LC78621E Datasheet, PDF (25/34 Pages) Sanyo Semicon Device – Compact Disc Player DSP

LC78621E
20. CD-ROM Outputs; Pin 42: LRSY, pin 43: CK2, pin 44: ROMXA, pin 45: C2F
Although the LC78621E is initially set up to output audio data from the interpolation circuit MSB first from the
ROMXA pin in synchronization with the LRSY signal, the circuit can be switched to output CD-ROM data by
issuing a CD-ROM XA command. Since this data has not been processed by the interpolation, muting, and other
digital circuits, it is appropriate for input to a CD-ROM encoder LSI. CK2 is a 2.1168 MHz clock, and data is output
on the CK2 falling edge. However, this clock polarity can be inverted by issuing a CK2 polarity inversion command.
C2F is the flag information for the data in 8-bit units. Note that the CD-ROM XA reset command has the same
function as the CONT pin (pin 73).
MSB
LSB
10001000
10001011
11001001
Command
CD-ROM XA
CONT AND CD-ROM XA RESET
CK2 POLARITY INVERSION
LC78621E CD-ROM encoder LSI (LC895XX) interface
RES = low
q
21. Digital Output Circuit; Pin 56: DOUT
This is an output pin for use with a digital audio interface. Data is output in the EIAJ format. This signal has been
processed by the interpolation and muting circuits. This pin has a built-in driver circuit and can directly drive a
transformer.
MSB
LSB
01000010
01000011
01000000
01000001
Command
DOUT ON
DOUT OFF
UBIT ON
UBIT OFF
RES = low
q
q
• The DOUT pin can be locked at the low level by issuing a DOUT OFF command.
• The UBIT information in the DOUT data can be locked at zero by issuing a UBIT OFF command.
• The DOUT data can be switched to data for which interpolation and muting processing have not been performed
by issuing a CD-ROM XA command.
22. AntiShock Mode; Pin 38: ASDACK, pin 39: ASDFIN, pin 40: ASDFIR, pin 41: ASLRCK, pin 42: LRSY, pin 43:
CK2, pin 44: ROMXA, pin 45: C2F
• Antishock mode is a mode in which antishock processing is applied to data that has been output once. That data is
returned and output once again as an audio playback signal. It is also possible to use only the audio playback block
(the attenuator, 8× oversampling digital filter, and one-bit D/A converter circuits) and thus share the audio
playback block with other systems by synchronizing the other system with this LSI’s clock.
Note that de-emphasis on/off switching is controlled by the LC78621E subcode Q playback state.
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