AK4566 Datasheet, PDF (20/45 Pages) Asahi Kasei Microsystems – 20bit Stereo CODEC with built-in IPGA & HP-AMP

ASAHI KASEI
AKM CONFIDENTIAL
[AK4566]
n Digital Attenuator
The AK4566 has channel-independent digital attenuator (256 levels, 0.5dB step). This digital attenuator is placed before
D/A converter. ATTL/R7-0 bits set the attenuation level (0dB to -127dB or MUTE) of each channel (Table 19). At
DATTC= “1”, ATTL7-0 bits control both Lch and Rch attenuation level. At DATTC= “0”, ATTL7-0 bits control Lch
level and ATTR7-0 bits control Rch level.
ATS bit set the transition time between set values of ATT7-0 bits as either 1061/fs or 7424/fs (Table 15). At ATS= “0”, the
transition between set values is soft transition of 1062 levels. It takes 1061/fs (24ms@fs=44.1kHz) from FFH(0dB) to
00H(MUTE). The ATTs are 00H when PMDAC bit is “0”. When PMDAC returns to “1”, the ATTs fade to their current
value. Digital attenuator is independent of soft mute function.
n 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 have 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).
REV 0.5
- 20 -
2002/2