4.5V to 28V Input, 3A Output, Synchronous 350kHz FCCM Step-Down Converter


Product details


Vin (Min) (V) 4.5 Vin (Max) (V) 28 Vout (Min) (V) 1 Vout (Max) (V) 26 Iout (Max) (A) 3 Iq (Typ) (uA) 300 Switching frequency (Min) (kHz) 350 Switching frequency (Max) (kHz) 350 Features Enable, Forced PWM, Pre-Bias Start-Up, Synchronous Rectification, UVLO Adjustable, Soft Start Fixed Operating temperature range (C) -40 to 125 Rating Catalog Regulated outputs (#) 1 open-in-new Find other Buck converters (integrated switch)

Package | Pins | Size

SOT-23-THN (DDC) 6 open-in-new Find other Buck converters (integrated switch)


  • 4.5-V to 28-V Wide Input Voltage Range
  • Integrated 85-mΩ and 40-mΩ MOSFETs for 3-A, Continuous Output Current
  • Low 2-µA Shutdown, 300-µA Quiescent Current
  • Internal 5-mS Soft-Start
  • Fixed 350-kHz Switching Frequency
  • Peak Current Mode Control
  • Internal Loop Compensation
  • Overcurrent Protection for Both MOSFETs with Hiccup Mode Protection
  • Over Voltage Protection
  • Thermal Shutdown
  • SOT-23 (6) Package
  • Create a Custom Design Using the TPS54308 With the WEBENCH® Power Designer

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The TPS54308 is a 4.5-V to 28-V input voltage range, 3-A synchronous buck converter. The device includes two integrated switching FETs, internal loop compensation and 5-ms internal soft start to reduce component count.

By integrating the MOSFETs and employing the SOT-23 package, the TPS54308 achieves the high power density and offers a small footprint on the PCB.

The TPS54308 operates in force continous conduction mode (FCCM) during light load conditions, the switching frequency is maintained at an almost constant level over entire load range.

Cycle-by-cycle current limit in both high-side MOSFET protects the converter in an overload condition and is enhanced by a low-side MOSFET freewheeling current limit which prevents current runaway. Hiccup mode protection is triggered if the overcurrent condition has persisted for longer than the present time.

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Technical documentation

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Type Title Date
* Datasheet TPS54308 4.5-V to 28-V Input, 3-A Output, Synchronous 350-kHz FCCM Step-Down Converter in SOT23 Package datasheet Jan. 23, 2017
Selection guide Buck Converter Quick Reference Guide (Rev. A) Mar. 31, 2020
Application note Designing a Simple and Low-Cost Flybuck Solution With the TPS54308 (Rev. A) Oct. 14, 2019
Technical articles Minimize the impact of the MLCC shortage on your power application Mar. 29, 2019
Application note Using the TPS54x02 to Create an Inverting Power Supply Jun. 15, 2018
User guide TPS54308EVM-876 3-A Regulator Evaluation Module May 30, 2017

Design & development

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

Hardware development

The TPS54308 DC/DC converter is designed to provide up to a 3-A output from an input voltage source of 8 V to 28 V.  In order to aviod swtiching frequency drop into audio and introduce the audible issue under light load, the TPS54308 operates under force PWRM mode.

Th TPS54308EVM-876 evaluation (...)
  • Two 88mΩ/40mΩ MOSFET for 3A continuous output current
  • 0.6V internal voltage reference
  • Forced CCM operating mode
  • Monotonic start-up into pre-biased output

Design tools & simulation

SLUM585C.ZIP (798 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
  • (...)
SLUC685.ZIP (117 KB)

Reference designs

2-W auxiliary power supply for a single IGBT driver reference design
PMP40589 — This reference design is a dual-output, isolated fly-buck power module for a single IGBT driver bias using the TPS54308 synchronous buck converter. The converter generates one non-isolated output of +3.3 V with 400-mA current capability and two isolated outputs of +15 V and -8 V with 80-mA current (...)
document-generic Schematic

CAD/CAE symbols

Package Pins Download
SOT-23-THIN (DDC) 6 View options

Ordering & quality

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