ADV7180KCP32Z-RL Analog Devices Inc, ADV7180KCP32Z-RL Datasheet - Page 30

• Manufacturer Part Number: ADV7180KCP32Z-RL
• Description: 10-bit 4x Oversampling SDTV Decoder
• Manufacturer: Analog Devices Inc
• Type: Video Decoderr

Specifications of ADV7180KCP32Z-RL

• Design Resources: Low Cost Differential Video Receiver Using ADA4851 Amplifier and ADV7180 Video Decoder (CN0060) Low Cost Video Multiplexer for Video Switching Using ADA4853-2 Op Amp with Disable Function (CN0076)
• Applications: Digital Cameras, Mobile Phones, Portable Video
• Voltage - Supply, Analog: 1.71 V ~ 1.89 V
• Voltage - Supply, Digital: 1.65 V ~ 2 V
• Mounting Type: Surface Mount
• Package / Case: 32-LFCSP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ADV7180
DCT[1:0], Digital Clamp Timing, Address 0x15[6:5]
The clamp timing register determines the time constant of the
digital fine clamp circuitry. It is important to note that the digital
fine clamp reacts quickly because it immediately corrects any
residual dc level error for the active line. The time constant from
the digital fine clamp must be much quicker than the one from
the analog blocks.
By default, the time constant of the digital fine clamp is adjusted
dynamically to suit the currently connected input signal.
Table 34. DCT Function
DCT[1:0]
00 (default)
01
10
11
DCFE, Digital Clamp Freeze Enable, Address 0x15[4]
This register bit allows the user to freeze the digital clamp loop
at any time. It is intended for users who would like to do their
own clamping. Users should disable the current sources for
analog clamping via the appropriate register bits, wait until the
digital clamp loop settles, and then freeze it via the DCFE bit.
When DCFE is 0 (default), the digital clamp is operational.
When DCFE is 1, the digital clamp loop is frozen.
LUMA FILTER
Data from the digital fine clamp block is processed by the three
sets of filters that follow. Note that the data format at this point
is CVBS for CVBS input or luma only for Y/C and YPrPb input
formats.
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Luma antialias filter (YAA). The ADV7180 receives video
at a rate of 27 MHz. (In the case of 4× oversampled video,
the ADC samples at 57.27 MHz, and the first decimation is
performed inside the DPP filters. Therefore, the data rate
into the ADV7180 is always 27 MHz.) The ITU-R BT.601
recommends a sampling frequency of 13.5 MHz. The luma
antialias filter decimates the oversampled video using a high
quality linear phase, low-pass filter that preserves the luma
signal while at the same time attenuating out-of-band
components. The luma antialias filter (YAA) has a fixed
response.
Description
Slow (TC = 1 sec)
Medium (TC = 0.5 sec)
Fast (TC = 0.1 sec)
Determined by ADV7180, depending on the
input video parameters
Rev. F | Page 30 of 116
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Figure 22 through Figure 25 show the overall response of all filters
together. Unless otherwise noted, the filters are set into a typical
wideband mode.
Y Shaping Filter
For input signals in CVBS format, the luma shaping filters play
an essential role in removing the chroma component from a
composite signal. Y/C separation must aim for best possible
crosstalk reduction while still retaining as much bandwidth
(especially on the luma component) as possible. High quality
Y/C separation can be achieved by using the internal comb
filters of the ADV7180. Comb filtering, however, relies on the
frequency relationship of the luma component (multiples of the
video line rate) and the color subcarrier (f
CVBS signals, this relationship is known; the comb filter algorithms
can be used to separate luma and chroma with high accuracy.
In the case of nonstandard video signals, the frequency relationship
may be disturbed, and the comb filters may not be able to remove
all crosstalk artifacts in the best fashion without the assistance
of the shaping filter block.
Luma shaping filters (YSH). The shaping filter block is a
programmable low-pass filter with a wide variety of responses.
It can be used to selectively reduce the luma video signal
bandwidth (needed prior to scaling, for example). For
some video sources that contain high frequency noise,
reducing the bandwidth of the luma signal improves visual
picture quality. A follow-on video compression stage may
work more efficiently if the video is low-pass filtered.
The ADV7180 has two responses for the shaping filter: one
that is used for good quality composite, component, and SVHS
type sources, and a second for nonstandard CVBS signals.
The YSH filter responses also include a set of notches for
PAL and NTSC. However, using the comb filters for Y/C
separation is recommended.
Digital resampling filter. This block allows dynamic
resampling of the video signal to alter parameters such as
the time base of a line of video. Fundamentally, the resampler
is a set of low-pass filters. The actual response is chosen by the
system with no requirement for user intervention.
SC
). For good quality