SM5878AM datasheet(14/16 Pages) NPC

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SM5878AM/AV

NIPPON PRECISION CIRCUITS—14

Soft Mute (SMUTE)

Soft mute mode is selected when MODE is HIGH.

The up/down counter is switched to internal clock

drive, and soft mute operation is controlled by

MUTE only.

When MUTE goes HIGH, the up/down counter

counts down. The total time to go from 0 to

maximum mute is 1024/fs. This corresponds to

approximately 23.2 ms at fs = 44.1 kHz.

When MUTE is LOW, soft mute is released. The

attenuation counter output counts up, increasing the

gain. The time taken to return to 0 dB is also 1024/fs.

Soft

mute

operation

shown

ﬁgure

Upon system initialization or when MODE changes

state, mute is released, which corresponds to the

maximum gain of 0 dB.

Inﬁnity-Zero (MUTEO)

The

SM5878AM/AV

outputs

inﬁnity-zero

detection

output

signal

under

the

following

circumstances.

From immediately after a reset input on RSTN

until the initialization cycle ﬁnishes and the ﬁrst

data cycle occurs.

When an inﬁnity-zero occurs in the input data.

When an inﬁnity-zero is detected, a period of 214

× (1/fs) ≈ 0.37 seconds takes place before

MUTEO goes HIGH.

TIMING DIAGRAMS

Input Timing (DI, BCKI, LRCI)

Figure 2. Soft mute operation example

Gain

MUTE

1024/fs

0 dB

–

Figure 3. MUTEO output timing

LRCI

RSTN

MUTEO

2 /fs

Signal

No Signal

Initialize

BCKI

(64fs max)

LRCI

16 bits

1/fs

Left channel

Right channel

MSB

LSB

MSB

LSB

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