SDAA247 January   2026 TPS2HCS10-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Melting Fuse Performance
    1. 2.1 Current Rating
    2. 2.2 Rerating Curve
    3. 2.3 I2T Values
      1. 2.3.1 Melting I2T
      2. 2.3.2 Arcing I2T
      3. 2.3.3 Total Clearing I2T
      4. 2.3.4 Fuse I2T Considerations
    4. 2.4 Opening Time
    5. 2.5 Voltage Rating
  6. 3TI Smart eFuse High-Side Switch Performance
    1. 3.1 Process/Voltage/Temperature Considerations
      1. 3.1.1 Max Operating Temperature
    2. 3.2 I2T Curve
      1. 3.2.1 Nominal Current Threshold (INOM)
      2. 3.2.2 I2T Fuse Threshold
      3. 3.2.3 Fixed-Delay Shutdown Threshold
      4. 3.2.4 Immediate Overcurrent Protection Threshold (IOCP)
    3. 3.3 Additional Protections and Diagnostics
      1. 3.3.1 Additional Protections
        1. 3.3.1.1 Short-to-Ground Protection
        2. 3.3.1.2 Capacitive Charging
        3. 3.3.1.3 Limp Home Mode/Watchdog/CRC
        4. 3.3.1.4 Reverse Battery Protection
        5. 3.3.1.5 Loss of Battery/Ground Protection
        6. 3.3.1.6 Integrated Inductive Discharge
      2. 3.3.2 Additional Diagnostics
  7. 4Switching from Melting Fuse to TI Smart eFuse High-Side Switch
    1. 4.1 Melting Fuse Design
    2. 4.2 Current Rating
    3. 4.3 I2T Trip Times
  8. 5Summary
  9. 6References

2.2 Rerating Curve

Since a fuse's trip point is based on its instantaneous temperature, any ambient temperature difference from its data sheet ratings will affect the current rating. A lower ambient temperature requires a greater temperature difference (current) to melt the internal wire, and a higher ambient temperature requires a lower temperature difference (current) to melt the internal wire. Fuse data sheets typically include a current rerating curve to help designers estimate the fuse's performance at different ambient temperatures.

For example, a typical fuse rerating curve details that the rerating factor at an 85°C ambient temperature is about 91%, so the 10A fuse from would have a rated current of 6.825A at 85°C according to Equation 1.

Equation 1. ReratedOperatingCurrent=CurrentRating*0.75*ReratingFactor
Example Melting Fuse Rerating CurveFigure 2-1 Example Melting Fuse Rerating Curve