LC78620E Datasheet, PDF (21/34 Pages) Sanyo Semicon Device – Compact Disc Player DSP

LC78620E
12. Level Meter (LVM) Data and Peak Meter (PKM) data readout
MSB
LSB
00101011
00101100
00101101
00101110
Command
PKM SET (LVM reset)
LVM SET (PKM reset)
PKM MASK SET
PKM MASK RESET
RES = low
q
q
• Level meter (LVM)
— The LVM set (2CH) command sets the LC78620E to LVM mode.
— LVM data is a 16-bit word in which the MSB indicates the L/R polarity and the low-order 15 bits are absolute
value data. A one in the MSB indicates left channel data and a zero indicates right channel data.
— LVM data is appended after the 80 bits of SubQ data, and can be read out by applying 96 clock cycles to the
CQCK pin. Each time LVM data is read out the left/right channel state is inverted. Data is held independently
for both the left and right channels. In particular, the largest value that occurs between readouts for each
channel is held.
• Peak meter (PKM)
— The PKM set (2BH) command sets the LC78620E to PKM mode.
— PKM data is a 16-bit word in which the MSB is always zero and the low-order 15 bits are absolute value data.
This functions detects the maximum value that occurs in the data, whichever channel that value occurs in.
— PKM data is read out in the same manner as LVM data. However, data is not updated as a result of the readout
operation.
— The absolute time for PKM mode SubQ data is computed by holding the absolute time (ATIME) detected after
the maximum value occurred and sending that value. (Normal operation uses relative time.)
— It is possible to set the LC78620E to ignore values larger than the already recorded value by issuing the PKM
mask set command, even in PKM mode. This function is cleared by issuing a PKM mask reset command. (This
is used in PK search in a memory track.)
13. Mute Control Circuit
MSB
LSB
00000001
00000010
00000011
Command
MUTE: 0 dB
MUTE: –12 dB
MUTE: –∞ dB
RES = low
q
An attenuation of 12 dB (MUTE –12 dB) or full muting (MUTE ∞ dB) can be applied by issuing the appropriate
command from the table. Since zero-cross muting is used, there is minimal noise associated with this function. Zero
cross is defined for this function as the top seven bits being all ones or all zeros.
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