Abstract

I²C bus is widely used in electronic systems for simplicity and low cost. For example, a precise DAC with I²C interface often was used to adjust the output voltage for high voltage power supply in medical systems such as ultrasound imaging, MRI, CT and so forth. In general, I²C was used in onboard communications between master and miscellaneous slaves such as low-speed ADC, low-speed DAC, GPIO, memory, sensors, and so on. However, designers sometimes must control remote slaves with I²C interface in another board potentially ten meters away. Long cable potential means big bus capacitance. The I²C standard specifies a maximum bus capacitance of 400pF for both Standard Mode and Fast Mode and specifies 550pF for Fast Mode Plus. As a result, long cable potential means the bus capacitance is out of the specification of I²C and potentially causes more error data rates. TI released two parts (P82B96 and P82B715) to solve this problem.