ADV7181 Datasheet, PDF (12/96 Pages) Analog Devices – Multiformat SDTV Video Decoder

ADV7181B
ANALOG FRONT END
ADC_SW_MAN_EN
AIN2
AIN1
AIN4
AIN3
AIN6
AIN5
AIN4
AIN3
AIN6
AIN5
AIN6
AIN5
ADC0_SW[3:0]
ADC0
ADC1_SW[3:0]
ADC1
ADC0_SW[3:0]
Figure 5. Internal Pin Connections
ADC2
There are two key steps to configure the ADV7181B to correctly
decode the input video.
1. The analog input muxing section must be configured to
correctly route the video from the analog input pins to the
correct set of ADCs.
2. The standard definition processor block, which decodes
the digital data, should be configured to process either
CVBS, YC, or YPrPb.
ANALOG INPUT MUXING
The ADV7181B has an integrated analog muxing section that
allows more than one source of video signal to be connected to
the decoder. Figure 5 outlines the overall structure of the input
muxing provided in the ADV7181B.
A maximum of 6 CVBS inputs can be connected and decoded
by the ADV7181B. As can be seen from the Pin Configuration
and Function Description section, these analog input pins lie in
close proximity to one another. This calls for a careful design of
the PCB layout, for example, ground shielding between all
signals routed through tracks that are physically close together.
It is strongly recommended to connect any unused analog input
pins to AGND to act as a shield.
SETADC_sw_man_en, Manual Input Muxing Enable,
Address C4 [7]
ADC0_sw[3:0], ADC0 mux configuration, Address C3 [3:0]
ADC1_sw[3:0], ADC1 mux configuration, Address C3 [7:4]
ADC2_sw[3:0], ADC2 mux configuration, Address C4 [3:0]
To configure the ADV7181B analog muxing section, the user
must select the analog input (AIN1–AIN6) that is to be
processed by each ADC. SETADC_sw_man_en must be set to 1
to enable the muxing blocks to be configured. The three mux
sections are controlled by the signal buses ADC0/1/2_sw[3:0].
Table 8 explains the control words used.
The input signal that contains the timing information (H/V
syncs) must be processed by ADC0. For example, in YC input
configuration, ADC0 should be connected to the Y channel and
ADC1 to the C channel. When one or more ADCs are not used
to process video, for example, CVBS input, the idle ADCs should
be powered down, (see the ADC Power-Down Control section).
Restrictions on the channel routing are imposed by the analog
signal routing inside the IC; every input pin cannot be routed to
each ADC. Refer to Table 8 for an overview on the routing
capabilities inside the chip.
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