TMS320DM8127_14 Datasheet, PDF (265/365 Pages) Texas Instruments – DaVinci Video Processors

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TMS320DM8127
SPRS712C – JUNE 2012 – REVISED MARCH 2014
Table 9-40. TMDS Routing Specifications (continued)
PARAMETER
TMDS differential pair to any other trace spacing
MIN
2*DS ⁽²⁾
TYP
(2) DS = differential spacing of the HDMI traces.
MAX UNIT
9.9.1.3 DDC Signals
As shown in Figure 9-37, HDMI Interface High-Level Schematic, the DDC connects just like a standard
I2C bus. As such, resistor pullups must be used to pull up the open drain buffer signals unless they are
integrated into the ESD protection chip used. If used, these pullup resistors should be connected to a 3.3-
V supply.
9.9.1.4 HDMI ESD Protection Device (Required)
Interfaces that connect to a cable such as HDMI generally require more ESD protection than can be built
into the outputs of the processor. Therefore, this HDMI interface requires the use of an ESD protection
chip to provide adequate ESD protection and to translate I2C voltage levels from the 3.3 V supplied by the
device to the 5 volts required by the HDMI specification.
When selecting an ESD protection chip, choose the lowest capacitance ESD protection available to
minimize signal degradation. In no case should the ESD protection circuit capacitance be more than 5 pF.
TI manufactures devices that provide ESD protection for HDMI signals such as the TPD12S521. For more
information see the www.ti.com website.
9.9.1.5 PCB Stackup Specifications
Table 9-41 shows the stackup and feature sizes required for HDMI.
Table 9-41. HDMI PCB Stackup Specifications
PARAMETER
MIN
PCB routing/plane layers
4
Signal routing layers
2
Number of ground plane cuts allowed within HDMI routing region
-
Number of layers between HDMI routing region and reference ground plane
-
PCB trace width
-
PCB BGA escape via pad size
-
PCB BGA escape via hole size
-
device BGA pad size⁽¹⁾⁽²⁾
(1) Non-solder mask defined pad.
(2) Per IPC-7351A BGA pad size guideline.
TYP
MAX UNIT
6
- Layers
3
- Layers
-
0 Cuts
-
0 Layers
4
- Mils
20
- Mils
10
Mils
0.4
mm
9.9.1.6 Grounding
Each TMDS channel has its own shield pin which should be grounded to provide a return current path for
the TMDS signal.
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