TDA1305 Philips Semiconductors, TDA1305 Datasheet - Page 8

• Manufacturer Part Number: TDA1305
• Description: Stereo 1fs data input up-sampling filter with bitstream continuous dual DAC BCC-DAC2
• Manufacturer: Philips Semiconductors

Philips Semiconductors
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 s and
15 s. De-emphasis is synchronized to prevent operation
in the middle of a word. The de-emphasis deviation from
ideal 50 s and 15 s de-emphasis is given in Table 4.
Table 2 De-emphasis.
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.
1995 Dec 08
DEEM1
Stereo 1fs data input up-sampling filter with
bitstream continuous dual DAC (BCC-DAC2)
0
0
1
1
DEEM2
0
1
0
1
de-emphasis disabled
de-emphasis for f
de-emphasis for f
de-emphasis for f
CONDITION
s
s
s
= 32 kHz
= 4.1 kHz
= 48 kHz
8
Oversampling filter (normal-speed mode)
In the normal-speed mode the oversampling filter
consists of:
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:
Pass-band ripple and stop-band attenuation for
double-speed are given in Table 3.
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 8f
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 16f
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 4f
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 8f
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s
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Preliminary specification
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TDA1305T