Fault Protection & Diagnostics in Power ICs using Temperature Sensors

Fault conditions sensing for example, the detection of a short circuit is an integral part of many smart power integrated circuits (ICs)/power ICs. The ability to get temperature sensors in the semiconductor process provides protection and diagnostics as part of the features of these devices.

The main function of the power IC is to provide a microcontroller-to-load interface for a variety of loads. In multiple output devices, sensing the junction temperature of each device permits the status of each device to be provided to the microcontroller, and, if needed, the microcontroller can shut down a specific unit that has a fault condition.

A typical power IC can have multiple power drivers integrated on a single monolithic piece of silicon. Each of these drivers can have a temperature sensor integrated to determine the proper operating status and shut off only a specific driver if a fault occurs.

The octal serial switch (OSS) adds independent thermal sensing through over-temperature sensing circuitry to the protection features. Faults can be detected for each output device, and individual shutdown can be executed. In multiple output power IC, it is highly desirable to shut down only the device that is experiencing a fault condition and not all the devices that are integrated on the power IC. With outputs in various physical locations on the chip, it is hard to predict the thermal gradients that could occur in a fault situation.  Local temperature detection at each output, instead of a single global temperature sensor, is needed.

The over-temperature condition detected by the power IC could imply that the device turns itself OFF to avoid failure in one case; and in another situation, a fault signal provides a warning to the microcontroller but no action is taken, depending on the fault circuit design. The remaining portion of the system is allowed to operate normally. With the fault conditions supplied to the microcontroller, an orderly system shutdown can be executed. Integrated temperature sensing is essential to provide this type of protection in a multiple-output power IC.

Also read:

• Electronic IC Temperature Sensors
• Linear/Analog vs. Digital Integrated Circuits (ICs)
• NAMUR NE 107 Standard for Modern Instrumentation Diagnostics
• Process Instrumentation Diagnostics & Communication Interfaces