5002B 데이터 시트보기 (PDF) - TDK Corporation
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5002B Datasheet PDF : 23 Pages
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AVPro® 5002B
Dual SCART A/V Switch
SCART AUDIO SWITCHING
The audio inputs are considered to be associated
with the respective video inputs. As a result, the
video selection determines which audio signals will
be switched to a given SCART output. Refer to the
serial port register table for more information. Also
see the audio switching block diagram shown in
Figure 2.
The 5002B provides inputs for the auxiliary audio
source (Aux_Lin/Aux_Rin) and the stereo DAC
associated with the video encoder inputs (Lin/ Rin).
TV AUDIO OPERATION
The audio source for the TV port is selected in
concert with the video source using the three (3)
LSBs of Register 1. The selected audio signals are
input to internal multiplexers that allow the user to
select between mono and stereo output options. Bits
4 and 5 of Register 3 control the stereo/mono
selection according to the following table:
Bit 5
0
0
1
1
Bit 4
0
1
0
1
TV_Lout source
left input
left + right
left input
right input
TV_Rout source
right input
left + right
left input
right input
At power-up, these bits default to 00 putting the
device in the stereo mode. The outputs of these
multiplexers are then passed through a pair of
programmable attenuators that are controlled by the
two (2) MSBs of Register 4. These register bits
provide the following control of the left and right
audio channels:
Bit 7
0
0
1
Bit 6
0
1
x
Left and right channel levels
attenuation = 0 dB
attenuation = 20 dB
Both channels disabled
The output of these attenuators are then summed
with an audio signal created by summing two
additional audio inputs. These additional audio
inputs are labeled Audio1 and Audio2 on the block
diagram. The purpose of these pins is to allow
externally generated tones to be mixed with the TV
audio signal source.
The state of these two inputs is controlled by Bits 3-
5 of Register 4. At power-up reset, Bit 3 is set to a
high level (1) which disables the Audio1 input.
Setting this bit low (0) enables the input. The Audio2
input passes through a programmable attenuator
prior to being summed with the Audio1 input. Bits 4
and 5 of Register 4 control the level of Audio2
according to the following table:
Bit 5
0
0
1
Bit 4
0
1
x
Audio2 Mode
Audio 2 level = 0 dB attenuation
Audio 2 level = 20 dB attenuation
Audio 2 input disabled
At power-up, Bits 4 and 5 are set high (11) so that
the input is disabled. The sum of the Audio1 and
Audio2 signals is then internally summed with each
of the left and right TV audio signals.
Volume Control: The resulting left and right TV
audio channels are then passed through a volume
control circuit. The lower 6-bits in serial port Register
0 set a programmable attenuation level. The
attenuation is linear at 1 dB per step with a setting of
xx000000 producing 0 dB attenuation and a setting
of xx011111 producing 31 dB of attenuation.
TV SCART Audio Outputs: The first pair of signals
is labeled TV_Lout and TV_Rout on the block
diagram. TV_Lout and TV_Rout are typically used to
drive the TV SCART audio pins. These outputs also
have an internal multiplexer that allows the user to
select TV audio either before or after the internal
volume control function. When Bit 0 in Register 4 is
set low (0), the volume control is used. When this bit
is set high (1), the volume control is bypassed. The
power-up default state is volume control active.
TV Audio Line Outputs: The second pair of signals
is labeled Lout and Rout on the block diagram. Lout
and Rout are standard line outputs. The Lout/Rout
outputs have an internal multiplexer that allows the
user to select TV audio either before or after the
internal volume control function. When Bit 1 in
Register 4 is set low (0), the volume control is used.
When this bit is set high (1), the volume control is
bypassed. The power-up default state is volume
control active.
RF Mono Output: The Lin and Rin input signals are
summed internally to generate a mono audio signal
for an external RF modulator. This output is labeled
Mod_mono. This mono signal can also be mixed
with the Audio1 and Audio2. The switching of the
Audio1 and Audio2 signals on this pin is controlled
by the same bits that control the TV audio outputs.
The internal summing circuit is before the volume
control mux so the Mod_mono output level cannot
be adjusted.
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