SM5878AM datasheet(12/16 Pages) NPC

12 / 16 page

SM5878AM/AV

NIPPON PRECISION CIRCUITS—12

FUNCTIONAL DESCRIPTION

System Clock/Speed Switching (XTI, XTO, CKO, DS)

The system clock on XTI can be set to run at one of

two speeds, 384fs (normal speed) or 192fs (double-

speed), where fs is the input frequency on LRCI. The

speed for CD playback is set by the input level on

DS, as shown in table 1. The system clock should be

ﬁxed at 16.9344 MHz.

Note that the input clock accuracy and signal-to-

noise

ratio

greatly

inﬂuence

the AC

analog

characteristics.

The system clock can be controlled by a crystal

oscillator comprising a crystal connected between

XTI and XTO and the built-in CMOS inverter.

Alternatively, an external system clock can be input

on XTI. As the internal CMOS inverter has a

feedback resistor, the external clock can be AC

coupled to XTI. The system clock is output on CKO.

System Reset (RSTN)

The device should be reset in the following cases.

At power ON

When LRCI and/or the system clock XTI stop, or

other abnormalities occur.

The device is reset by applying a LOW-level pulse on

RSTN. At system reset, the internal arithmetic

operation and output timing counter are synchronized

on the next LRCI rising edge, as shown in ﬁgure 1.

Audio Data Input (DI, BCKI, LRCI)

The digital audio data is input on DI in MSB-ﬁrst, 2s-

complement, 16-bit serial format.

Serial data bits are read into the SIPO register (serial-

to-parallel converter register) on the rising edge of the

bit clock BCKI.

The arithmetic operation and output timing are

independent of the input timing. Accordingly, after a

reset, as long as the clock frequency ratio between

LRCI and the system clock XTI is maintained, phase

differences between LRCI, BCKI and the system

clock XTI do not affect the functional operation. Also,

any jitter present on the data input clock does not

appear as output pulse jitter.

The bit clock frequency on BCKI should be between

32fs and 64fs.

Table 1. System clock select

Parameter

Symbol

LOW

(normal

speed)

HIGH

(double

speed)

XTI input clock

frequency

fXI

(= 1/tXI)

384fs

192fs

CD playback XTI

frequency

fXI

16.9344 MHz

at fs = 44.1

kHz

16.9344 MHz

at fs = 88.2

kHz

CKO output clock

frequency

fCO

384fs

192fs

Internal system

clock period

TSYS

tXI

Figure 1. System reset timing

RSTN

Internal reset

Outputs muted

LRCI

LOW

123

SM5878AM Datasheet(PDF) 12 Page - Nippon Precision Circuits Inc

SM5878AM Datasheet(HTML) 12 Page - Nippon Precision Circuits Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Datasheet Download

Link URL