SCPS273C may 2019 – june 2023 TCA9548A-Q1
PRODUCTION DATA
Once all the targets are assigned to the appropriate target channels and bus voltages are identified, the pull-up resistors, Rp, for each of the buses need to be selected appropriately. The minimum pull-up resistance is a function of VDPUX, VOL,(max), and IOL as shown in Equation 1:
The maximum pull-up resistance is a function of the maximum rise time, tr (300 ns for fast-mode operation, fSCL = 400 kHz) and bus capacitance, Cb as shown in Equation 2:
The maximum bus capacitance for an I2C bus must not exceed 400 pF for fast-mode operation. The bus capacitance can be approximated by adding the capacitance of the TCA9548A-Q1, Cio(OFF), the capacitance of wires, connections and traces, and the capacitance of each individual target on a given channel. If multiple channels are activated simultaneously, each of the targets on all channels contribute to total bus capacitance.