SM5906AF datasheet(22/30 Pages) NPC

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NIPPON PRECISION CIRCUITS-22

SM5906AF

Correct data demodulation becomes impossible for

the CD signal processor IC when a disturbance

exceeding the RAM jitter margin occurs. The

YFLAG signal input pin is used to indicate when

such a condition has occurred.

The IC checks the YFLAG input and stops the write

sequence when such a disturbance has occurred,

and then makes FLAG6 active.

The YFLAG check method used changes depend-

ing on the YFLGS flag (85H command).

(see table1)

YFLAG, FLAG6

85H command

FLAG6 set conditions

FLAG6 reset conditions

YFLGS

When YFLAG = LOW

– By status read (90H command)

When YFLAG = HIGH

– When MSON = LOW or after system reset

Table 1. YFLAG signal check method

13.3ms

VWA(x)

VWA(x + 1)

YBLKCK

VWA

VWA latch set

WAQV set

Microcontroller data set

Refer to Microcontroller interface

Values shown are for rate fs. The values are 1/2 those shown at rate 2fs.

Fig 2. YBLKCK and VWA relationship

The VWA is determined according to the YBLKCK

pin and WAQV command. Refer to the timing chart

below.

1.YBLKCK is a 75 Hz clock(HIGH for 136

µs) when

used for normal read mode and it is a 150 Hz

clock when used for double-speed read mode,

synchronized to the CD format block end timing.

On the falling edge of this clock, stored compare-

connect write address WA1 is promoted to WA2

and stored.(see note 1).

2.The microcontroller checks the subcode and, if

confirmed to be correct, generates a WAQV com-

mand (80H).

3.When the WAQV command is received, the previ-

ously latched WA2 is stored as the VWA.

(Note 1) WA1, in VCD and SVC modes, is the

DRAM write address of the last sync data input

before the YBLKCK falling edge. In CDDA mode,

update occurs in the same manner so that WA1 is

updated every 588 data samples.

VWA (valid write address)

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