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LM34926

ACTIVE

7.5-100V Wide Vin, 300mA Integrated Secondary Bias Regulator for Isolated DC/DC Converters

A newer version of this product is available

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LM5168 ACTIVE 6-V to 120-V wide VIN, 300-mA DC-DC converter with Fly-Buck™ capability 120-V rating and lower IQ.

Product details

Device type Converters Topology Buck, Flybuck Vin (min) (V) 9 Vin (max) (V) 100 Vout (min) (V) 1.25 Vout (max) (V) 90 Iout (max) (A) 0.3 Features Enable, UVLO adjustable Operating temperature range (°C) -40 to 125 Regulated outputs (#) 1 Control mode Constant on-time (COT) Rating Catalog
Device type Converters Topology Buck, Flybuck Vin (min) (V) 9 Vin (max) (V) 100 Vout (min) (V) 1.25 Vout (max) (V) 90 Iout (max) (A) 0.3 Features Enable, UVLO adjustable Operating temperature range (°C) -40 to 125 Regulated outputs (#) 1 Control mode Constant on-time (COT) Rating Catalog
HSOIC (DDA) 8 29.4 mm² 4.9 x 6 WSON (NGU) 8 16 mm² 4 x 4
  • Wide 7.5-V to 100-V Input Range
  • Integrated 300-mA High-Side
    and Low-Side Switches
  • No Schottky Required
  • Constant On-Time Control
  • No Loop Compensation Required
  • Ultra-Fast Transient Response
  • Nearly Constant Operating Frequency
  • Intelligent Peak Current Limit
  • Adjustable Output Voltage From 1.225 V
  • Precision 2% Feedback Reference
  • Frequency Adjustable to 1 MHz
  • Adjustable Undervoltage Lockout (UVLO)
  • Remote Shutdown
  • Thermal Shutdown
  • Packages:
    • WSON-8
    • SO PowerPAD™-8 Packages
  • Create a Custom Design Using the LM34926 With the WEBENCH® Power Designer
  • Wide 7.5-V to 100-V Input Range
  • Integrated 300-mA High-Side
    and Low-Side Switches
  • No Schottky Required
  • Constant On-Time Control
  • No Loop Compensation Required
  • Ultra-Fast Transient Response
  • Nearly Constant Operating Frequency
  • Intelligent Peak Current Limit
  • Adjustable Output Voltage From 1.225 V
  • Precision 2% Feedback Reference
  • Frequency Adjustable to 1 MHz
  • Adjustable Undervoltage Lockout (UVLO)
  • Remote Shutdown
  • Thermal Shutdown
  • Packages:
    • WSON-8
    • SO PowerPAD™-8 Packages
  • Create a Custom Design Using the LM34926 With the WEBENCH® Power Designer

The LM34926 regulator features all of the functions needed to implement a low-cost, efficient, isolated bias regulator. This high-voltage regulator contains two 100-V N-channel MOSFET switches — a high-side buck switch and a low-side synchronous switch. The constant on-time (COT) control scheme employed in the LM34926 requires no loop compensation and provides excellent transient response. The regulator operates with an on-time control that is inversely proportional to the input voltage. This feature allows the operating frequency to remain relatively constant. An intelligent peak current limit is implemented with integrated sense circuit. Other features include a programmable input undervoltage comparator to inhibit operation during low-voltage conditions. Protection features include thermal shutdown and VCC Undervoltage Lockout (UVLO). The LM34926 device is offered in WSON-8 and SO PowerPAD-8 plastic packages.

The LM34926 regulator features all of the functions needed to implement a low-cost, efficient, isolated bias regulator. This high-voltage regulator contains two 100-V N-channel MOSFET switches — a high-side buck switch and a low-side synchronous switch. The constant on-time (COT) control scheme employed in the LM34926 requires no loop compensation and provides excellent transient response. The regulator operates with an on-time control that is inversely proportional to the input voltage. This feature allows the operating frequency to remain relatively constant. An intelligent peak current limit is implemented with integrated sense circuit. Other features include a programmable input undervoltage comparator to inhibit operation during low-voltage conditions. Protection features include thermal shutdown and VCC Undervoltage Lockout (UVLO). The LM34926 device is offered in WSON-8 and SO PowerPAD-8 plastic packages.

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Technical documentation

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Type Title Date
* Data sheet LM34926 Integrated Secondary-Side Bias Regulator for Isolated DC-DC Converters datasheet (Rev. F) PDF | HTML 30 Nov 2017
Selection guide Power Management Guide 2018 (Rev. R) 25 Jun 2018
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
User guide AN-2204 LM5017 Isolated Supply Evaluation Board (Rev. B) 13 Aug 2013
User guide LM34926 Isolated Evaluation Board (Rev. A) 25 Apr 2013

Design & development

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

Evaluation board

LM34926EVAL — Evaluation Board for the LM34926

An isolated bias supply is implemented in this evaluation board with LM34926 Constant-On-Time regulator. LM34926 regulator integrates both the high and low side power switch- es essential for creating isolated buck converter.

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

LM34926 PSpice Transient Model

SNVM307.ZIP (40 KB) - PSpice Model
Simulation model

LM34926 TINA-TI Reference Design

SNVM363.TSC (679 KB) - TINA-TI Reference Design
Simulation model

LM34926 TINA-TI Transient Spice Model

SNVM364.ZIP (10 KB) - TINA-TI Spice Model
Simulation model

LM34926 Unencrypted PSpice Transient Model

SNVM981.ZIP (2 KB) - PSpice Model
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
Boost converters (integrated switch)
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 LM3578A 2-V to 40-VIN switching regulators in buck, boost, terminal, depending upon the application 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 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
Buck converters (integrated switch)
LM5015 4.25-75V, Monolithic Two-Switch Forward DC-DC Regulator
Isolated DC/DC converters & modules
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 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 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 TPS55010 2.95V To 6V Input, 2W, Isolated DC/DC Converter with Integrated FETS
Boost controllers (external switch)
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 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 UC2572 Negative output Flyback pulse width modulator
PWM controllers
LM3524D 40V, 0.2A 350KHz PWM controller
Reference designs

PMP7798 — Low-Power Isolated Supply, Input range: 36V to 75V, Output: 10V @ 120mA, LM5017

Based on the Wide VIN COT Sync Buck regulator LM5017, this FlyBuck circuit provides excellent regulation for two isolated outputs and one non-isolated output. Compared with a conventional Flyback circuit, this design features a smaller board size and minimized BOM without the need for an (...)
Test report: PDF
Schematic: PDF
Package Pins Download
HSOIC (DDA) 8 View options
WSON (NGU) 8 View options

Ordering & quality

Information included:
  • RoHS
  • REACH
  • Device marking
  • Lead finish/Ball material
  • MSL rating/Peak reflow
  • MTBF/FIT estimates
  • Material content
  • Qualification summary
  • Ongoing reliability monitoring
Information included:
  • Fab location
  • Assembly location

Recommended products may have parameters, evaluation modules or reference designs related to this TI product.

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