How to read datasheets
Which is the common pin-numbering convention for packages such as QFP and SOP?
- APin 1 is next to the index mark, and numbers increase clockwise when viewed from the top
- BPin 1 is next to the index mark, and numbers increase counterclockwise when viewed from the top
- CWith the package oriented so the marking is readable, pin 1 is at the bottom right and numbers increase to the left
Show answer and explanation
Answer: B. Pin 1 is next to the index mark, and numbers increase counterclockwise when viewed from the top
The top of the package has an index mark—a dimple, dot, notch or chamfer—and pin 1 is next to it. Pins 2, 3 and so on generally increase counterclockwise when viewed from the top. Always check whether the datasheet's pin diagram is a top view or a bottom view. In a bottom view, left and right appear reversed, and confusing the two leads to the mistake of a mirror-image footprint on the board. BGAs use numbers such as A1, with rows as letters and columns as numbers.