Ultra Fast Mode UFm

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.


NXP provides a video on the this I2C bus mode.