Switched-Cap Fast Charge Reference Design for USB Power Delivery Programmable Power Supply


Design files


The goal of this reference design is to show the total system performance when using the switched-cap fast charge topology in a smart phone application. The system includes using a smart wall adapter that supports USB Power Delivery (PD) Programmable Power Supply (PPS) specifications to reduce losses over the charging cable as well as reduce losses and the temperature rise in the smart phone. The bq25970 is the first switched-capacitor charger from TI that is capable of delivering up to 8A of charge current to a battery.

  • High efficiency charging 96.6% at 6A
  • Full system example for USB PD PPS voltage and current control
  • Software flow chart for phone and wall adapter
  • bq25890 for precharge, taper charge and termination
  • bq25970 for 6A charging with 3A cable current
  • TUSB422 USB PD controller for communication with smart wall adapter
Personal electronics
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A fully assembled board has been developed for testing and performance validation only, and is not available for sale.

Design files & products

Design files

Download ready-to-use system files to speed your design process.

TIDUDL7.PDF (1556 K)

Reference design overview and verified performance test data


Detailed schematic diagram for design layout and components


Complete listing of design components, reference designators, and manufacturers/part numbers


Detailed overview of design layout for component placement

TIDRVB6.ZIP (3059 K)

Files used for 3D models or 2D drawings of IC components

TIDCEF3.ZIP (1226 K)

Design file that contains information on physical board layer of design PCB

TIDRVB5.PDF (3414 K)

PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

Battery charger ICs

BQ25890I2C 1cell 5A buck battery charger Maxcharge™ tech for high input with D+/D-

Data sheet: PDF | HTML
Battery charger ICs

BQ25970I2C 1cell 8A switched cap battery charger for Parallel Charging Application and external OVP support

Data sheet: PDF | HTML
USB hubs & controllers

TUSB422USB PD TCPCi Port Controller

Data sheet: PDF | HTML
USB redrivers & multiplexers

TS3USB221High-Speed USB 2.0 (480 Mbps) 1:2 Multiplexer/Demultiplexer Switch With Single Enable

Data sheet: PDF | HTML

Technical documentation

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Type Title Date
* Design guide Switched-Cap Fast Charge Ref Design for USB PD Programmable Power Supply Sep. 25, 2017

Related design resources

Software development

BQSTUDIO Battery Management Studio (bqStudio) Software

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