3.5-V to 65-V low Iq, dual, 2-phase synchronous buck DC-DC controller


Product details


Vin (Min) (V) 3.5 Vin (Max) (V) 65 Vout (Min) (V) 0.6 Vout (Max) (V) 55 Iout (Max) (A) 100 Iq (Typ) (uA) 15 Switching frequency (Min) (kHz) 100 Switching frequency (Max) (kHz) 2200 Features Adjustable Current Limit, Enable, Frequency Synchronization, Light Load Efficiency, Multiple Outputs, Phase Interleaving, Power Good, Pre-Bias Start-Up, Spread Spectrum, Synchronous Rectification, Tracking, UVLO Fixed Operating temperature range (C) -40 to 150 Regulated outputs (#) 2 TI functional safety category Functional Safety-Capable Number of Phases 2 Rating Automotive open-in-new Find other Buck controllers (external switch)

Package | Pins | Size

VQFNP (RWG) 40 36 mm² 6 x 6 open-in-new Find other Buck controllers (external switch)


  • AEC-Q100 qualified for automotive applications:
    • Device temperature grade 1: –40°C to +125°C ambient operating temperature
  • Versatile synchronous buck DC/DC controller
    • Wide input voltage range of 3.5 V to 65 V
    • 1% accurate, fixed 3.3-V, 5-V or adjustable outputs from 0.6 V to 55 V
    • 150°C maximum junction temperature
    • Shutdown mode current: 4 µA typical
    • No-load standby current: 15 µA typical
  • Two interleaved synchronous buck channels
    • Dual-channel or single-output multiphase
    • 65-ns tON(min) for high VIN/VOUT ratio
    • 60-ns tOFF(min) for low dropout
  • Switching frequency from 100 kHz to 2.2 MHz
    • SYNC in and SYNC out capability
  • Inherent protection features for robust design
    • Hiccup-mode overcurrent protection
    • Independent ENABLE and PGOOD functions
    • VCC, VDDA, and gate-drive UVLO protection
    • Thermal shutdown protection with hysteresis
  • Optimized for ultra-low EMI requirements
    • Slew-rate controlled adaptive gate drivers
    • Spread spectrum reduces peak emissions
    • Meets CISPR 25 Class 5 standard
  • VQFNP-40 package with wettable flank pins
  • Create a custom design using the LM5143-Q1 with WEBENCH® Power Designer

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The LM5143-Q1 is a 65-V synchronous buck DC/DC controller for high-current single or dual outputs. The device uses an interleaved, stackable, peak current-mode control architecture for easy loop compensation, fast transient response, excellent load and line regulation, and accurate current sharing with paralleled phases for higher output current. A high-side switch minimum on-time of 65 ns gives large step-down ratios, enabling the direct conversion from 12-V, 24-V or 48-V automotive inputs to low-voltage rails for reduced system complexity and solution cost. The LM5143-Q1 continues to operate during input voltage dips as low as 3.5 V, at nearly 100% duty cycle if needed.

Current is sensed using the inductor DCR for highest efficiency or an optional shunt resistor for high accuracy. The 15-µA no-load quiescent current with the output voltage in regulation extends operating run-time in battery-powered systems. Power the LM5143-Q1 from the output of the switching regulator or another available source for even lower input quiescent current and power loss.

Several features are included to simplify compliance with CISPR 25 and automotive EMI requirements. Adaptively timed, high-current MOSFET gate drivers with adjustable slew rate control minimize body diode conduction during switching transitions, reducing switching losses and improving thermal and EMI performance at high input voltage and high switching frequency. To reduce input capacitor ripple current and EMI filter size, 180° interleaved operation is provided for two outputs. A 90° out-of-phase clock output works well for cascaded, multi-channel, or multi-phase power stages. Resistor-adjustable switching frequency as high as 2.2 MHz can be synchronized to an external clock source up to 2.5 MHz to eliminate beat frequencies in noise-sensitive applications. Optional triangular spread spectrum modulation further improves the EMI signature.

