This section is for information only and subject to change depending upon system implementation. The pull-up resistor value is determined by two requirements:

1. The maximum sink current of the I²C buffer:

   The maximum sink current is 3mA or slightly higher for an I²C driver supporting standard-mode I²C operation.

   Equation 1. $R_{UP \left(min\right)}= \frac{V_{CC}}{I_{sink}}$

2. The maximum transition time on the bus:

   The maximum transition time, T, of an I²C bus is set by an RC time constant, where R is the pull-up resistor value, and C is the total load capacitance. The parameter, k, can be calculated from Equation 3 by solving for t, the times at which certain voltage thresholds are reached. Different input threshold combinations introduce different values of t. Table 8-2 provides the possible values of k under different threshold combinations.

   Equation 2. $T=k \times RC$
   Equation 3. $V\left(t\right)=V_{DD} \times (1-e^{\frac{-t}{RC}})$

From Equation 1, Rup(min) = 5.5V/3mA = 1.83kΩ to operate the bus under a 5-V pull-up voltage and provide less than 3mA when the I²C device is driving the bus to a low state. If a higher sink current, for example 4mA, is allowed, Rup(min) can be as low as 1.375kΩ.

If DDC working at standard mode of 100Kbps, the maximum transition time T is fixed, 1 μs, and using the k values provided in Table 8-2, then the recommended maximum total resistance of the pull-up resistors on an I²C bus can be calculated for different system setups. If DDC working in fast mode of 400Kbps, the transition time should be set at 300 ns according to I²C specification.

To support the maximum load capacitance specified in the HDMI specification, C_(cable)(max) = 700 pF, C_(source) = 50 pF,
C_I = 50 pF, R(max) can be calculated as provided in Table 8-3.

To accommodate the 3-mA drive current specification, a narrower threshold voltage range is required to support a maximum 800-pF load capacitance for a standard-mode I²C bus.