Offering 5 Mhz the I2C Ultra Fast-Mode UfM is the fasted I2C mode available. This mode is pretty different to other I2C modes:
- UfM work unidirectional, only
- Ultra Fast Mode lines are driven in push-pull technology
- Slaves do not send an acknowledge bit
- There is a single master only
- No arbitration for multi-master enviroment is available
Currently there are just a couple of devices supporting this mode. NXPs PCU 9669 is a 3 channel bus controller with two 5 MHz UfM and one fast-mode-plus FM+ interface. Variations are available.
Since the Ultra Fast Mode bus basically focusses on LED devices NXP comes with an LED Controller PCU9655.