|ADV7182||10-Bit, SDTV Video Decoder with Differential Inputs|
|ADV7182 Datasheet PDF : 96 Pages |
The ADV7182 automatically detects and converts standard
analog baseband video signals compatible with worldwide NTSC,
PAL, and SECAM standards into a 4:2:2 component video data
stream. This video data stream is compatible with the 8-bit ITU-R
BT.656 interface standard.
External HS, VS, and FIELD signals can provide timing references
for LCD controllers and other video ASICs. The accurate 10-bit
analog-to-digital conversion provides professional quality video
performance for consumer applications with true 8-bit data
resolution. The analog video inputs accept both single-ended,
pseudo-differential, and fully differential composite video signals
as well as S-Video and YPbPr video signals, supporting a wide
range of consumer and automotive video sources.
The ADV7182 along with an external resistor divider provide a
common-mode input range of 4 V, enabling the removal of large
signal, common-mode transients present on the video lines.
Common-mode rejection (CMR) values of up to 80 dB can be
achieved without the need for external amplifier circuitry
The AGC and clamp restore circuitry allow an input video signal
peak-to-peak range to 1.0 V at the analog video input pin of the
ADV7182. Alternatively, these can be bypassed for manual settings.
The ADV7182 can be protected from short-to-battery (STB)
events with standard ac coupling capacitors.
The ADV7182 is programmed via a two-wire, serial bidirectional
port (I2C® compatible) and is fabricated in a 1.8 V CMOS process.
Its monolithic CMOS construction ensures greater functionality
with lower power dissipation. The LFCSP package options make
the decoder ideal for space-constrained portable applications.
The ADV7182 is a versatile one-chip multiformat video decoder
that automatically detects PAL, NTSC, and SECAM standards in
the form of composite, S-Video, and component video. The
ADV7182 can receive composite signals in either single-ended
or differential modes. This makes the ADV7182 ideal for
The ADV7182 converts these analog video formats into a
digital 8-bit ITU-R BT.656 video stream.
The digital video output stream of the ADV7182 interfaces
easily to a wide range of MPEG encoders, codecs, mobile video
processors, and Analog Devices, Inc., digital video encoders, such
as the ADV7391. External HS, VS, and FIELD signals provide
timing references for LCD controllers and other video ASICs.
OVERVIEW OF THE ANALOG FRONT END
The ADV7182 analog front end (AFE) comprises a single high
speed, 10-bit ADC that digitizes the analog video signal before
applying it to the standard definition processor. The AFE employs
differential channels to the ADC to ensure high performance in
mixed-signal applications and to enable differential CVBS to be
connected directly to the ADV7182
The front end also includes a 3-channel input mux that enables
multiple composite video signals to be applied to the ADV7182.
Current clamps are positioned in front of the ADC to ensure
that the video signal remains within the range of the converter.
A resistor divider network is required before each analog input
channel to ensure that the input signal is kept within the range
of the ADC (see Figure 23). The choice of this resistor divider
ratio provides a common-mode range of up to 4 V. Fine clamping
of the video signal is performed downstream by digital fine
clamping within the ADV7182.
Table 1 shows the three ADC clocking rates that are determined
by the video input format to be processed. These clock rates ensure
4× oversampling per channel for CVBS, Y/C, and YPrPb modes.
The ADV7182 has a fully differential AFE. This allows for inherent
small and large signal noise rejection, improved electromagnetic
interference (EMI), and the ability to absorb ground bounce.
Support is offered for both true differential and pseudo-
Table 1. ADC Clock Rates
ADC Clock Rate (MHz)1
Rate per Channel
1 Based on a 28.63636 MHz clock input to the ADV7182.
2 See INSEL[4:0] in Table 95 for writes needed to set Y/C (S-Video) and YPrPb
Rev. A | Page 3 of 96
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