AK4145 Datasheet, PDF (15/27 Pages) Asahi Kasei Microsystems – Digital BTSC Stereo Encoder

[AK4145]
■ BTSC Stereo/MONO Output Control
The STR bit controls Stereo/MONO output mode. Setting of the STR bit “1” (default) selects BTSC stereo output mode.
Setting of the STR bit “0” selects MONO mode. In parallel control mode, the AK4145 is fixed to stereo mode. The
external pre-emphasis circuit must not be used.
STR bit
1
0
Composite audio output
Stereo mode. outputs BTSC stereo composite
MONO mode, outputs only pre-emphasized (L+R) component.
Table 12. Stereo/MONO Control
(default)
■ Audio Composite Output Volume (DATT)
The AK4145 includes a digital output volume control (DATT) for base band with 256 levels at linear step including
MUTE. This volume control is in front of the DAC and can attenuate the input data from 0dB to –42dB and mute. When
changing levels, transitions are executed in soft changes; thus no switching noise occurs during these transitions. The
transition time of 1 level and all 256 levels is shown in Table 10. In parallel control mode, this volume is fixed to 0dB.
DATT Transition Time
1 Level
255 to 0
4LRCK
1020LRCK
Table 10. DATT Transition Time
■ Video Sync Input
When VCLK bit = “0”(default), the sync separator generates the sync signal using external composite video signal via the
CV27M pin. When VCLK bit = “1”, the 27MHz clock is required through this pin to generate the video sync signal. The
sync signal is used to generate the 15.734kHz pilot tone for BTSC stereo encoding. In parallel control mode, this pin is
fixed to video sync input.
■ Stereo Matrix Control
The AK4145 has the stereo matrix control. The PL3-0 bits control the matrix.
PL3 PL2 PL1 PL0
0
0
0
0
0
0
0
1
0
0
1
0
0
0
1
1
0
1
0
0
0
1
0
1
0
1
1
0
0
1
1
1
1
0
0
0
1
0
0
1
1
0
1
0
1
0
1
1
1
1
0
0
1
1
0
1
1
1
1
0
1
1
1
1
Lch Output
Rch Output
MUTE
MUTE
MUTE
R
MUTE
L
MUTE
(L+R)/2
R
MUTE
R
R
R
L
R
(L+R)/2
L
MUTE
L
R
L
L
L
(L+R)/2
(L+R)/2
(L+R)/2
MUTE
R
(L+R)/2
L
(L+R)/2
(L+R)/2
Table 13. Stereo Matrix Control
Note
MUTE
REVERSE
STEREO
(default)
MONO
MS0982-E-01
- 15 -
2010/09