What Does the “R” Mean in TCAL6416R?

TCAL6416R is similar to TCAL6416. Read about the features of the TCAL6416 —> here.

The “R” adds what is known as a “sticky registers.” Some may know this as “sticky reset.”

The idea is that when /RESET is toggled, the registers of the TCAL6416R retain their pre-configured values. This is important, because while the /RESET pin does not reset the registers of the IO expander, it does reset the I2C state machine.

This feature is helpful during the case of a stuck bus condition where SDA is stuck LOW due to a false clock edge in the system. In this case, the user must toggle /RESET. Toggling /RESET for TCAL6416R will recover the SDA stuck bus condition if TCAL6416R was the device that was stuck. However, this reset condition will not set the register map back to its default state as shown in Table 7-4 of the datasheet. This saves immense amounts of re-boot time since the user will have to reprogram the TCAL6416R by re-writing I2C to each register in the map.

In the non-”R” version TCAL6416, toggling /RESET will reset the I2C state machine as well as the registers back to their power-up default state.

Power-Up Default State on Page 23/43 of the TCAL6416R Datasheet