AK4569 Datasheet, PDF (20/45 Pages) Asahi Kasei Microsystems – 20-Bit Stereo CODEC with IPGA & HP-AMP

ASAHI KASEI
[AK4569]
„ Digital Attenuator
The AK4569 has a channel-independent digital attenuator (256 levels, 0.5dB step). This digital attenuator is placed before
the D/A converter. ATTL/R7-0 bits set the attenuation level (0dB to −127dB or MUTE) for each channel (Table 19). At
DATTC= “1”, ATTL7-0 bits control both Lch and Rch attenuation levels. At DATTC= “0”, ATTL7-0 bits control the
Lch level and ATTR7-0 bits control the Rch level.
The ATS bit sets the transition time between set values of ATT7-0 bits as either 1061/fs or 7424/fs (Table 15). When
ATS= “0”, a soft transition between the set values occurs(1062 levels). It takes 1061/fs (24ms@fs=44.1kHz) from
FFH(0dB) to 00H(MUTE). The ATTs are 00H when the PMDAC bit is “0”. When the PMDAC returns to “1”, the ATTs
fade to their current value. Digital attenuator is independent of the soft mute function.
„ Soft Mute
Soft mute operation is performed in the digital domain. When SMUTE bit goes to “1”, the output signal is attenuated by
−∞ (“0”) via the cycle set by TM1-0 bit (Table 18). When SMUTE bit returns to “0”, the mute is cancelled and the output
attenuation gradually changes to 0dB via the cycle set by TM1-0 bits. If the soft mute is cancelled within the cycle set by
TM1-0 bits after starting the operation, the attenuation is discontinued and returned to 0dB. The soft mute is effective for
changing the signal source without stopping the signal transmission.
SMUTE bit
0dB
Attenuation
TM1-0 bit
(1)
TM1-0 bit
(3)
-∞
GD
GD
(2)
Analog Output
Figure 15. Soft Mute Function
NOTE:
(1) The output signal is attenuated until −∞ (“0”) by the cycle set by TM1-0 bits.
(2) Analog output corresponding to digital input has the group delay (GD).
(3) If the soft mute is cancelled within the cycle set by TM1-0 bits, the attenuation is discontinued and returned to
0dB(the setting value).
MS0292-E-01
- 20 -
2005/07