### Capacitor Specifications

When you are looking for a capacitor for a particular application, it’s important to find a component that has the right specifications for the job. Here are two of the most important specifications to watch for.

#### Tolerance

Capacitors are rated according to how nearly their values can be expected to match the rated capacitance. The most common tolerance is 10%; some capacitors are rated at 5% or even at 1%. The lower (or tighter) the tolerance number, the more closely you can expect the actual component value to match the rated value. For example, a 10% capacitor rated at 100 pF can range from 90 to 110 pF. But if the tolerance is 1%, the manufacturer guarantees that the capacitance will be between 99 and 101 pF.

#### Problem 1

A capacitor is rated at 0.10 μF 10%. What is its guaranteed range of capacitance? First, multiply 0.10 by 10 percent to get the plus-or-minus variation. This is 0.10 × 0.10 = 0.010 μF. Then add and subtract this from the rated value to get the maximum and minimum possible capacitances. The result is a range of 0.09 to 0.11 μF.

#### Temperature Coefficient

Some capacitors increase in value as the temperature increases. These components have a positive temperature coefficient. Some capacitors decrease in value as the temperature rises; these have a negative temperature coefficient. Some capacitors are manufactured so that their values remain constant over a certain temperature range. Within this span of temperatures, such capacitors have zero temperature coefficient.

The temperature coefficient is specified in percent per degree Celsius (%/°C). Sometimes, a capacitor with a negative temperature coefficient can be connected in series or parallel with a capacitor having a positive temperature coefficient, and the two opposite effects cancel out over a range of temperatures. In other instances, a capacitor with a positive or negative temperature coefficient can be used to cancel out the effect of temperature on other components in a circuit, such as inductors