AK4640_05 AKM [Asahi Kasei Microsystems], AK4640_05 Datasheet - Page 33

• Manufacturer Part Number: AK4640_05
• Description: 16-Bit ?? CODEC with MIC/HP/SPK-AMP
• Manufacturer: AKM [Asahi Kasei Microsystems]

ASAHI KASEI
The AK4640 has a channel-independent digital attenuator (256 levels, 0.5dB step, Mute). The ATTL/R7-0 bits control
the attenuation level of each channel. When the DATTC bit = “1”, the ATTL7-0 bits control both Lch and Rch attenuation
levels. When the DATTC bit = “0”, the ATTL7-0 bits control Lch level and ATTR7-0 bits control Rch level. This
attenuator has a soft transition function. It takes 1061/fs(24ms@fs=44.1kHz) from 00H(0dB) to FFH(MUTE).
Soft mute operation is performed in the digital domain. When the SMUTE bit goes to a “1”, the output signal is attenuated
by −∞ (“0”) during the cycle set by the TM1-0 bits. When the SMUTE bit is returned to “0”, the mute is cancelled and the
output attenuation gradually changes to 0dB during the cycle set of the TM1-0 bits. If the soft mute is cancelled within the
cycle set by the 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 (Figure 22).
The soft mute function is independent of output volume and cascade connected between both functions.
(1) The output signal is attenuated until -∞ (“0”) by the cycle set by the 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 of setting the TM1-0 bits, the attenuation is discounted and returned to
MS0273-E-02
Digital Attenuator
Soft Mute
0dB(the set value).
SM U T E bit
Attenuation
Analog O utput
0dB
-∞
TM 1-0 bit
ATTL/R7-0
(1)
FDH
FEH
FFH
Table 18. DATT Attenuation Table
00H
01H
02H
03H
:
:
Figure 22. Soft Mute Function
G D
MUTE (−∞)
Attenuation
- 33 -
(2)
−126.5dB
−127.0dB
−0.5dB
−1.0dB
−1.5dB
0dB
:
:
TM 1-0 bit
Default
G D
(3)
[AK4640]
2005/04