HDMI2C1-14HD Datasheet, PDF (14/32 Pages) STMicroelectronics – HPD pull down and signal conditioning

Application information
HDMI2C1-14HD
Table 1. Block diagrams references
Ref.
Typical values
Comment
R1
27 k
Pull-up resistance on CEC bus, specified by the HDMI standard
R2, R3
1.8 k
Pull-up resistances on DDC bus, specified by the HDMI standard
R4, R5
10 k
Pull-up resistance on DDC bus, ASIC side, value selected to be
compliant with I2C levels
R6
270 kto Pull-up resistance on CEC line, ASIC side
R7
10 k
Pull-up resistance on FAULT line (option)
D1
C1 to C5
BAT54
100 nF
Small Schottky diode blocking back drive current flowing toward the
V_{DD_CEC} supply
Decoupling capacitance on power supplies
C6
1 µF
ESD protection enhancement capacitance (option)
Note:
SCL_IC, SDA_IC, and CEC_IC have to be driven with an ASIC working with open drain
outputs.
Figure 14. PCB layout example
VDD_IC
VDD_CEC_IC
R6
CEC
driver
fault detect
DDC clock
DDC data
R5 R4
R7
SCL_IC
SDA_IC
HPD_IC
C6 _{ESD_DISCH}
DAT_D2+_IC
DAT_D2 -_IC
DAT_D1+_IC
DAT_D1 - _IC
DAT_D0+_IC
DAT_D0 -_IC
DAT_CK+_IC
DAT_CK- _IC
GND
HEAC+
HEAC -
VDD_CEC
5V_OUT
VDD_CEC_IC
VDD_5V
C3
C5
C1
C2
C4
VDD_CEC
VDD_5V
5V_OUT
nc
DAT_D2+
DAT_D2-
DAT_D1+
DAT_D1-
DAT_D0+
DAT_D0 -
DAT_CK+
DAT_CK -
VDD_CEC
D1 R1
5V_OUT
R3 R2
HDMI connector type A
TMDS Data2+
TMDS Data2 Shield
TMDS Data2 -
TMDS Data1+
TMDS Data1 Shield
TMDS Data1 -
TMDS Data0+
TMDS Data0 Shield
TMDS Data0 -
TMDS Clock+
TMDS Clock Shield
TMDS Clock -
CEC
Utility / HEAC+
SCL
SDA
DDC/CEC GND / HEAC shield
+5V power
HPD / HEAC -
The Figure 14 illustrates the fact that the HDMI2C1-14HD pin configuration eases and
optimizes the PCB layout of the HDMI interface. The proposed pin-out sequence is directly
compliant with HDMI connector type A.
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