HDMI2C1-6C1 Datasheet, PDF (6/23 Pages) STMicroelectronics – ESD protection and signal booster for HDMI source control stage interface

Application information
HDMI2C1-6C1
Figure 5. Simplified view of the electrical parameters of the DDC functional block
SDA_IC
VDD_IC
Vtup_IC
V _{Tdown_IC}
t
SDA
5V_OUT
70%
30%
V_{Tdown_BUS}
Vtup_BUS
VHYST_BUS
t
T _{FALL_BUS}
T _{RISE_BUS}
Source IC drives
Sink drives through HDMI cable
The HDMI™ standard specifies that the max capacitance of the cable can reach up to
700 pF. Knowing that the max capacitance of the sink input can reach up to 50 pF, this
means that the I2C driver must be able to drive a load capacitance up to 750 pF. On the
other hand, the I2C standard specifies a maximum rise time of the signal must be lower than
1 µs in order to keep the signal integrity. Taking into account the max cable capacitance of
750 pF, it is not possible to guarantee a rise time lower than 1 µs in worst case. Therefore, a
dynamic pull-up has been integrated at the output of SDA and SCL lines and synchronized
with the I2C driver. This signal booster accelerates for a short period the charging time of
the equivalent cable capacitance, allowing driving any HDMI™ cable. The Figure 6
illustrates the benefit of the dynamic pull-up integrated in the HDMI2C1-6C1 device.
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