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


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

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(Output Voltage 1)
(Output Voltage 2)
Vin (Min) (V)26.612
Vin (Max) (V)29.425
Vout (Nom) (V)2526.2
Iout (Max) (A)310
Output Power (W)75262
Input TypeDCDC
TopologyBuck- SynchronousBoost- Non Sync

TI Devices (3)

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Part Number Name Product Family Sample & Buy Design Kits & Evaluation Modules
BQ24640  High efficiency synchronous switch-mode battery charge controller for super capacitor  Battery management ICs  Sample & Buy View Design Kits & Evaluation Modules
TPS40210  4.5~52V Wide Input Range Boost/SEPIC/Flyback DC-DC Controller  Step-up (boost) regulators  Sample & Buy View Design Kits & Evaluation Modules
UCC27324  Non-inverting 4-A/4-A dual-channel low side gate driver  Gate drivers  Sample & Buy View Design Kits & Evaluation Modules

CAD/CAE symbols

Part # Package | Pins CAD File (.bxl) STEP Model (.stp)
BQ24640 Download Download
TPS40210 Download Download
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UCC27324 Download Download
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Technical documentation

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User guide (1)
Title Type Size (KB) Date
PDF 3459 28 Sep 2015
Design files (6)
Title Type Size (KB) Date
ZIP 40 28 Sep 2015
PDF 63 28 Sep 2015
ZIP 297 28 Sep 2015
PDF 690 28 Sep 2015
PDF 50 28 Sep 2015
PDF 48 28 Sep 2015

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