SDAA170 September   2026 TPS61383-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Design Requirement and System Structure
    1. 2.1 Design Requirements
    2. 2.2 System Structure
      1. 2.2.1 Centralized E‑Latch System
      2. 2.2.2 Distributed E‑Latch System
  6. 3Power Train
    1. 3.1 Integrated E-Latch Power Train with TPS61383-Q1
      1. 3.1.1 Super Capacitor Charger Function Introduction
      2. 3.1.2 Boost Function Introduction
      3. 3.1.3 Super Capacitor Bleeding
    2. 3.2 Hardware Design Procedure
      1. 3.2.1 Selecting the External MOSFET
      2. 3.2.2 Inductor Selection
      3. 3.2.3 Capacitor in Super Capacitor Side
      4. 3.2.4 Boost Output Capacitor
      5. 3.2.5 Loop Compensation Design
      6. 3.2.6 Key Considerations
    3. 3.3 Software Initial Process
  7. 4Super Capacitor Energy Modeling Basis and Selection
    1. 4.1 Discharge Profile and Cut-off Voltage
    2. 4.2 Super Capacitor Discharge Energy Modeling
    3. 4.3 Calculation Example
    4. 4.4 Super Capacitor Excel Calculation Tool
  8. 5Super Capacitor Management
    1. 5.1 Voltage Monitoring with BQ76907-Q1
    2. 5.2 Cell Balancing with BQ76907-Q1
      1. 5.2.1 Balancing Strategy
      2. 5.2.2 I2C Implementation
      3. 5.2.3 Cell Balancing Current
      4. 5.2.4 Low-Side Protection Circuit Design Considerations
    3. 5.3 Super Capacitor Health Detection: Combined Solution of TPS61383-Q1 and BQ76907-Q1
  9. 6Control Unit and Communication
    1. 6.1 Control Unit Design Consideration
    2. 6.2 SBC Selection
  10. 7Execution Unit
    1. 7.1 Motor Driver Structure
    2. 7.2 Motor Driver Design Considerations
  11. 8Summary
  12. 9References

4.4 Super Capacitor Excel Calculation Tool

The e‑latch actuator is typically a small brushed DC motor (rated 6V–12V) that drives a gear train to release the latch mechanism. A typical motor unlock load profile consists of three stages: Start up, Steady state and Stall. This load profile cycle continues for 12-20 times, which complicates the calculation on super capacitor energy. TI provides an Excel calculation tool to achieve fast, accurate calculation and help with the system design. The calculation tool is availablehere:

Assuming a e-latch system with below load profile:

Table 4-2 Design Requirement Example
Item Parameter
Cell Number 3s
Super Capacitor Voltage 2.7V per cell, 8.1V total
Super Capacitor Capacitance 25F per cell, 8.33F total
Super Capacitor Internal Resistance 25mΩ per cell, 90mΩ total
Load Profile Start State: 5A, 20ms
Steady State: 3A, 150ms
Stall: 8A, 50ms
Unlock Rounds 6 locks, 2 rounds each, 12 rounds total

Input these parameters and click the button to calculate discharge profile. The calculation can take some time. After calculation is completed, the tool shows Calculation Complete and update discharge curve.

Super Capacitor Calculation Tool Figure 4-3 Super Capacitor Calculation Tool

As previously mentioned in Figure 4-2. When high current is applied and equivalent ROUT is lower than internal resistance RIN, the Vout drops and cannot be sustained. In this case, TI recommends selecting a super capacitor with lower ESR or adding cell number.

Voltage Cannot Sustain Figure 4-4 Voltage Cannot Sustain