Figure 6. Benefit of the dynamic pull-up on the DDC bus

Signal on the cable

IC control

5V_OUT

VDD_IC

IC control

Signal on the cable

Rise time out of I2C specification

Risk of communication failure

Rise time compliant with I2C specification

Signal integrity even on 750pF load capacitance

RPU_BUS

5V_ OUT

HDMI™ cable model

750pF

RPU_BUS

5V_ OUT

HDMI™ cable model

750pF

I2C driver without dynamic pull-up

I2C driver with dynamic pull-up

In order to activate the DDC bus, both the following conditions must be respected: VDD_5V must be higher than

the VDD_ON threshold (see Table 3. Power supply characteristics (Tamb = 25 °C)), and all inputs and outputs

(SDA, SCL, SDA_IC, SCL_IC) must be set to a high level at the same time.

The DDC outputs (SCL and SDA on the cable side) integrate a protection against ESD, which is compliant with

IEC61000-4-2 standard, level 4 (8 kV contact).

HDMI2C1-6C1

DDC bus description

DS9943 - Rev 4

page 6/22