V wide VIN low-side N-channel controller for switching regulators with 10-µA shutdown current LM3488 — 2.97V to 40V Wide Vin Low-Side N-Channel Controller for Switching Regulators LM3488Q-Q1 — 40-V wide VIN low-side N-channel controller for switching regulators with 5-µA shutdown current
Hardware development
Evaluation board
LM3478EVAL — High Efficiency Low-Side N-Channel Controller for Switching Regulator
Download
Reference designs

TIDA-010046 — EMC-compliant 10/100-Mbps Ethernet PHY reference design with IEEE802.3at Type-1 (≤ 12.95 W) PoE-PD

This reference design is optimized for 10 to 100 Mbps using the low-power Ethernet physical layer (PHY) DP83825 supporting 150-m reach over CAT5e cable which is beyond the standard Ethernet distance limitation of 100 m (328 feet). This design has power delivery over Ethernet cable along with data (...)
Design guide: PDF
Schematic: PDF
Reference designs

TIDA-01373 — EEPROM Programming Tool Reference Design

The TIDA-01373 is a reference hardware and software example of a scalable programming tool for the DRV10983, DRV10975, DRV10983-Q1, and DRV10987 integrated BLDC motor drivers. These devices feature configurable EEPROM registers that need to be set to motor-specific parameters. This reference (...)
Design guide: PDF
Schematic: PDF
Reference designs

PMP10077 — High Voltage Ratio Vout/Vin, 2W Boost Converter Reference Design

When high voltage ratio between output and input is required, it's always difficult to choose the right topology. In this case, the most-simple Boost has been selected due to cost reasons. The converter runs in DCM mode therefore avoiding the Trr of the diode and shows good efficiency.
Test report: PDF
Schematic: PDF
Package Pins CAD symbols, footprints & 3D models
SOIC (D) 8 Ultra Librarian
VSSOP (DGK) 8 Ultra Librarian
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Ordering & quality

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  • MTBF/FIT estimates
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  • Ongoing reliability monitoring
Information included:
  • Fab location
  • Assembly location

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