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LM5161

ACTIVE

Wide Input 4.5-V to 100-V, 1-A Synchronous Buck / Fly-Buck Converter

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LM5164 ACTIVE 6-V to 100-V input, 1-A synchronous buck DC-DC converter with ultra-low IQ Ultra-low EMI emission.

LM5161

ACTIVE
Data sheet Order now

Product details

Rating Catalog Operating temperature range (°C) -40 to 125 Topology Buck, Flybuck Type Converter Iout (max) (A) 1 Vin (min) (V) 4.5 Vin (max) (V) 100 Switching frequency (min) (kHz) 50 Switching frequency (max) (kHz) 1000 Features Enable, Light load efficiency, Pre-bias soft start, Synchronous rectification Control mode COT with emulated ripple, Constant on-time (COT) Vout (min) (V) 2 Vout (max) (V) 92 Duty cycle (max) (%) 92 Switch current limit (typ) (A) 1.6
Rating Catalog Operating temperature range (°C) -40 to 125 Topology Buck, Flybuck Type Converter Iout (max) (A) 1 Vin (min) (V) 4.5 Vin (max) (V) 100 Switching frequency (min) (kHz) 50 Switching frequency (max) (kHz) 1000 Features Enable, Light load efficiency, Pre-bias soft start, Synchronous rectification Control mode COT with emulated ripple, Constant on-time (COT) Vout (min) (V) 2 Vout (max) (V) 92 Duty cycle (max) (%) 92 Switch current limit (typ) (A) 1.6
HTSSOP (PWP) 14 32 mm² 5 x 6.4
  • Wide 4.5-V to 100-V Input Voltage Range
  • Integrated High-Side and Low-Side Switches
    • No Schottky Diode Required
  • 1-A Maximum Load Current
  • Constant ON-Time Control
    • No External Loop Compensation
    • Fast Transient Response
  • Selectable DCM Buck Operation at Light Load
  • CCM Option Supports Multi-Output Fly-Buck™
  • No External Ripple circuit needed (at FPWM = 0)
  • Nearly Constant Switching Frequency
  • Frequency Adjustable Up to 1 MHz
  • Programmable Soft-Start Time
  • Prebias Start-Up
  • Peak Current Limiting Protection
  • Adjustable Input UVLO and Hysteresis
  • ±1% Feedback Voltage Reference
  • Thermal Shutdown Protection
  • Create a Custom Design Using the LM5161 With the WEBENCH® Power Designer
  • Wide 4.5-V to 100-V Input Voltage Range
  • Integrated High-Side and Low-Side Switches
    • No Schottky Diode Required
  • 1-A Maximum Load Current
  • Constant ON-Time Control
    • No External Loop Compensation
    • Fast Transient Response
  • Selectable DCM Buck Operation at Light Load
  • CCM Option Supports Multi-Output Fly-Buck™
  • No External Ripple circuit needed (at FPWM = 0)
  • Nearly Constant Switching Frequency
  • Frequency Adjustable Up to 1 MHz
  • Programmable Soft-Start Time
  • Prebias Start-Up
  • Peak Current Limiting Protection
  • Adjustable Input UVLO and Hysteresis
  • ±1% Feedback Voltage Reference
  • Thermal Shutdown Protection
  • Create a Custom Design Using the LM5161 With the WEBENCH® Power Designer

The LM5161 is a 100-V, 1-A synchronous step-down converter with integrated high-side and low-side MOSFETs. The constant-ON-time control scheme requires no loop compensation and supports high step-down ratios with fast transient response. An internal feedback amplifier maintains ±1% output voltage regulation over the entire operating temperature range. The ON-time varies inversely with input voltage resulting in nearly constant switching frequency. Peak and valley current limit circuits protect against overload conditions. The under-voltage lockout (EN/UVLO) circuit provides independently adjustable input undervoltage threshold and hysteresis. The FPWM input pin in LM5161 selects either the forced continuous conduction mode (CCM) under all load levels or the discontinuous conduction mode (DCM) under light or no load conditions. When operating in forced CCM, the LM5161 supports the multiple output and isolated Fly-Buck applications. When programmed for the DCM operation, the LM5161 provides a tightly regulated buck output without any additional external feedback ripple injection circuit.

The LM5161 is a 100-V, 1-A synchronous step-down converter with integrated high-side and low-side MOSFETs. The constant-ON-time control scheme requires no loop compensation and supports high step-down ratios with fast transient response. An internal feedback amplifier maintains ±1% output voltage regulation over the entire operating temperature range. The ON-time varies inversely with input voltage resulting in nearly constant switching frequency. Peak and valley current limit circuits protect against overload conditions. The under-voltage lockout (EN/UVLO) circuit provides independently adjustable input undervoltage threshold and hysteresis. The FPWM input pin in LM5161 selects either the forced continuous conduction mode (CCM) under all load levels or the discontinuous conduction mode (DCM) under light or no load conditions. When operating in forced CCM, the LM5161 supports the multiple output and isolated Fly-Buck applications. When programmed for the DCM operation, the LM5161 provides a tightly regulated buck output without any additional external feedback ripple injection circuit.
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Technical documentation

