SM5906AF datasheet(21/30 Pages) NPC

21 / 30 page

NIPPON PRECISION CIRCUITS-21

SM5906AF

Shock-proof mode is the mode that realizes shock-

proof operation using external DRAM. Shock-proof

mode is invoked by setting MSON=H in microcon-

troller command 80H.

This mode comprises the following 3 sequences.

Shock-proof operation overview

– Write sequence

1. Input data from a signal processor IC is read in.

2. Data read in is written to external DRAM in the

sequence left-channel, (C2PO), and right-channel.

(C2PO) is omitted in CDDA mode.

– Read sequence

1. Data written to external DRAM is read out at fs

rate (rate 2fs in SVC mode).

2. Data is output in sync with the 24-bit bit clock

(ZSCK).

– Compare-connect sequence

1. Encoding immediately stops when either external

buffer RAM overflows or when a CD read error

occurs due to shock vibrations.

2. Then, using microcontroller command 80H, the

compare-connect start command is executed

and compare-connect sequence starts.

3. Compares data re-read from the CD with the pro-

cessed final valid data stored in RAM (confirms

its correctness).

4. As soon as the comparison detects conforming

data, compare-connect sequence stops and

encode sequence re-starts, connecting the data

directly behind previous valid data.

RAM addresses

The SM5906AF uses 4M or 16M DRAMs as exter-

nal buffers.

Three kinds of addresses are used for external

RAM control.

WA (write address)

RA (read address)

VWA (valid write address)

Among these, VWA is the write address for con-

forming data whose validity has been confirmed.

Determination of the correctness of data read from

the CD is delayed relative to the write processing,

so VWA is always delayed relative to WA.

The region available for valid data is the area

between VWA-RA.

Fig 1. RAM addresses

VWA

Valid data

area

SM5906AF 数据表(PDF) 21 Page - Nippon Precision Circuits Inc

SM5906AF 数据表(HTML) 21 Page - Nippon Precision Circuits Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

数据表下载