The ISO1642, ISO1643 and ISO1644 intregrate unidirectional isolation channels, in addition to the bidirectional isolated I²C lines, to support system signals. The ISO1642 includes two channels in opposing directions (1/1 configuration) and the ISO1643 include two channels in the same direction (2/0 configuration). The ISO1644 includes three GPIO channels, two in one direction and one in the opposite direction (2/1 configuration) making it possible to use with a Serial Peripheral Interface (SPI). The conceptual block diagram of a unidirectional digital capacitive isolator channel is shown in Figure 8-3.

Figure 8-3 Conceptual Block Diagram of the GPIO Channels