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Type Title Date
* Data sheet LM5161 Wide Input 100-V, 1-A Synchronous Buck/Fly-Buck™ Converter datasheet (Rev. B) PDF | HTML 27 Nov 2017
Product overview Isolated Power Topologies for PLC I/O Modules and Other Low-Power Applications (Rev. A) PDF | HTML 20 Aug 2024
Application note Step-Dwn (Buck) Convrtr Pwer Solutions for Programmable Logic Controller Systems (Rev. A) PDF | HTML 26 Jul 2021
Selection guide Buck Converter Quick Reference Guide (Rev. B) 08 Apr 2021
White paper Valuing wide VIN, low EMI synchronous buck circuits for cost-driven, demanding a (Rev. A) 10 Apr 2019
Application note Stability Analysis and Design of COT Type-3 Ripple Circuit 20 Mar 2019
Application brief Powering Drones With a Wide VIN DC-DC Converter (Rev. A) 05 Feb 2019
Technical article Why a wide VIN DC/DC converter is a good fit for high-cell-count battery-powered d PDF | HTML 21 Nov 2017
Technical article Simplifying 100V wide VIN power conversion PDF | HTML 11 Nov 2016
EVM User's guide LM5161 Fly-Buck (Isolated Buck) EVM User’s Guide (Rev. A) 19 Aug 2016
EVM User's guide LM5161PWPBKEVM Buck Evaluation Module User's Guide (Rev. A) 19 Aug 2016
Technical article Create a Fly-Buck™ converter in WEBENCH® Power Designer PDF | HTML 09 Oct 2015
White paper Designing isolated rails on the fly with Fly-Buck™ converters 29 Sep 2015
Technical article How to design for EMC and isolation with Fly-Buck™ converters PDF | HTML 28 Jul 2015
Application note Is Your IGBT Gate-Driver Power Supply Optimized 12 Mar 2015
Analog Design Journal Fly-Buck(TM) converter provides EMC and isolation in PLC applications 29 Jan 2015
Application note AN-2292 Designing an Isolated Buck (Fly-Buck) Converter (Rev. C) 17 Dec 2014
White paper Wide VIN power management ICs simplify white paper (Rev. A) 19 Sep 2013
Application note AN-2218 Precision Current Limiting with the LMP8646 and LM3102 (Rev. A) 23 Apr 2013

Design & development

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

Evaluation board

LM5161PWPBKEVM — LM5161 Wide VIN Synchronous Buck Converter Constant On-Time Evaluation Module

The LM5161PWPBKEVM evaluation board provides a fully functional buck regulator, employing the constant on-time (COT) operating principle. This evaluation board provides a 12-V output over an input range of 15V to 80 V. The circuit delivers load currents to 1.0 A. The application schematic is setup (...)
User guide: PDF
Not available on TI.com
Evaluation board

LM5161PWPFBKEVM — LM5161 Wide VIN Fly-Buck Evaluation Module

The LM5161PWPFBKEVM evaluation board provides a fully functional Fly-buck regulator, employing the constant on-time (COT) operating principle. This evaluation board provides a 12-V secondary isolated output voltage over an input range of 36V to 72 V. The circuit delivers secondary output load (...)
User guide: PDF
Not available on TI.com
Simulation model

LM5161 PSpice Buck and Fly-Buck Transient Model

SNVMAV3.ZIP (499 KB) - PSpice Model
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Simulation model

LM5161 Unencrypted PSpice Buck and Fly-Buck Transient Model

SNVMAV4.ZIP (3 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

SNVC199 — LM5161 Buck Quick Start Component Selector

Supported products & hardware

Supported products & hardware

Products
AC/DC & DC/DC converters (integrated FET)
LM5161 — Wide Input 4.5-V to 100-V, 1-A Synchronous Buck / Fly-Buck Converter
Download
Calculation tool

SNVC200 — LM5161 Fly-Buck Quick Start Component Selector

Supported products & hardware

Supported products & hardware

Products
AC/DC & DC/DC converters (integrated FET)
LM5161 — Wide Input 4.5-V to 100-V, 1-A Synchronous Buck / Fly-Buck Converter
Download
Reference designs

PMP23332 — Interleaved and multiphase inverting buck-boost converter reference design

This reference design uses the UCD3138064A as a digital controller to control inverting buck-boost with the capability of supporting two-phase peak current mode control. The soft-switching technology is used in this design to improve the power efficiency. The input voltage range is -62 V to -36 V. (...)
Test report: PDF
Reference designs

PMP20587 — Inverting buck-boost reference design

This reference design uses UCD3138064A as a digital controller to control two-phase two-rail inverting buck-boost. This non-isolated converter is used for wireless radio power. The input voltage is from -35 V to -60 V. There are two outputs. The default output voltage of rail 1 is 32 V and max (...)
Test report: PDF
Schematic: PDF
Reference designs

PMP4486 — 48Vin Digital POL with 3 Outputs Reference Design

The PMP4486 is a GaN-based reference design solution for telecom and computing applications. The GaN module LMG5200 enables a high efficiency single stage conversion with an input range from 36 to 60V down to 29V, 12V and 1.0V. This design shows the benefits of a GaN based design with high (...)
Test report: PDF
Schematic: PDF
Reference designs

PMP40042 — Flybuck For 48Vin Isolated System Aux. Power Reference Design

The PMP40042 is a D-CAP Aux. isolated power supply reference design solution for the Telecom & Server applications. High integration and low switching loss, with the UVLO, OTP, OCP, SS and Prebias Start-up, the module enables a high efficiency for 48V system application.  A low cost & (...)
Test report: PDF
Schematic: PDF
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HTSSOP (PWP) 14 Ultra Librarian
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