AK7735EQ Datasheet, PDF (104/142 Pages) Asahi Kasei Microsystems – Dual DSP with 4chADC + 4chDAC + 4chSRC

[AK7735]
2. DAC Soft Mute
The DAC block has a digital soft mute circuit. The soft mute operation is performed at digital domain.
The output signal is attenuated to -∞ in “ATT setting level x ATT transition time” from the current DAC
digital volume setting level by setting DA1MUTE bit or DA2MUTE bit to “1”. When the DA1MUTE bit or
DA2MUTE bit returns to “0”, the mute is cancelled and the output attenuation level gradually changes to
ATT setting level in “ATT setting level x ATT transition time”. If the soft mute is cancelled before
attenuating to -∞ after starting the operation, the attenuation is discontinued and the volume level returns
to original volume setting level by the same cycle. The soft mute is effective for changing the signal
source without stopping the signal transmission.
The attenuation level transition takes 924/fs from 0dB to -∞ and from -∞ to 0dB. Soft mute function is
available when each DAC is in operation. The attenuation value is initialized by setting the PDN pin = “L”.
The DAC1 (DAC2) is reset by setting PMDA1 bit (PMDA2 bit) to “0”. A click noise may occur when reset
the DAC block and releasing the reset. The output signal should be muted externally if the click noise
adversely affects the system performance.
DA1MUTE or DA2MUTE bit
0dB
Attenuation Level
-∞dB
924/fs
GD
924/fs
Group Delay (GD)
Output Image
Soft Mute Operation
Figure 75. DAC Soft Mute Operation
016014707-E-00
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2016/12