28Vdc Input Super Cap Charger with Boost Converter for Bus Holdup Reference Design


Design files


This reference design uses the BQ24640 super cap charging controller to charge a large bank of super caps to a voltage below the input bus voltage. During an input bus dropout, the energy from the super caps is used to power a boost converter that can supply 10A of output current at 26.2V. This output can be used to hold up the bus voltage for up to 10 seconds (260W for 10 sec).

  • Boost Converter efficiency greater than 95% at Vin = 18V and 1A - 10A loads
  • Boost holdup supports 28V bus for longer than 27 seconds using a large 28F super cap bank while delivering 260W
  • Super cap charger provides a constant 3A charge current for a controlled startup time
  • Low cost design requires less than 100mm x 100mm
Output voltage options PMP7327.1 PMP7327.2
Vin (Min) (V) 26.6 12
Vin (Max) (V) 29.4 25
Vout (Nom) (V) 25 26.2
Iout (Max) (A) 3 10
Output Power (W) 75 262
Isolated/Non-Isolated Non-Isolated Non-Isolated
Input Type DC DC
Topology Buck- Synchronous Boost- Non Sync

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.


Test results for the reference design, including efficiency graphs, test prerequisites and more


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


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

SLUC426A.ZIP (297 K)

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


PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

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Technical documentation

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Type Title Date
* Test report PMP7327 Test Results (Rev. A) Sep. 28, 2015

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