LC78621E Datasheet, PDF (24/34 Pages) Sanyo Semicon Device – Compact Disc Player DSP

LC78621E
18. Digital Filter Outputs; Pin 33: LRCKO, pin 34: DFORO, pin 35: DFOLO, pin 36: DACKO
Data for use with an external D/A converter is output MSB first from DFORO and DFOLO in synchronization with
the falling edge of DACKO. These pins are provided so that an external D/A converter can be used if desired.
• Although this output is from 8× oversampling filters for normal-speed playback, 4× oversampling filters are used
in double-speed playback.
19. One-bit D/A Converter
• The LC78621E PWM block outputs a single data value in the range –3 to +3 once every 64fs period. To reduce
carrier noise, this block adopts an output format in which each data switching block is adjusted so that the PWM
output level does not invert. Also, the attenuator block detects 0 data and enters muting mode so that only a 0 value
(a 50% duty signal) is output.
This block outputs a positive phase signal to the LCHP (RCHP) pin and a negative phase signal to the LCHN
(RCHN) pin. High-quality analog signals can be acquired by taking the differences of these two output pairs using
external low-pass filters.
The LC78621E includes built-in suppression resistors in each of the LCHP/N and RCHP/N pins.
• PWM output format
• PWM output example
No. 5223-24/34