TDA1305T View Datasheet(PDF) - Philips Electronics

Part Name

Description

Manufacturer

TDA1305T

Stereo 1fs data input up-sampling filter with bitstream continuous dual DAC (BCC-DAC2)

Philips Electronics 

Philips Semiconductors

Stereo 1fs data input up-sampling filter with

bitstream continuous dual DAC (BCC-DAC2)

Preliminary specification

TDA1305T

Mute

Soft mute is controlled by the MUSB at pin 9. When the

input is active LOW the value of the samples is decreased

smoothly to zero following a cosine curve. To step down

the value of the data 32 coefficients are used, each one

being used 31 times before stepping onto the next. When

MUTE is released (pin 19 = HIGH), the samples are

returned to the full level again following a cosine curve with

the same coefficients being used in the reverse order.

Mute is synchronized to prevent operation in the middle of

a word.

De-emphasis

A digital de-emphasis is implemented for three sample

rates (32, 44.1 and 48 kHz). By selecting DEEM1 and

DEEM2 de-emphasis can be applied by means of a FIR

filter. Time constants of the de-emphasis are 50 µs and

15 µs. De-emphasis is synchronized to prevent operation

in the middle of a word. The de-emphasis deviation from

ideal 50 µs and 15 µs de-emphasis is given in Table 4.

Table 2 De-emphasis.

DEEM1

0

0

1

1

DEEM2

0

1

0

1

CONDITION

de-emphasis disabled

de-emphasis for fs = 32 kHz

de-emphasis for fs = 4.1 kHz

de-emphasis for fs = 48 kHz

Attenuation

Attenuation is controlled by the ATSB input (pin 21). When

the input is active LOW the sample is multiplied by a

coefficient that provides 12 dB attenuation. If the input is

HIGH the multiplication factor is 1. Attenuation is

synchronized to prevent operation in the middle of a word.

Double-speed mode

Double speed is controlled by the DSMB input (pin 20).

When the input is active LOW the device operates in the

double-speed mode.

Oversampling filter (normal-speed mode)

In the normal-speed mode the oversampling filter

consists of:

• A 91st order half-band low-pass FIR filter which

increases the oversampling rate from 1 time to 2 times.

• A 23rd order quarter band low-pass FIR filter which

increases the oversampling rate from 2 times to 8 times.

• A linear interpolation section which increases the

oversampling rate to 16 times. This removes the

spectral components around 8fs.

• A sample-and-hold section which provides another

6 times oversampling to 96 times. The zero-order hold

characteristic of this sample-and-hold section plus the

1st order analog filtering remove the spectral

components around 16fs.

Pass-band ripple and stop-band attenuation for

normal-speed are given in Table 3.

Oversampling filter (double-speed mode)

In the double-speed mode the oversampling filter

consists of:

• A 51st order half-band low-pass FIR filter which

increases the oversampling rate from 1 time to 2 times.

• A 7th order half-band low-pass FIR filter which

increases the oversampling rate from 2 times to 4 times.

• A linear interpolation section which increases the

oversampling rate to 8 times. This removes the spectral

components around 4fs.

• A sample-and-hold section which provides another

6 times oversampling to 48 times. The zero-order hold

characteristic of this sample-and-hold section plus the

1st order analog filtering remove the spectral

components around 8fs.

Pass-band ripple and stop-band attenuation for

double-speed are given in Table 3.

1995 Dec 08

8

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