75V Synchronous Buck Controller With Wide Input Voltage and Duty Cycle Ranges


Product details


Vin (Min) (V) 6 Vin (Max) (V) 75 Vout (Min) (V) 0.8 Vout (Max) (V) 60 Iout (Max) (A) 30 Iq (Typ) (uA) 1500 Switching frequency (Min) (kHz) 100 Switching frequency (Max) (kHz) 1000 Features Adjustable Current Limit, Enable, Frequency Synchronization, Light Load Efficiency, Power Good, Pre-Bias Start-Up, Synchronous Rectification, Tracking, UVLO Adjustable Operating temperature range (C) -40 to 125 Regulated outputs (#) 1 Number of phases 1 Rating Catalog open-in-new Find other Buck controllers (external switch)

Package | Pins | Size

VQFN (RGY) 20 16 mm² 4.5 x 3.5 open-in-new Find other Buck controllers (external switch)


  • Versatile synchronous buck DC/DC controller
    • Wide input voltage range of 6 V to 75 V
    • 0.8-V reference with ±1% feedback accuracy
    • Adjustable output voltage from 0.8 V to 60 V
    • 40-ns tON(min) for high VIN / VOUT ratio
    • 140-ns tOFF(min) for low dropout
    • Optimized for CISPR 32 requirements
  • Switching frequency from 100 kHz to 1 MHz
    • SYNC In and SYNC Out capability
    • Selectable diode emulation or FPWM
  • 7.5-V gate drivers for standard VTH MOSFETs
    • 14-ns adaptive dead-time control
    • 2.3-A source and 3.5-A sink capability
    • Low-side soft start for prebiased start-up
  • Fast line and load transient response
    • Voltage-mode control with line feedforward
    • High gain-bandwidth error amplifier
  • Inherent protection features for robust design
    • Adjustable output voltage soft start
    • Hiccup-mode overcurrent protection
    • Input UVLO with hysteresis
    • VCC and gate-drive UVLO protection
    • Precision enable input and open-drain PGOOD indicator for sequencing and control
    • Thermal shutdown protection with hysteresis
  • 20-pin VQFN package with wettable flanks
  • Create a custom design using the LM5145 with WEBENCH Power Designer
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The LM5145 75-V synchronous buck controller regulates from a high input voltage source or from an input rail subject to high voltage transients, minimizing the need for external surge suppression components. A high-side switch minimum on-time of 40 ns gives large step-down ratios, enabling the direct step-down conversion from a 48-V nominal input to low-voltage rails for reduced system complexity and solution cost. The LM5145 continues to operate during input voltage dips as low as 6 V, at nearly 100% duty cycle if needed, making it an excellent choice for high-performance industrial control, robotic, datacom, and RF power applications.

Forced-PWM (FPWM) operation eliminates switching frequency variation to minimize EMI, while user-selectable diode emulation lowers current consumption at light-load conditions. The adjustable switching frequency as high as 1 MHz can be synchronized to an external clock source to eliminate beat frequencies in noise-sensitive applications.

