AD9889 Analog Devices, AD9889 Datasheet - Page 19

• Manufacturer Part Number: AD9889
• Description: High Performance HDMI/DVI Transmitter
• Manufacturer: Analog Devices

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The AD9889 has two modes for CTS generation: manual mode
and auto mode. In manual mode, the user can program the CTS
number directly into the chip (R0x07 to R0x09) and select this
external mode by setting R0x0A[7] to 1. In auto mode, the chip
computes the CTS based on the actual audio and video rates.
This can be selected by setting R0x0A[7] to 0, and the results
can be read from R0x04 to R0x06. Manual mode is good for
coherent audio and video, where the audio and video clock are
generated from the same crystal; thus CTS should be a fixed
number. The auto mode is good for incoherent audio-video,
where there is no simple integer ratio between the audio and
video clock. A filter is available (R0x0A[6:5]) to stabilize the
chip-generated CTS. The 20-bit N value can be programmed
into the AD9889 in Register R0x01 to Register R0x03.
PACKET CONFIGURATION
The AD9889 supports all the packets listed in the HDMI 1.1
specification. Each packet can be separately enabled and dis-
abled. Based on the audio and video input, the packets are
added to the HDMI link at the earliest time, so that a minimum
delay is incurred. Notice the ISRC1 packet has one bit to enable
the ISRC2 packet. For the general control packet, remember to
clear or reset the bits to avoid system lock-up.
Table 21. Pixel Repetition—Valid Pixel Repeat Values for Each Format
Video Code
1
2, 3
4
5
6, 7
8, 9
10, 11
12, 13
14, 15
16
17, 18
19
20
21, 22
23, 24
25, 26
27, 28
29, 30
31
32
33
34
1
Denotes change from EIA/CEA-861B valid values. Pixel repetition is required to support some audio formats at 720 × 480p and 720 × 576p video format timings.
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Video Description
640 × 480p @ 60 Hz
720 × 480p @ 59.94/60 Hz
1280 × 720p @ 59.94/60 Hz
1920 × 1080i @ 59.94/60 Hz
720/1440 × 480i @ 59.94/60 Hz
720/1440 × 240p @ 59.94/60 Hz
2880 × 480i @ 59.94/60 Hz
2880 × 240p @ 59.94/60 Hz
1440 × 480p @ 59.94/60 Hz
1920 × 1080p @ 59.94/60 Hz
720 × 576p @ 50 Hz
1280 × 720p @ 50 Hz
1920 × 1080i @ 50 Hz
720/1440 × 576i @ 50 Hz
720/1440 × 288p @ 50 Hz
2880 × 576i @ 50 Hz
2880 × 288 @ 50 Hz
1440 × 576p @ 50 Hz
1920 × 1080p @ 50 Hz
1920 × 1080p @ 23.97/24 Hz
1920 × 1080p @ 25 Hz
1920 × 1080p @ 29.9/30 Hz
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EIA/CEA-861B Pixel Repeat Values
Pixel sent 2 times
Pixel sent 2 times
Pixel sent 0 to 10 times
Pixel sent 1 to 10 times
No repetition
No repetition
No repetition
Pixel sent 2 times
Pixel sent 2 times
Pixel sent 1 to 10 times
Pixel sent 1 to 10 times
No repetition
No repetition
No repetition
No repetition
No repetition
No repetition
No repetition
No repetition
No repetition
No repetition
No repetition
Rev. 0 | Page 19 of 48
PIXEL REPETITION
Due to HDMI specification and bandwidth requirements,
sometimes it is necessary to set clock multiplication by 2× and
4× in order to maintain the minimum TMDS clock frequency.
The AD9889 offers three choices for the user to implement this
function: auto mode, manual mode, and max mode
(R0x3B[6:5]).
For the auto mode (R0x3B[6:5] = 00), based on the input video
format (either programmed by user, or chip detection) and
audio sampling rate, AD9889 automatically sets the pixel
repetition factor (R0x3D[7:6]).
For manual mode (R0x3B[6:5] = 1×), the user programs the
pixel repetition factor in R0x3B[4:3].
For max mode (R0x3B[6:5] = 01), based on the input video
format, the AD9889 selects the maximum repetition factor. The
advantage of the max mode is that it is independent of the audio
sampling rate.
HDMI Pixel Repeat Values
No repetition
No repetition
No repetition
No repetition
Pixel sent 2 times
Pixel sent 2 times
Pixel sent 1 to 10 times
Pixel sent 1 to 10 times
Pixel sent 1 to 2 times
No repetition
No repetition
No repetition
No repetition
Pixel sent 2 times
Pixel sent 2 times
Pixel sent 1 to 10 times
Pixel sent 1 to 10 times
Pixel sent 1 to 2 times
No repetition
No repetition
No repetition
No repetition
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