SDAA263 June   2026 TPS55289 , TPS55289-Q1 , TPS552892-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1E-latch System Introduction
    1. 1.1 Supercapacitor Characteristic
    2. 1.2 Typical Block Diagram of E-latch System
  5. 2 Supercapacitor Charging with Buck-boost Converter Based on CC/CV Control
    1. 2.1 Advantages of CC/CV Regulators for Supercapacitor Charging
    2. 2.2 Buck-Boost Dual-Loop With CC/CV
    3. 2.3 Output Current Monitoring
  6. 3Design Process
    1. 3.1 TPS5528x Family Part Selection
      1. 3.1.1 Current Capability
      2. 3.1.2 I2C Version and Non-I2C Version
      3. 3.1.3 Part Selection
    2. 3.2 Charge Voltage and Charge Current Setting
  7. 4Experimental Results
  8. 5Summary
  9. 6References

Abstract

This application note describes an emergency backup power system for an electronic door lock (E-latch) using five series-connected supercapacitors (5S). It also details the design and considerations of a buck-boost converter with constant current/constant voltage (CC/CV) charging for the supercapacitors. This design provides critical safety redundancy for automotive applications, by verifying that the door can still be unlocked in the event of a collision or main battery failure.