How to read a datasheet
Absolute maximum ratings, recommended operating conditions, the electrical characteristics table, timing diagrams. Where to look first in tens of pages.
Reading order
- Feature list on the first page: is this chip right for my use?
- Pinout and pin descriptions: connect them to the schematic symbol
- Absolute maximum ratings: limits beyond which it is damaged. Not operating conditions
- Recommended operating conditions: the specifications are guaranteed only within these
- Electrical characteristics: the table of actual performance
- Application circuit and layout example: usually followed almost as drawn
Reading the electrical characteristics table
| Item | Min | Typ | Max | Conditions |
|---|---|---|---|---|
| Rds(on) | 8 mΩ | 12 mΩ | Vgs = 4.5 V, 25 °C |
Design with Max (or Min), not Typ. And always read the conditions column. A 25 °C value commonly becomes 1.5 times larger at 100 °C. The graph pages have curves for each temperature.
RoadmapSee where this note sits in Practical Components→Timing diagrams
For interfaces such as SPI and I2C, diagrams and tables show when data has to be stable relative to the clock edge (setup, hold). Find the symbols from the table (tSU, tH, tCLK) on the diagram and read them by matching the arrows.
Also
- Errata: the list of the chip's known bugs. Always check for an MCU
- Reference manual: an MCU has a datasheet (electrical specifications) and a separate reference manual (register descriptions)
- Application notes: design know-how compiled by the manufacturer. Friendlier than the datasheet