ASAHI KASEI
[AK4319A]
De-emphasis filter
The AK4319A includes the digital de-emphasis filter(tc=50/15us) by IIR filter.This filter corresponds to
three sampling frequencies(32kHz,44.1kHz,48kHz). De-emphasis is enabled by the following two ways.
DEM1 DEM0
Mode
0
0
1
0
1
0
44.1kHz
OFF
48kHz
1
1
32kHz
Table 3 . De-emphasis filter control
Zero detection
After the input data at both channels are continuously zeros for 8192 LRCK cycles or when the muting
period exceeds 8192+1022 LRCK cycles, DZF goes to "H". DZF goes "L" immediately after non zero
data is input or soft mute is released.
Soft mute operation
When SMUTE goes "H", the output signal is attenuated into -∞ during 1022 LRCK cycles. SMUTE is
returned to "L", the mute condition is released and the output attenuation gradually changes to 0dB
during 1022 LRCK cycles. If the soft mute is released within 1022LRCK cycles, the attenuation is
recovered to 0dB with same gradient and cycles.
The soft mute function is effective when changing the signal source without stopping the signal
transmission.
Notes:
1
{
2
{
The output signal is attenuated into -∞ during 1022 LRCK cycles(1022/fs).
Analog output corresponding to digital input have the group delay(GD).
3
{
4
{
If the soft mute is released within 1022 LRCK cycles, the attenuation is recovered to 0dB.
When the input data at both channels are continuously zeros for 8192 LRCK cycles, DZF goes to
"H". DZF goes "L" immediately after non-zero data is input.
Figure 6 . Soft mute and zero detection
M0011-E-01
1998/6
- 11 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
