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## TDP158 Datasheet(PDF) 43 Page - Texas Instruments

 Part No. TDP158 Description 6-Gbps, AC-Coupled to TMDS or HDMI Redriver Download 55 Pages Scroll/Zoom 100% Maker TI1 [Texas Instruments] Homepage http://www.ti.com Logo

## TDP158 Datasheet(HTML) 43 Page - Texas Instruments

 43 / 55 page tRCDDV(t) V(1e)uTkRCuCCUP(min)sinkVRI43TDP158www.ti.comSLLSEX2 – DECEMBER 2016Submit Documentation FeedbackCopyright © 2016, Texas Instruments Incorporated9.2.2.2 DDC Pull Up ResistorsThis section is for information only and subject to change depending upon system implementation. The pull-upresistor value is determined by two requirements:1. The maximum sink current of the I2C buffer:The maximum sink current is 3 mA or slightly higher for an I2C driver supporting standard-mode I2Coperation.(1)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 resistorvalue, and C is the total load capacitance. The parameter, k, can be calculated from Equation 3 by solvingfor t, the times at which certain voltage thresholds are reached. Different input threshold combinationsintroduce different values of t. Table 28 summarizes the possible values of k under different thresholdcombinations.(2)(3)Table 28. Value k upon Different Input Threshold VoltagesVth-\Vth+0.7 VCC0.65 VCC0.6 VCC0.55 VCC0.5 VCC0.45 VCC0.4 VCC0.35 VCC0.3 VCC0.1 VCC1.09860.94450.81090.69310.58780.49250.40550.32540.25130.15 VCC1.04150.88730.75380.63600.53060.43530.34830.26830.19420.2 VCC0.98080.82670.69310.57540.47000.37470.28770.20760.13350.25 VCC0.91630.76210.62860.51080.40550.31020.22310.14310.06900.3 VCC0.84730.69310.55960.44180.33650.24120.15420.0741From Equation 1, Rup(min) = 5.5 V/3 mA = 1.83 kΩ to operate the bus under a 5-V pull-up voltage and provideless than 3 mA when the I2C device is driving the bus to a low state. If a higher sink current, for example 4 mA,is allowed, Rup(min) can be as low as 1.375 kΩ.If DDC working at standard mode of 100 Kbps, the maximum transition time T is fixed, 1 μs, and using the kvalues from Table 28, the recommended maximum total resistance of the pull-up resistors on an I2C bus can becalculated for different system setups. If DDC working in fast mode of 400 Kbps, the transition time should be setat 300 ns according to I2C specification.To support the maximum load capacitance specified in the HDMI spec, C(cable)(max) = 700 pF, C(source) = 50 pF,CI = 50 pF, R(max) can be calculated as shown in Table 29.Table 29. Pull-Up Resistor Upon Different Threshold Voltages and 800-pF LoadsVth-\Vth+0.7 VCC0.65 VCC0.6 VCC0.55 VCC0.5 VCC0.45 VCC0.4 VCC0.35 VCC0.3 VCCUNIT0.1 VCC1.141.321.541.82.132.543.083.844.97KΩ0.15 VCC1.21.411.661.972.362.873.594.666.44KΩ0.2 VCC1.271.511.82.172.663.344.356.029.36KΩ0.25 VCC1.361.641.992.453.084.035.68.7418.12KΩ0.3 VCC1.481.82.232.833.725.188.1116.87------KΩTo accommodate the 3-mA drive current specification, a narrower threshold voltage range is required to supporta maximum 800-pF load capacitance for a standard-mode I2C bus.