ak4145 AKM Semiconductor, Inc., ak4145 Datasheet - Page 13

• Manufacturer Part Number: ak4145
• Description: Digital Stereo Btsc Encoder
• Manufacturer: AKM Semiconductor, Inc.

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The AK4145 is designed to be 100% modulation of L+R signal when L=R= 50% (approx. -6dBFS) signal data is input. In
addition to this -6dBFS, the BTSC standard contains the pre-emphasis filter. To prevent the clipping in a BTSC encoder
AK4145, following maximum input levels are recommended. The input data can be attenuated by controlling the Stereo
Volume Control registers (L7-0, R7-0 bits).
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The AK4145 has a stereo digital volume control (DVOL. 256 levels, 0.5dB step, Mute). The L7-0, R7-0 bits control the
gain. The gain ranges from +31.0dB to –96.0dB, or MUTE. When the VOLC bit = “1” (default), the L7-0 bits control gain
for both Lch and Rch. When the VOLC bit = “0”, the L7-0 bits control gain for Lch and R7-0 bits control gain for Rch.
This volume has a soft transition function. When changing levels, transitions are executed with soft changes; thus no
switching noise occurs during these transitions. The transition time of 1 level and all levels are shown in
parallel control mode, volume control is fixed to 0dB.
Rev. 0.3
Input Level to BTSC Encoder
Stereo Volume Control (DVOL)
Frequency[Hz]
20~1000
R7-0
FDH
FDH
3DH
FEH
L7-0
3DH
FEH
3EH
3FH
FFH
13000
3EH
3FH
FFH
00H
01H
00H
01H
2500
5000
8000
4LRCK
:
Table 7. Maximum Input Level to BTSC Encoder
1 Level
:
Table 8. DVOL Transition Time
Table 10. Rch Digital Volume
Table 9. Lch Digital Volume
DVOL Transition Time
0dB to -96dB
768LRCK
MUTE (-∞)
MUTE (-∞)
to BTSC Encoder[dBFS]
- 13 -
+31.0dB
+30.5dB
Maximum Input Level
+31.0dB
+30.5dB
-95.5dB
-96.0dB
-95.5dB
-96.0dB
+0.5dB
+0.5dB
-0.5dB
-0.5dB
Gain
Gain
0dB
0dB
:
:
:
:
-10
-14
-15
-22
-7
+31.0dB to -96dB
1016LRCK
(default)
(default)
Table
[AK4145]
2007/11
8. In