AK7750 Datasheet, PDF (70/77 Pages) Asahi Kasei Microsystems – Audio DSP with Built-in Hands-Free Phone Features

[ASAHI KASEI]
[AK7750]
(10) DAC Soft Mute Operation
DAC block in the AK7750 includes soft mute circuit.
Soft mute operation is performed at digital domain. When the SMUTE bit goes to “1”, the output signal is
attenuated from 0dB level to -∞ level during the LRCLK cycle time that is specified by SF1 bit and SF0 bit
in CONT5 register plus additional 2LRCLK cycle time(max). When the SMUTE bit is returned to “0”, the
mute is cancelled and the output attenuation gradually changes to 0dB level by the same cycle. If the soft
mute is cancelled before attenuating to -∞ after starting the operation, the attenuation is discontinued and
returned to 0dB by the same cycle. The soft mute is effective when S_RESET is “H” (DAC opeates
normally) External mute circuit is recommended to suppress the pop noise at the reset.
Attenuation value is initialized by INIT_RESET =”L”, not S_RESET =”L”
SMUTE bit
0dB
Attenuation
-∞dB
Analog out
setting value +2LRCLK(max)
setting value +2LRCLK(max)
GD
GD
Soft Mute Operation
SMUTE bit
0dB
Attenuation
-∞dB
setting value +2LRCLK(max)
GD
S_RESET
Analog out
External Mute
Circuit
pop noise
Mute ON
Example of soft mute control@ S_RESET =”H”
setting value +2LRCLK(max)
[MS0296-E-00]
70
2005/03