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7.6.3 Hi-bit IC (PDR-19RW Only)

The PDR-19RW has a Hi-bit IC. It transforms 16-bit audio data

from the encoder into 24-bit audio data.

7.6.4 D/A Converter

The PE8001A is used as the D/A converter (the PDR-509/KU/CA

uses the PCM1716).

The PE8001A can switch the characteristics of digital filters. The

switching is made in accordance with the serial data output from the

mode-control microcomputer. The digital filter settings are switched

depending on the product destination, as shown in the table below:

Types of the Digital Filter Models/Destinations

Normal digital filter

Legato link

(With the PCM1716, switched between normal digital filter and slow

roll off)

"Enhanced multilevel sigma-delta techniques" are employed for the

DAC block. They convert the output from the digital filter block

into an 8-level sigma-delta modulation signal. Their anti-jitter

efficiency of the operation clock is superior to that of the normal 1-

bit DAC.

7.6.5 Analog Audio Output Block

The output from the D/A converter is output via the buffer amplifier,

which has a gain of about 7 dB.

There are two audio-mute circuits. One is a mute circuit controlled

by a microcomputer, and the other is a zero-detection circuit

controlled by the ZERO terminal of the D/A converter.

This ZERO terminal outputs a signal when the audio input to the D/

A converter becomes Infinity or Zero for both channels.

PDR-555RW, PDR-V500, PDR-19RW, PDR-509

PDR-555RW/KU/CA

PDR-V500/KU/CA

PDR-509/KU/CA(using PCM1716)

PDR-555RW/MY

PDR-19RW/KU/CA

PDR-509/MY

7.7 DIGITAL CIRCUITS

7.7.1 Digital Audio Interface Input Block

There are two systems of digital interface input: coaxial and optical.

The coaxial input is sent to IC308 (LC89585, pin 4) via the duty-

ratio adjustment circuit composed of IC313 (TC74HC00AF) and

IC314 (NJM2940M), after its waveform being adjusted by IC305

(TC74HCU04AF).

The optical digital input ( JA301 (GP1F32R) output) is sent to IC308

(LC89585, pin 1) via the duty-ratio adjustment circuit, composed of

IC313 (TC74HC00AF) and IC314 (NJM2940M).

The PDR-509 has no waveform adjustment circuit in the digital input

block.

7.7.2 Sampling Rate Converter

The AD1893JST, the asynchronous type, is used as the sampling

rate converter.

The sampling rate converter is bypassed as for PDR-509 when the

sampling rate of the input is 44.1kHz.

7.7.3 Clock-jitter Suppressor Circuit

(PDR-509 only)

The clock-jitter suppresser circuit of the encoder IC is used to absorb

the jitter from the digital interface receiver when the sampling rate

converter is in through mode.

7.7.4 Data Selector

The DIR block output, the clock-jitter suppressor block output, or

the 384-fs clock input from the XTALIN terminal is output from

the DACCKOUT and ENCCKOUT terminals in accordance with a

signal from the microcomputer.

7.7.5 Digital Fader, Level Meter, Mute

Blocks

The output range of the digital fader block is +17.99 to -66.22 dB.

The level meter interface block provides the data select output and

the fader output. The selected input data are processed to provide

total 16-bit data for L channel and R channel. The level meter

interface block has a zero detection circuit, which outputs to

microcomputer interface block when detecting that the input data to

both channels are all zero.

Muting can be turned on/off for the output from the fader block.

The digital volumes of the PDR-509 also use this block. The variable

range is +12 dB to -48 dB.

7.7.6 Memory Control

The encoder IC can control an external D-RAM (1 or 4 Megabits).

It receives signals from the mute block, the clock-jitter suppressor

block and the encode block.