LM25145

ACTIVE

6V to 42V Synchronous Buck DC-DC Controller With Wide Duty Cycle Range

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Product details

Parameters

Vin (Min) (V) 6 Vin (Max) (V) 42 Vout (Min) (V) 0.8 Vout (Max) (V) 40 Iout (Max) (A) 30 Iq (Typ) (mA) 1.8 Iq (Typ) (uA) 1800 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)

Features

  • Versatile Synchronous Buck DC-DC Controller
    • Wide Input Voltage Range of 6 V to 42 V
    • Adjustable Output Voltage From 0.8 V to 40 V
  • Meets EN55022 / CISPR 22 EMI Standards
  • Lossless RDS(on) or Shunt Current Sensing
  • Switching Frequency From 100 kHz to 1 MHz
    • SYNC In and SYNC Out Capability
  • 40-ns Minimum On-Time for High VIN / VOUT Ratio
  • 140-ns Minimum Off-Time for Low Dropout
  • 0.8-V Reference With ±1% Feedback Accuracy
  • 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
  • Adjustable Soft-Start or Optional Voltage Tracking
  • Fast Line and Load Transient Response
    • Voltage-Mode Control With Line Feedforward
    • High Gain-Bandwidth Error Amplifier
  • Precision Enable Input and Open-Drain Power Good Indicator for Sequencing and Control
  • Inherent Protection Features for Robust Design
    • Hiccup Mode Overcurrent Protection
    • Input UVLO With Hysteresis
    • VCC and Gate Drive UVLO Protection
    • Thermal Shutdown Protection With Hysteresis
  • VQFN-20 Package With Wettable Flanks
  • Create a Custom Design Using the LM25145 With WEBENCH® Power Designer

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Description

The LM25145 42-V synchronous buck controller is designed to regulate 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 facilitates large step-down ratios, enabling the direct step-down conversion from a 24 V nominal input to low-voltage rails for reduced system complexity and solution cost. The LM25145 continues to operate during input voltage dips as low as 6 V, at nearly 100% duty cycle if needed, making it well suited for high-performance industrial control, robotic, datacom, and RF power amplifier applications.

Forced-PWM (FPWM) operation eliminates frequency variation to minimize EMI, while a user-selectable diode emulation feature lowers current consumption at light-load conditions. Cycle-by-cycle overcurrent protection is accomplished by measuring the voltage drop across the low-side MOSFET or by using an optional current sense resistor. 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.

The LM25145 voltage-mode controller drives external high-side and low-side N-channel power switches with robust 7.5-V gate drivers suitable for standard-threshold MOSFETs. Adaptively-timed gate drivers with 2.3-A source and 3.5-A sink capability minimize body diode conduction during switching transitions, reducing switching losses and improving thermal performance when driving MOSFETs at high input voltage and high frequency. The LM25145 can be powered from the output of the switching regulator or another available source, further improving efficiency.

A 180° out-of-phase clock output relative to the internal oscillator at SYNCOUT is ideal for cascaded or multi-channel power supplies to reduce input capacitor ripple current and EMI filter size. Additional features of the LM25145 include a configurable soft-start, an open-drain Power Good monitor for fault reporting and output monitoring, monotonic start-up into prebiased loads, integrated VCC bias supply regulator and bootstrap diode, external power supply tracking, precision enable input with hysteresis for adjustable line undervoltage lockout (UVLO), hiccup-mode overload protection, and thermal shutdown protection with automatic recovery.

The LM25145 controller is offered in a 3.5-mm × 4.5-mm thermally-enhanced, 20-pin VQFN package with additional spacing for high-voltage pins and wettable flanks for optical inspection of solder joint fillets.

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Technical documentation

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Type Title Date
* Datasheet LM25145 6-V to 42-V Synchronous Buck DC-DC Controller With Wide Duty Cycle Range datasheet Jun. 22, 2017
Selection guides Buck Converter Quick Reference Guide (Rev. A) Mar. 31, 2020
White papers Valuing wide VIN, low EMI synchronous buck circuits for cost-driven, demanding a (Rev. A) Apr. 10, 2019
Application notes Improving RF Power Amplifier Efficiency in 5G Radio Systems Sep. 05, 2018
User guides LM5146-Q1EVM User's Guide Aug. 10, 2018
Technical articles A review of EMI standards, part 2 – radiated emissions Jul. 05, 2018
Technical articles A review of EMI standards, part 1 – conducted emissions Jun. 28, 2018
White papers An overview of radiated EMI specifications for power supplies Jun. 05, 2018
Selection guides DC/DC Buck Controller Solutions Selection Guide Feb. 06, 2018
White papers An overview of conducted EMI specifications for power supplies Feb. 01, 2018
Application notes Improve DC/DC Regulator EMI for Free with Optimized Power Stage Layout Nov. 13, 2017
Selection guides Control-Mode Quick Reference Guide (Rev. A) Sep. 14, 2017
Technical articles Synchronous buck controller solutions support wide VIN performance and flexibility Jun. 29, 2017
User guides LM5145EVM-HD-20A High Density Evaluation Module (Rev. A) Jun. 07, 2017
Application notes Reduce buck-converter EMI and voltage stress by minimizing inductive parasitics Jul. 21, 2016
Technical articles High Density PCB Layout of DC/DC Converters, Part 2 Sep. 16, 2015

Design & development

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

Hardware development

EVALUATION BOARDS Download
document-generic User guide
99
Description
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 (...)
Features
  • 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

SIMULATION MODELS Download
SNVMBB9A.ZIP (125 KB) - PSpice Model
SIMULATION TOOLS Download
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 (...)
Features
  • 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
  • (...)
CALCULATION TOOLS Download
LM25145 Synchronous Buck Controller Design Tool
LM25145DESIGN-CALC Welcome to the LM25145 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 LM25145 42V synchronous buck controller. As such, the user can expeditiously arrive at an optimized design to meet the (...)
Features
  • 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 (...)
CALCULATION TOOLS Download
SNVC207C.ZIP (2393 KB)
PCB LAYOUTS Download
SNVR473.ZIP (7838 KB)

CAD/CAE symbols

Package Pins Download
VQFN (RGY) 20 View options

Ordering & quality

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