What is Shutdown Current (Isd) of an eFuse IC?

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Editorial Team - everything PE

Aug 9, 2023

Shutdown Current (Isd) is the current drawn by the eFuse IC when it is in its shutdown state. When an eFuse IC detects an overcurrent event and enters the shutdown mode, it is essential for it to consume as little current as possible. A low Isd value ensures that the eFuse doesn't dissipate much power during its shutdown state, which can lead to a reduced risk of thermal issues and enhance the overall system's reliability.

eFuse uses a test-and-repeat cycle sequence to assess if it is safe to restore the current flow

Benefits of low shutdown current

  • Power Efficiency: In battery-operated devices, low Isd helps conserve power, extending the battery life and improving the device's overall efficiency.
  • Heat Dissipation: As mentioned earlier, a low Isd minimizes power dissipation in the eFuse. Lower power dissipation translates to reduced heat generation, which is especially critical in high-power applications to prevent thermal stress on the IC and adjacent components.
  • Temperature and Aging Effects: High currents during the shutdown state can accelerate aging and decrease the reliability of the eFuse and other components. A low Isd helps mitigate these effects and ensures a longer operational lifespan.
  • Safe Parallel Operation: In certain applications, multiple eFuse ICs are connected in parallel to share the load current. A low Isd enables safe parallel operation since the overall shutdown current will remain within acceptable limits.

Factors Affecting Shutdown Current

  • Circuit Design: The design of the control and sensing circuitry, as well as the choice of the power switch, can impact the overall Isd value. Careful design optimization can lead to lower shutdown currents.
  • Technology and Manufacturing Process: The semiconductor process technology used to fabricate the eFuse IC plays a role in determining its characteristics, including the Isd. Advanced processes and manufacturing techniques can help achieve lower Isd values.
  • Operating Conditions: Temperature, voltage, and current levels under normal and fault conditions can affect Isd. Manufacturers often specify Isd values under specific conditions in the datasheet.

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