SLUAAO7 March   2023 BQ24640 , BQ25173 , BQ25713 , BQ25798

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction
  4. 2Supercapacitors Charging Key Care-Abouts and Implementations
    1. 2.1 Supercap Charge Profile
    2. 2.2 Linear Based Supercap Charger
    3. 2.3 Switch-Mode Buck Converter Based Supercap Charger
    4. 2.4 Modifying Li-ion Chargers to Charge Supercaps
    5. 2.5 Using a Li-ion Buck-Boost Integrate FET Charger to Charge a Supercap or Li-ion Battery
    6. 2.6 Using a Buck-Boost Controller with External FETs to Charge a Supercap
  5. 3Summary
  6. 4References

3 Summary

This application note's supercap charging designs can be easily scaled to fit larger or higher voltage supercaps by changing the charge voltages and or charge currents. The key concern, and charge time variable, is how the charging circuit manages its high power losses and heat dissipation until the supercap voltage reaches a manageable voltage level. Table 3-1 compares the options,

Table 3-1 Supercap Charging Design Options
DesignInput Power

Voltage

CapacitanceCharge CurrentCharge TimeOther features
BQ25173 linear charger> V(REG)Low< 1 AlongSmall size
BQ24640 buck charger> V(REG)Med-High>1 A but < 10 AShort - medium
BQ25798 b-b charger plus TPS25221 switch<or > V(REG)Med-High>1 A but <5 AmediumLiIon or supercap charging with host software
BQ25713/30 b-b controller<or > V(REG)High>2 A but < 20 Ashort