ak4145 AKM Semiconductor, Inc., ak4145 Datasheet - Page 14

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

■
A digital de-emphasis filter is built-in (tc = 50/15µs). Setting the DEM bit “1” enables the digital de-emphasis filter. In
parallel control mode, the de-emphasis filter is always “OFF”
■
When the SMUTE bit is set to “H”, the output signal is attenuated from the volume level to -∞dB during 772 LRCK
cycles when the volume level is 0dB. When the SMUTE bit returns to “0”, the mute is cancelled and the attenuation
gradually changes to the volume level. If the soft mute is cancelled before attenuated to the mute state after starting the
operation, the attenuation is discontinued and returned to volume level by the same cycles. The soft mute is effective for
changing the signal source without stopping the signal transmission. In parallel control mode, the soft mute function is not
available.
Notes:
Rev. 0.3
(1) Transition time. 772 LRCK cycles (772/fs) when the volume level is 0dB.
(2) If the soft mute is cancelled before attenuating to -∞ after starting the operation, the attenuation is discontinued
De-emphasis Filter
Soft Mute Operation
Gain (at the input of
SMUTE bit
and returned to the volume level by the same number of clock cycles.
encoder block)
Volume level
-∞
dB
DEM bit
1
0
Table 11. De-emphasis Filter Control
(1)
Figure 6. Soft Mute
De-emphasis Filter
- 14 -
OFF
ON
(default)
(1)
(2)
[AK4145]
2007/11