Hi there from the Texas Instruments voltage supervisor's product line. We present our series of short videos called Voltage Supervisors 101, where we will go over all of the basics for understanding and designing with supervisors. For the first video of the series, Overview of the Voltage Supervisor, we are going to talk about what is a voltage supervisor, when do I need a voltage supervisor, and how does a voltage supervisor work?

To begin, let's discuss the term voltage supervisor. As there isn't a standard industry definition, voltage supervisors are also called voltage detectors, voltage monitors, or even reset ICs. They are all the same devices, just with a different name across different manufacturers. So what is a voltage supervisor?

A voltage supervisor is a device that monitors or supervises a voltage rail and asserts a signal to enable, disable, or reset another device when that monitored rail falls below or rises above a predetermined threshold voltage. So now that we know what a supervisor is, when do we need to use a voltage supervisor?

Depending on the system requirements, wherever a voltage rail out of specification could lead to performance issues or system failure, a voltage supervisor can be utilized. For example, a DC to DC converter, or LDO, has a main supply rail that needs to be above a certain threshold voltage before it can power up correctly.

A voltage supervisor is used to monitor this rail to ensure it is online before asserting a signal to the converters enable pin allowing the converter to power up. The most common use case for voltage supervisors is that they are paired with microcontrollers and processors that often have multiple supply rails each with a tight window of accuracy. These rails require accurate supervisors to disable the processor when these voltages are out of spec to prevent brownout conditions.

So how does a voltage supervisor work? In this example, the supervisor is monitoring a 3.3 volt voltage rail. If the user determines that the system should yield an error if the monitored voltage rail falls below 2.93 volts, that user would select a supervisor with a 2.93 volt threshold voltage. In the case the voltage rail falls below 2.93 volts, the reset IC will assert its output, reset bar, and put the processor into reset mode until the supply voltage recovers.

This concludes our video for the overview of the voltage supervisor. Texas Instruments has one of the widest breadth of products and its voltage supervisors portfolio. To learn more, please visit us at www.ti.com/supervisors where you can find supervisors with different features, read our tech notes and blogs, and use the TI E to E support page to ask any questions.