SM5847AF datasheet(15/30 Pages) NPC

15 / 30 page

SM5847AF

NIPPON PRECISION CIRCUITS—15

Digital Deemphasis (DEMPL, DEMPR, FSEL1, FSEL2)

Most deemphasis ﬁlters are constructed using analog

circuit techniques. Here, an IIR ﬁlter is employed to

faithfully reproduce the gain and phase characteris-

tics of standard analog deemphasis ﬁlters, corre-

sponding

analog

50µs/15µs

frequency

characteristics. Three sets of ﬁlter coefﬁcients for the

three fs = 32/44.1/48 kHz sampling frequencies are

supported. Deemphasis for other values of fs are not

supported.

Deemphasis ON/OFF (DEMPL, DEMPR)

Deemphasis for the left and right-channel can be

controlled independently.

Filter coefﬁcient select (FSEL1, FSEL2)

Soft Muting (MUTEL, MUTER)

The muting function controls the muting of left and

right-channel independently. Input data continues to

be accepted even when mute is operating.

Mute ON/OFF

When MUTEL (MUTER) goes HIGH, the attenua-

tion changes smoothly from 0 to

−∞ dB. Similarly,

when MUTEL (MUTER) goes LOW, muting is

released and the attenuation changes smoothly from

−∞ to 0 dB. This operation is termed soft muting.

Soft muting takes an interval of approximately

512/fs, or about 11.6 ms when fs = 44.1 kHz.

Mute operation at reset

When RSTN goes LOW, the DOL and DOR outputs

are immediately muted to

−∞ dB. When RSTN goes

HIGH, reset is released and the outputs are immedi-

ately set to 0 dB attenuation.

Note that even when either MUTEL or MUTER or

both are HIGH, the reset operation takes precedence.

Table 1. Deemphasis control

DEMPL

DEMPR

Deemphasis

LO W

Left-channel OFF

HIGH

Left-channel ON

L O W

Right-channel OFF

HIGH

Right-channel ON

Table 2. Deemphasis ﬁlter coefﬁcient select

FSEL1

FSEL2

Sampling frequency (fs)

L O W

44.1 kHz

L O W

HIGH

48 kHz

HIGH

L O W

Prohibited mode

HIGH

32 kHz

Table 3. Mute control

MUTEL

MUTER

Soft muting

LO W

Left-channel OFF

HIGH

Left-channel ON

L O W

Right-channel OFF

HIGH

Right-channel ON

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