Reading Between the Lines - Understanding Datasheet Specifications

The information in a test equipment datasheet can be an important tool for understanding a unit’s features and whether it will fit your lab’s needs. But do these datasheets promise too much? We regularly get questions from engineers about units that do not perform as they would have expected based on the information in the datasheet. To address this mismatch between what’s outlined in the datasheet and the unit’s actual performance, we need to understand that not everything that is written in the datasheet is guaranteed.

In the test and measurement industry, each manufacturer has its own format and style of datasheet. And while there are terminologies that are used across board, the definitions of these terminologies often vary among manufacturers. Tempting as it may be to skip the definitions section of a datasheet and jump straight into the parameters, don’t.  It will help you understand the difference between these common terms: specification, typical and nominal.

Understanding Specification, Typical and Nominal

Specification is the most reliable set of data. It describes the product’s performance and characteristics that are covered by product warranty. It is also usually accompanied by tolerance limits. All specifications are normally tested in the manufacturing process within a specific environment, such as temperature range. Each piece of test equipment you purchase must meet and perform according to its specifications. If it doesn’t, send it for warranty repair or exchange, depending on the agreement with the manufacturer.

Some test equipment may actually perform better than the specifications. The possibility of this happening is, in fact, pretty high –up to an 80% chance. This is what is called typical performance. Typical performance is not warrantied, but most of the test equipment manufactured should perform to that level. Some manufacturers define typical performance as “performance beyond specification that 80% of the units exhibit with a 95% confidence level over a certain temperature range.” This performance may or may not be tested in the manufacturing process, but if you really need your test equipment to perform at this level, there’s often room to negotiate with the manufacturer to screen for such units – a sufficiently attractive purchase volume helps.

Another set of performance data which is not within the product guarantee - and rarer, too - is the nominal performance. This is the performance characteristic that is expected of the test equipment by design but is never tested in manufacturing.

Knowing these common terminologies and also reading the fine print of the datasheet can help you avoid the issue of your test equipment not meeting expectations. MAT tests all our equipment to ensure it conforms to the correct specifications. We can provide you with datasheets for your reference and can also review specifications for any piece of equipment in question. We also sell and lease Lab-Certified Pre-Owned Test Equipment from all major manufacturers, so please feel free to browse our inventory (check out the Downloads tab to see datasheets) or contact us today.