TDA7522

20/23

Figure 5. Delta Sigma Functions

5.10 Decimation filter

This is for Down sampling filter of Diode signals which have been digitized with Oversampling in Analog

stage (TDA7521).

Input Signals are A+C, B+D, E, F diode signals;

Initial sampling frequency

48Fs (2.1168MHz) / 96Fs (4.2336MHz) for 2x, 4x speed

6 bit resolutions from ADC

After Downsampling

2Fs (88.2KHz) / 4Fs (176.4KHz) for 2x, 4x speed

10 bit resolutions into Servo Block

Downsampling ratio

24times.

5.11 PDM/PWM

This is a single end output stage of Tracking, Focusing actuator, Sled and Spindle motor signal using fol-

lowing technic.

Pulse-width modulation (PWM)

Pulse density modulation (PDM)

There are 8 bit Output accuracy.

5.12 SPDIF

This is a decoder to output Audio&Subcode data based on standard format of AES/EBU digital output.

8 times Oversampling filter

FIR

FIR

FIR

x2

x2

x2

Linear

interpolation

32 times OVS

x256 Oversampling

SW by DSP

HW

Fs: 44.1KHz

Fs: 11.28MHz 22bit input

1bit output

2nd

Noise

Shaper

3rd

order

SC filter

Smoothing

filter

TDA7522

TDA7521

Analog section

Digital Section