The SC18IS602/602B and SC18IS603 are designed to serve as an interface between a standard I²C-bus of a microcontroller and an SPI bus. This allows the microcontroller to communicate directly with SPI devices through its I²C-bus. The SC18IS602/602B/603 operates as an I²C-bus slave-transmitter or slave-receiver and an SPI master. The SC18IS602/602B/603 controls all the SPI bus-specific sequences, protocol, and timing.
The SC18IS602/602B has its own internal oscillator, while the SC18IS603 requires an external clock source for operation. SC18IS602 and SC18IS603 do not support SS2 function as SPI slave select signal; this pin can only be used as GPIO2.