7.5-100V Wide Vin, 600mA Integrated Secondary Bias Regulator for Isolated DC/DC Converters


Product details


Vin (Min) (V) 9 Vin (Max) (V) 100 Switching frequency (Max) (kHz) 1000 Soft start Adjustable Features Adjustable UVLO, Enable Operating temperature range (C) -40 to 125 Iout (A) 0.6 Product type Converter (Integrated switch) Topology Flybuck open-in-new Find other Flybuck converters

Package | Pins | Size

HSOIC (DDA) 8 19 mm² 4.9 x 3.9 WSON (NGU) 8 16 mm² 4 x 4 open-in-new Find other Flybuck converters


  • Wide 7.5-V to 100-V Input Range
  • Integrated 600-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:
    • 8-pin WSON
    • 8-pin SO PowerPAD™

All trademarks are the property of their respective owners.

open-in-new Find other Flybuck converters


The LM34927 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 LM34927 device requires no loop compensation and provides excellent transient response. The regulator operates with an on-time 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 LM34927 device is offered in WSON-8 and SO PowerPAD-8 plastic packages.

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Technical documentation

= Top documentation for this product selected by TI
No results found. Please clear your search and try again. View all 7
Type Title Date
* Datasheet LM34927 Integrated Secondary-Side Bias Regulator for Isolated DC-DC Converters datasheet (Rev. H) Nov. 27, 2017
Selection guide Power Management Guide 2018 (Rev. R) Jun. 25, 2018
Application note Fly-Buck(TM) converter provides EMC and isolation in PLC applications Jan. 29, 2015
Application note AN-2292 Designing an Isolated Buck (Fly-Buck) Converter (Rev. C) Dec. 17, 2014
Technical articles Powering Bipolar Rails with Wide-VIN Fly-Buck Converter Dec. 09, 2014
User guide AN-2204 LM5017 Isolated Supply Evaluation Board (Rev. B) Aug. 13, 2013
Application note AN-2202 LM34927 Integrated Bias Regulator for Isolated DC Convtr (Rev. A) Apr. 23, 2013

Design & development

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

Hardware development


The LM34927 regulator features all of the functions needed to implement a low cost, efficient, isolated bias regulator. This high voltage regulator contains two 100V N-Channel MOSFET switches - a high-side buck switch and a low-side synchronous switch. The Constant-on-time (COT) control scheme (...)

Design tools & simulation

SNVM165A.ZIP (39 KB) - PSpice Model
SNVM343.TSC (194 KB) - TINA-TI Reference Design
SNVM344.ZIP (10 KB) - TINA-TI Spice Model
SNVM982.ZIP (2 KB) - PSpice Model
Fly-Buck and Flyback Topology Selector
FLYBUCK-FLYBACK-DESIGN-CALC 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.
  • Features isolated topologies like Fly-Buck™, Fly-Buck-Boost, DCM and CCM Flyback
  • Capability to design up to 6 isolated outputs
  • Recommends ICs for desired application design
  • Incorporates loop compensation in designs
  • Compares efficiency, external component count and transformer currents for every topology (...)

Reference designs

1kW Triple-Rail Isolated DC/DC Digital Power Supply for Telecom (-8V@.25A)
PMP4333 — This reference design demostrates full-function 1.2KW triple-rail digital power supply solution for telecom application. The input range is 36-60Vin and outputs are two 48V10A(Full bridge) and one 5.5V30A(active clamp). Synchrounous rectifiers are used in the design and the overall efficiency is up (...)
48Vin, 300W 1/8brick Digital Module with GaN FET Reference Design
PMP4435 The PMP4435 is a DC-DC isolated digital module with GaN mosfet reference design targeted for industrial and telecom applications. The DC input range is 36V-60V, with 12V typical and the output is 12V/5A. An digital controller UCD3138A is used in the design. The efficiency is up to 95.8% with good (...)
document-generic Schematic document-generic User guide
Low-Power Isolated Supply, Input range: 36V to 75V, Output: 10V @ 120mA, LM5017
PMP7798 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 (...)
document-generic Schematic document-generic User guide
EMI Optimized Layout Design for Fly-buck Reference Design
PMP11052 This reference design (PMP11052) demonstrates the improvement in EMI performance in a Fly-buck design with optimized layout for all high di/dt loops and compares it with another layout which is laid out just like a buck converter.
document-generic Schematic document-generic User guide
600W Half Brick DC/DC Converter with Digital Control for Telecom Applications Reference Design
PMP4320A The PMP4320A reference design is a single output DC-DC converter with standard half-brick dimensions and full digital control configuration based on the UCD3138.  It is capable of delivering 50A output current with an output voltage of 12V.  The converter provides high efficiency and good (...)
document-generic Schematic document-generic User guide

CAD/CAE symbols

Package Pins Download
SO PowerPAD (DDA) 8 View options
WSON (NGU) 8 View options

Ordering & quality

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  • MSL rating/Peak reflow
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  • Qualification summary
  • Ongoing reliability monitoring

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