A practical guide to the test method, protection mechanisms, and reliability results behind your automotive design

Modern vehicles are more electrically complex than ever. From advanced driver assistance systems to multi-zone infotainment, the wire harnesses connected to a vehicle's 12V power distribution network keep growing in complexity, and with them, the risk of short circuits.

Smart high-side switches are increasingly replacing traditional fuses and relays. They detect faults autonomously, protect the circuit, and can recover through software without requiring a workshop visit.

When a short circuit occurs in a vehicle, fault validation is required before the affected load is disabled. As a result, the load may be repeatedly reactivated while the short circuit remains present. OEMs expect a smart switch to withstand repeated faults over the vehicle's lifetime. For engineers selecting a device, the key question is simple: how can you prove that a switch will survive this repeated stress? AEC-Q100-012 provides an answer.

What is a short-circuit and why does it keep happening?

A short-circuit is an abnormal low-ohmic connection between two nodes of an electric circuit intended to be at different voltages. In a 12V automotive system, the two fault scenarios of concern are a short-circuit to ground (the most common for high-side switches) and a short-circuit to battery voltage. What makes short-to-GND faults particularly challenging is that they are often persistent and can drive currents far beyond normal operating levels, causing significant electrical and thermal stress. A damaged wire harness doesn't fail once, it fails repeatedly until it gets fixed.

OEMs translate this directly into device requirements. For every application, they define a minimum number of short-circuit cycles a device must survive. The exact figure depends on how often faults are expected to occur and the restart strategy is built into the system software.

What is AEC-Q100-012?

AEC-Q100-012 is a standardized procedure for characterizing repetitive short-circuit endurance in smart power devices used in 12V automotive systems.

Developed by the Automotive Electronics Council together with leading semiconductor suppliers, it creates a common basis for comparing device endurance across technologies and manufacturers. 

Without a common standard, each manufacturer would characterize short-circuit endurance using different methods and conditions, making any comparison of the results meaningless. AEC-Q100-012 solves this by defining:

  • A common test circuit with standardized supply and harness impedances
  • Specific test points for terminal and short-circuit load conditions
  • Three distinct microcontroller (MCU) reactivation scenarios that reflect real in-vehicle behavior
  • Clear failure criteria and grade-level reporting so results can be compared across products and technologies

Infineon plays an active role in developing the standard and uses it as a mandatory qualification step for relevant automotive PROFET™ and SPOC™ smart power switch families where repetitive short-circuit characterization applies.

How does AEC-Q100-012 testing work?

AEC-Q100-012 focuses on short-circuit type 1, in which the fault is already present before the microcontroller switches the device on. This provides a reproducible, technology-neutral basis for testing.

AEC-Q100-012 defines three scenarios which need to be selected based on the protection concept and status feedback of the smart power device. Before setting up a characterization test, identify which one applies to your device:

1. Cold repetitive – short pulse:

The MCU switches off the channel within 10 ms of detecting the fault, then waits for the device to cool fully before reactivating. This applies to devices without auto-restart, such as the PROFET™ +2 BTS7002-1ESP.

2. Cold repetitive – long pulse:

The MCU takes up to 300 ms to respond before switching off, then waits for the device to cool fully before reactivating the channel. The longer active phase means more energy is dissipated per cycle than in the short-pulse scenario.

3. Hot repetitive:

The MCU never switches the channel off, so the device never cools, junction temperature builds cycle by cycle, and the device keeps toggling close to the shut down temperature. This worst-case thermal scenario applies to devices with continuous auto-restart behavior.

Note: The terms "hot" and "cold" refer to the thermal state of the device between cycles, not the ambient test temperature.

How does Infineon implement AEC-Q100-012?

Infineon characterizes all PROFET™ devices using ACUTE (Active Cycle Universal Test Equipment) – its purpose-built platform for AEC-Q100-012 testing. 

What does the test circuit look like? 

The standard test circuit connects the PROFET™ device between a 14 V supply and a controlled short-circuit path to ground. On the supply side, inductance (5 µH) and resistance (10 mΩ) remain constant across all test points. The short-circuit path differs across four test points:

*Additional test point defined by Infineon to cover high-current devices beyond the AEC standard. 