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Technical documentation

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Type Title Date
* Data sheet LM5145 75-V Synchronous Buck DC/DC Controller With Wide Duty Cycle Range datasheet (Rev. B) Nov. 19, 2020
Application note An Accurate Approach for Calculating the Efficiency of a Synchronous Buck Conver Jul. 02, 2020
Application note Wide-Vin Battery-Charger Using SMBus MSP430 MCUs and bq Fuel Gauges (Rev. B) Jul. 12, 2019
White paper Valuing wide VIN, low EMI synchronous buck circuits for cost-driven, demanding a (Rev. A) Apr. 10, 2019
Application note IC Package Features Lead to Higher Reliability in Automotive Systems Feb. 20, 2019
Application note Improving RF Power Amplifier Efficiency in 5G Radio Systems Sep. 05, 2018
User guide LM5146-Q1EVM User's Guide Aug. 10, 2018
Technical article A review of EMI standards, part 2 – radiated emissions Jul. 05, 2018
Technical article A review of EMI standards, part 1 – conducted emissions Jun. 28, 2018
White paper An overview of radiated EMI specifications for power supplies Jun. 05, 2018
Selection guide DC/DC Buck Controller Solutions Selection Guide Feb. 06, 2018
White paper An overview of conducted EMI specifications for power supplies Feb. 01, 2018
Application note Improve DC/DC Regulator EMI for Free with Optimized Power Stage Layout Nov. 13, 2017
Technical article How to design a simple two-phase current-sharing synchronous buck regulator using a voltage-mode controller Nov. 03, 2017
Selection guide Control-Mode Quick Reference Guide (Rev. A) Sep. 14, 2017
Technical article Synchronous buck controller solutions support wide VIN performance and flexibility Jun. 29, 2017
User guide LM5145EVM-HD-20A High Density Evaluation Module (Rev. A) Jun. 07, 2017
Application note Reduce buck-converter EMI and voltage stress by minimizing inductive parasitics Jul. 21, 2016
Application note Power Topology - Buck Converter Aug. 16, 2010
Application note Load-Sharing TPS40050 Modules Using the UCC39002 Load-Share Controller Apr. 13, 2004
Application note Seminar 900 Topic 2 - Snubber Circuits: Theory, Design and Application Feb. 15, 2001

Design & development

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

Hardware development

document-generic User guide
The LM5145EVM-HD-20A high density evaluation module (EVM) is designed to showcase the performance of the LM5145 high performance, synchronous buck DC-DC buck controller with wide input voltage range. The design is packaged in a miniature footprint with low component count. It operates over a wide (...)
  • 24V to 72V input voltage range
  • 5V output voltage, adjustable from 3.3V to 8V
  • Delivers up to 20A of load current
  • Free-running switching frequency of 220kHz, synchronizable to an external clock from -20% to +50%
  • Fully assembled, tested and proven PCB layout with 30-mm x 15-mm total footprint

Design tools & simulation

SNVMB65C.ZIP (150 KB) - PSpice Model
PSpice® for TI design and simulation tool
PSPICE-FOR-TI — PSpice® for TI is a design and simulation environment that helps evaluate functionality of analog circuits. This full-featured, design and simulation suite uses an analog analysis engine from Cadence®. Available at no cost, PSpice for TI includes one of the largest model libraries in the (...)
  • Leverages Cadence PSpice Technology
  • Preinstalled library with a suite of digital models to enable worst-case timing analysis
  • Dynamic updates ensure you have access to most current device models
  • Optimized for simulation speed without loss of accuracy
  • Supports simultaneous analysis of multiple products
  • (...)
LM5145 Synchronous Buck Controller Design Tool
LM5145DESIGN-CALC Welcome to the LM5145 Quickstart Design Tool. This standalone tool facilitates and assists the power supply engineer with the design of a DC/DC buck regulator based on the LM5145 75V synchronous buck controller. As such, the user can expeditiously arrive at an optimized design to meet the (...)
  • Determine output filter inductance and input and output filter capacitances
  • Select components for soft-start, input UVLO, OCP and output voltage setpoint
  • Optimize compensation values and pole/zero placement in terms of control loop stability using crossover frequency as a performance metric
  • Inspect (...)
SNVC206C.ZIP (2389 KB)
SNVR473.ZIP (7838 KB)
SNVR500.ZIP (1493 KB)

Reference designs

57W Output Synchronous Buck Converter for Telecom Reference Design
PMP20178 — PMP20178 is a voltage-mode synchronous buck converter reference design rated for 5.2V output at 11A from an input voltage of 15V to 60V. This design uses the LM5145 synchronous buck controller at a switching frequency of 200 kHz. Features include power good, synchronization and trim functions.
document-generic Schematic document-generic User guide

CAD/CAE symbols

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VQFN (RGY) 20 View options

Ordering & quality

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