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 works unidirectionally, data is send in one direction 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
- Nevertheless multiple devices can be addressed sharing an I2C UfM bus. 112 nodes are 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.
NXP provides the application note AN11250 Practical guide for the use of Ultra Fast-mode I2C-bus