Although AEC-Q100-012 permits ±20% tolerance on all wire impedance values, Infineon tests all devices as close as possible to the specified values. This ensures that the results are directly comparable across devices and product families, giving you a true picture of device performance.

Which protection mechanisms are involved?

Understanding how a PROFET™ device responds under AEC-Q100-012 conditions means understanding the three integrated protection mechanisms that govern its behavior during a short-circuit event:

1. Absolute overtemperature protection

The device continuously compares junction temperature against a fixed threshold – between 150°C and 200°C for AEC-Q100 grade 1 devices. When the threshold is reached, the switch turns off autonomously, regardless of the MCU command. 

2. Dynamic overtemperature protection

Rather than monitoring absolute temperature, dynamic overtemperature protection tracks how quickly the junction is heating up relative to a cooler reference point elsewhere in the device. At Infineon, that threshold is typically 80 K. This approach makes dynamic overtemperature protection sensitive to sudden thermal spikes that overtemperature protection alone might miss. It also helps you catch dangerous transients before they reach the absolute limit. PROFET™ +2 and SPOC™ +2 families both include dynamic overtemperature protection.

3. Overcurrent protection

The device continuously monitors the output current against a threshold. When that threshold is exceeded, it either trips off immediately or limits the current until overtemperature protection takes over. How that threshold is set varies across the PROFET™ family, whether it is fixed, adjustable, or digitally configurable. 

These three mechanisms interact differently depending on which combination your device implements. This is why test temperature selection requires careful engineering judgement.

How do you choose the right test temperature?

For cold repetitive testing on devices with only absolute overtemperature protection, AEC recommends setting the ambient temperature to the minimum specified value – typically -40°C. This maximizes the thermal headroom before the overtemperature protection threshold is reached.

For devices combining absolute overtemperature protection with dynamic overtemperature protection, the most stressful starting condition isn't the coldest. The typical worst-case operating condition is at the maximum ambient temperature, where the complete dynamic overtemperature protection swing can be utilized.

For hot repetitive testing, the standard specifies an ambient temperature of +25°C with forced airflow. Since the device never cools between cycles, the junction temperature accumulates rapidly from the first event and remains elevated throughout.

 

How are the results evaluated?

Infineon terminates a test either when 50% of devices have failed or after its extended limits of 1,000 hours (hot) or 1,001,000 cycles (cold), then evaluates the results in two ways: by grade level and by statistical analysis.

1. By grade level

Infineon assigns a grade level based on the cycle count at first failure — or the total cycles if a failure doesn’t occur. The PROFET™ +2 BTS7004-1EPP reached the full 1,001,000-cycle limit without failure, earning Grade A.

2. By statistical analysis

If enough failures occur, Infineon also runs a statistical evaluation. Infineon fits the results to a Lognormal or Weibull distribution and reports CTF values at 100 ppm and 1,000 ppm – the cycle counts at which 0.01% and 0.1% of the population are expected to fail. These give system engineers the data they need for reliability modelling.

ACUTE characterization reports for PROFET™ and SPOC™ devices are available on the Infineon Collaboration Platform for registered users.

How does AEC-Q100-012 testing work?

AEC-Q100-012 focuses on short-circuit type 1, in which the fault is already present before the microcontroller switches the device on. This provides a reproducible, technology-neutral basis for testing.

AEC-Q100-012 defines three scenarios which need to be selected based on the protection concept and status feedback of the smart power device. Before setting up a characterization test, identify which one applies to your device:

1. Cold repetitive – short pulse:

The MCU switches off the channel within 10 ms of detecting the fault, then waits for the device to cool fully before reactivating. This applies to devices without auto-restart, such as the PROFET™ +2 BTS7002-1ESP.

2. Cold repetitive – long pulse:

The MCU takes up to 300 ms to respond before switching off, then waits for the device to cool fully before reactivating the channel. The longer active phase means more energy is dissipated per cycle than in the short-pulse scenario.

3. Hot repetitive:

The MCU never switches the channel off, so the device never cools, junction temperature builds cycle by cycle, and the device keeps toggling close to the shut down temperature. This worst-case thermal scenario applies to devices with continuous auto-restart behavior.

Note: The terms "hot" and "cold" refer to the thermal state of the device between cycles, not the ambient test temperature.