Additional features of the LM5143-Q1 include 150°C maximum junction temperature operation, user-selectable diode emulation for lower current consumption at light-load conditions, configurable soft-start functions, open-drain Power-Good flags for fault reporting and output monitoring, independent enable inputs, monotonic start-up into prebiased loads, integrated VCC bias supply regulator, programmable hiccup-mode overload protection, and thermal shutdown protection with automatic recovery.

The LM5143-Q1 controller comes in a 6-mm × 6-mm thermally-enhanced, 40-pin VQFNP package with wettable flank pins to facilitate optical inspection during manufacturing.

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Technical documentation

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Type Title Date
* Datasheet LM5143-Q1 3.5-V to 65-V Low IQ, Dual Synchronous Buck DC/DC Controller datasheet (Rev. B) Oct. 17, 2019
Selection guide Buck Converter Quick Reference Guide (Rev. B) Apr. 08, 2021
Technical article Powering levels of autonomy: a quick guide to DC/DC solutions for SAE autonomy levels Nov. 18, 2020
White paper Streamlining Functional Safety Certification in Automotive and Industrial Jun. 09, 2020
White paper 簡化汽車及工業領域的功 能安全認證 Jun. 09, 2020
White paper 자동차 및 산업 분야의 기능적 안전성 인증 간소화 Jun. 09, 2020
Application note LM5143-Q1 4-phase Buck Regulator Design (Rev. A) Apr. 28, 2020
User guide LM5143-Q1 EVM User's Guide (Rev. B) Apr. 16, 2020
Functional safety information LM5143-Q1 Functional Safety FIT Rate and Failure Mode Distribution Dec. 23, 2019
Technical article Powering infotainment systems of the future Oct. 07, 2019
Application note LM5143-Q1 4-phase buck regulator design Mar. 01, 2019
Application note IC Package Features Lead to Higher Reliability in Automotive Systems Feb. 20, 2019
Technical article Searching for the newest innovations in power? Find them at APEC Feb. 09, 2019
Selection guide Automotive Infotainment EE Buck Converter/Controller Selection Guide (Rev. A) Jan. 15, 2019
White paper An overview of radiated EMI specifications for power supplies Jun. 05, 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

Design & development

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Hardware development

document-generic User guide
The LM5143-Q1-EVM2100 high density evaluation module (EVM) is designed to showcase the performance of the LM5143-Q1 high performance, dual-channel, automotive synchronous buck DC/DC buck controller. It operates over a wide input voltage range of 3.5 V to 36 V to deliver fixed 5-V and 3.3-V outputs (...)
  • 3.5-V to 36-V input voltage range
  • 5-V and 3.3-V output voltages with 1% setpoint accuracy
  • Rated for up to 7 A of load current per channel
  • Automotive grade power stage components, including MOSFETs, inductors and capacitors
  • 2.1-MHz switching synchronizable up or down with external clock
  • Fully assembled (...)

Design tools & simulation

SNVMBN0.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
  • (...)
LM5143-Q1 controller quickstart design tool
LM5143DESIGN-CALC — Welcome to the LM5143-Q1 Quickstart Design Tool. This standalone tool facilitates and assists the power supply engineer with design of a DC/DC buck regulator based on the LM5143-Q1 65-V synchronous buck DC/DC controller with low IQ. As such, the user can expeditiously arrive at an optimized design (...)
  • Configure the controller for dual-output, two-phase or multi-phase configurations.
  • Determine buck inductance and input and output capacitances
  • Select components for soft-start, hiccup-mode restart, OCP, switching frequency and output voltage setpoint(s)
  • Optimize compensation values and pole/zero (...)
SNVC229E.ZIP (2085 KB)
SNVR474.ZIP (2613 KB)

Reference designs

Automotive wide VIN front-end reference design for digital cockpit processing units
PMP30670 — This reference design shows a complete power tree for automotive digital cockpit applications. The LM74700-Q1 provides low-loss reverse polarity protection to the system, followed by an input filter. The LM5143-Q1 dual-synchronous buck converter provides a 3.3-V rail, which can support up to 15 A (...)
document-generic Schematic document-generic User guide

CAD/CAE symbols

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