4.5-36V, Current Mode Dual Synchronous Buck Controller with Oscillator Synchronization


Product details


Vin (Min) (V) 4.5 Vin (Max) (V) 36 Vout (Min) (V) 1.236 Vout (Max) (V) 34 Iout (Max) (A) 20 Iq (Typ) (mA) 1.1 Iq (Typ) (uA) 1100 Switching frequency (Min) (kHz) 150 Switching frequency (Max) (kHz) 250 Features Adjustable Current Limit, Enable, Frequency Synchronization, Synchronous Rectification Operating temperature range (C) -40 to 125 Regulated outputs (#) 2 Number of Phases 2 Rating Catalog open-in-new Find other Buck controllers (external switch)

Package | Pins | Size

HTSSOP (PWP) 28 43 mm² 9.7 x 4.4 TSSOP (PW) 28 62 mm² 9.7 x 6.4 open-in-new Find other Buck controllers (external switch)


  • Two Synchronous Buck Regulators
  • 180° Out of Phase Operation
  • 200 kHz Fixed Nominal Frequency: LM5642
  • 375 kHz Fixed Nominal Frequency: LM5642X
  • Synchronizable Switching Frequency from 150 kHz to 250 kHz for the LM5642 and 200 kHz to 500 kHz for the LM5642X
  • 4.5V to 36V Input Range
  • 50 µA Shutdown Current
  • Adjustable Output from 1.3V to 90% of Vin
  • 0.04% (Typical) Line and Load Regulation Accuracy
  • Current Mode Control with or without a Sense Resistor
  • Independent Enable/Soft-start Pins Allow Simple Sequential Startup Configuration.
  • Configurable for Single Output Parallel Operation.
  • Adjustable Cycle-by-cycle Current Limit
  • Input Under-voltage Lockout
  • Output Over-voltage Latch Protection
  • Output Under-voltage Protection with Delay
  • Thermal Shutdown
  • Self Discharge of Output Capacitors when the Regulator is OFF
  • TSSOP and HTSSOP (Exposed PAD) Packages

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The LM5642 series consists of two current mode synchronous buck regulator controllers operating 180° out of phase with each other at a normal switching frequency of 200kHz for the LM5642 and at 375kHz for the LM5642X.

Out of phase operation reduces the input RMS ripple current, thereby significantly reducing the required input capacitance. The switching frequency can be synchronized to an external clock between 150 kHz and 250 kHz for the LM5642 and between 200 kHz and 500 kHz for the LM5642X. The two switching regulator outputs can also be paralleled to operate as a dual-phase, single output regulator.

The output of each channel can be independently adjusted from 1.3V to 90% of Vin. An internal 5V rail is also available externally for driving bootstrap circuitry.

Current-mode feedback control assures excellent line and load regulation and wide loop bandwidth for excellent response to fast load transients. Current is sensed across either the Vds of the top FET or across an external current-sense resistor connected in series with the drain of the top FET.

The LM5642 features analog soft-start circuitry that is independent of the output load and output capacitance making the soft-start behavior more predictable and controllable than traditional soft-start circuits.

Over-voltage protection is available for both outputs. A UV-Delay pin is also available to allow delayed shut off time for the IC during an output under-voltage event.

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Technical documentation

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No results found. Please clear your search and try again. View all 5
Type Title Date
* Datasheet LM5642/42X High V, Dual Sync Buck Converter w/Oscil Sync datasheet (Rev. K) Apr. 04, 2013
Selection guides Power Management Guide 2018 (Rev. R) Jun. 25, 2018
Application notes Reduce buck-converter EMI and voltage stress by minimizing inductive parasitics Jul. 21, 2016
User guides AN-1292 LM5642 Evaluation Board (Rev. B) Apr. 25, 2013
Application notes Power Management Considerations for FPGAs and ASICs Mar. 22, 2007

Design & development

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Hardware development

document-generic User guide

High Voltage, Dual Synchronous Buck Converter with Oscillator Synchronization

  • Two synchronous buck regulators
  • 180°out of phase operation
  • Synchronizable switching frequency from 150 kHz to 250 kHz
  • 4.5 V to 36 V input range
  • 50µA shutdown current
  • Adjustable output from 1.3 V to 90% of Vin
  • 0.04% (typical) line and load regulation error
  • Current mode control with or without a sense resistor (...)

Design tools & simulation

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
  • (...)
LM5642 Mathcad Design Tools

CAD/CAE symbols

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HTSSOP (PWP) 28 View options
TSSOP (PW) 28 View options

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