How does Infineon implement AEC-Q100-012?

Infineon characterizes all PROFET™ devices using ACUTE (Active Cycle Universal Test Equipment) – its purpose-built platform for AEC-Q100-012 testing. 

What does the test circuit look like? 

The standard test circuit connects the PROFET™ device between a 14 V supply and a controlled short-circuit path to ground. On the supply side, inductance (5 µH) and resistance (10 mΩ) remain constant across all test points. The short-circuit path differs across four test points:

*Additional test point defined by Infineon to cover high-current devices beyond the AEC standard. 

Although AEC-Q100-012 permits ±20% tolerance on all wire impedance values, Infineon tests all devices as close as possible to the specified values. This ensures that the results are directly comparable across devices and product families, giving you a true picture of device performance.

Which protection mechanisms are involved?

Understanding how a PROFET™ device responds under AEC-Q100-012 conditions means understanding the three integrated protection mechanisms that govern its behavior during a short-circuit event:

1. Absolute overtemperature protection

The device continuously compares junction temperature against a fixed threshold – between 150°C and 200°C for AEC-Q100 grade 1 devices. When the threshold is reached, the switch turns off autonomously, regardless of the MCU command. 

2. Dynamic overtemperature protection

Rather than monitoring absolute temperature, dynamic overtemperature protection tracks how quickly the junction is heating up relative to a cooler reference point elsewhere in the device. At Infineon, that threshold is typically 80 K. This approach makes dynamic overtemperature protection sensitive to sudden thermal spikes that overtemperature protection alone might miss. It also helps you catch dangerous transients before they reach the absolute limit. PROFET™ +2 and SPOC™ +2 families both include dynamic overtemperature protection.

3. Overcurrent protection

The device continuously monitors the output current against a threshold. When that threshold is exceeded, it either trips off immediately or limits the current until overtemperature protection takes over. How that threshold is set varies across the PROFET™ family, whether it is fixed, adjustable, or digitally configurable. 

These three mechanisms interact differently depending on which combination your device implements. This is why test temperature selection requires careful engineering judgement.

How do you choose the right test temperature?

For cold repetitive testing on devices with only absolute overtemperature protection, AEC recommends setting the ambient temperature to the minimum specified value – typically -40°C. This maximizes the thermal headroom before the overtemperature protection threshold is reached.

For devices combining absolute overtemperature protection with dynamic overtemperature protection, the most stressful starting condition isn't the coldest. The typical worst-case operating condition is at the maximum ambient temperature, where the complete dynamic overtemperature protection swing can be utilized.

For hot repetitive testing, the standard specifies an ambient temperature of +25°C with forced airflow. Since the device never cools between cycles, the junction temperature accumulates rapidly from the first event and remains elevated throughout.

 

How are the results evaluated?

Infineon terminates a test either when 50% of devices have failed or after its extended limits of 1,000 hours (hot) or 1,001,000 cycles (cold), then evaluates the results in two ways: by grade level and by statistical analysis.

1. By grade level

Infineon assigns a grade level based on the cycle count at first failure — or the total cycles if a failure doesn’t occur. The PROFET™ +2 BTS7004-1EPP reached the full 1,001,000-cycle limit without failure, earning Grade A.

2. By statistical analysis

If enough failures occur, Infineon also runs a statistical evaluation. Infineon fits the results to a Lognormal or Weibull distribution and reports CTF values at 100 ppm and 1,000 ppm – the cycle counts at which 0.01% and 0.1% of the population are expected to fail. These give system engineers the data they need for reliability modelling.

ACUTE characterization reports for PROFET™ and SPOC™ devices are available on the Infineon Collaboration Platform for registered users.

Deepen your knowledge with our online training

Want to learn more about AEC-Q100-012 characterization? Infineon's online training course "How to characterize repetitive short-circuit performance in accordance with AEC-Q100-012" walks you through the full methodology with interactive visuals and worked examples. From test setup to result interpretation, it's the fastest way to get hands-on confidence before you start your design.

Watch now!

Ready to find the right PROFET™ device for your application? Explore Infineon's full portfolio of PROFET™ 12V automotive smart high-side switches and access ACUTE characterization reports at infineon.com.