JAJSN80E August 2009 – May 2022 TCA9535
PRODUCTION DATA
The pull-up resistors, RP, for the SCL and SDA lines need to be selected appropriately and take into consideration the total capacitance of all targets on the I2C bus. The minimum pull-up resistance is a function of VCC, VOL,(max), and IOL as shown in Equation 5.
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 6.
The maximum bus capacitance for an I2C bus must not exceed 400 pF for standard-mode or fast-mode operation. The bus capacitance can be approximated by adding the capacitance of the TCA9535, Ci for SCL or CIO for SDA, the capacitance of wires/connections/traces, and the capacitance of additional targets on the bus. For further details, refer to I2C Pull-up Resistor Calculation application report, SLVA689.