DocID17613 Rev 3

11/15

AN3236

Touchkey matrix

14

However, when two touchkeys are touched on different rows or columns, four channels are

detected and it is difficult to discriminate a true touch from a false one. This phenomenon is

known as the “ghost” effect.

In Figure 6, touchkey 1 and touchkey 5 are touched but, channels 1, 2, 4 and 5 are

detected. From the application, it is impossible to determine which of the four touchkeys are

touched.

Figure 6. Ghost effect example