What is the Correlation Between Voltage References and Current Sources?
Both current and voltage references are integral to analogue circuits. They help to provide regulated, fixed current or voltage to an IC and are essential for precision circuit applications.
What Causes Thermal Hysteresis in a Voltage Reference?
Thermal hysteresis occurs because of temperature cycling and it causes a voltage reference circuit's output to shift. This can be problematic as voltage references are required to provide a precise, reliable output over extended periods. Thermal hysteresis cannot be eliminated but its effects can be minimised. Thermal hysteresis typically follows a predictable maximum value. This is because, in subsequent cycles, many references vary around a nominal output voltage.
How to Choose a Reference Voltage for an ADC?
ADC reference voltage selection is important because analogue-to-digital (ADC) converters require reference voltage input for operation. The first step should be to decide the initial accuracy and voltage output level as this will determine the maximum voltage level that the ADC can convert. You should also consider the ADC's resolution. This can be determined by dividing the reference voltage by the number of potential conversion values. This reference voltage formula should help you to choose.
Additionally, when choosing a voltage reference for a circuit or system, it is important to look at other factors. Buying the best voltage reference for the task at hand should also involve an understanding of which other parameters will be especially relevant to the specific application you have in mind.
Initial accuracy specifications are one of the first criteria most buyers of voltage references usually search for on a manufacturer datasheet. In simple terms, the measured value when testing a product should always fall within the initial accuracy tolerance specified. However, while this specification is always provided by manufacturers and suppliers, it is usually only given for operation at room temperature and with a defined input voltage and load current. This means that it is a starting point for other specifications, but not necessarily an absolute value for all operating conditions and applications.
One factor known to influence initial accuracy tolerances is package stress, meaning that it is important that printed circuit board (PCB) flex is kept to a minimum even before the component is installed and powered. As a result, some industries and sectors will require new voltage reference devices to display manufacturer date stamps and will only accept parts up to a strict age limit for installation.