UDA1341TS Просмотр технического описания (PDF) - NXP Semiconductors.

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UDA1341TS

Economy audio CODEC for MiniDisc (MD) home stereo and portable applications

NXP Semiconductors. 

NXP Semiconductors

Economy audio CODEC for MiniDisc (MD)

home stereo and portable applications

Product specification

UDA1341TS

7.9 Decimation filter (ADC)

The decimation from 128fs is performed in two stages.

The first stage realizes 3rd order

s----i-n-----x-

x

characteristic,

decimating by 16. The second stage consists of

3 half-band filters, each decimating by a factor of 2.

Table 2 Decimation filter characteristics

ITEM

Passband ripple

Stop band

Dynamic range

Overall gain

CONDITIONS

0 to 0.45fs

>0.55fs

0 to 0.45fs

input channel 1;

0 dB input

VALUE

(dB)

±0.05

−60

108

−1.16

7.10 Overload detection (ADC)

This name is convenient but a little inaccurate. In practice

the output is used to indicate whenever that output data, in

either the left or right channel, is bigger than −1 dB (actual

figure is −1.16 dB) of the maximum possible digital swing.

If this condition is detected the OVERFL output is forced

HIGH for at least 512fs cycles (11.6 ms at fs = 44.1 kHz).

This time-out is reset for each infringement.

7.11 Mute (ADC)

On recovery from power-down or switching on of the

system clock, the serial data output on pin DATAO is held

at LOW level until valid data is available from the

decimation filter. This time depends on whether the

DC-cancellation filter is selected:

• DC cancel off:

t

=

1----0---2----4-

fs

;

t

=

23.2

ms

at

fs

=

44.1

kHz

• DC cancel on:

t

=

1----2---2----8---8--

fs

;

t

=

279

ms

at

fs

=

44.1

kHz.

7.12 Interpolation filter (DAC)

The digital filter interpolates from 1fs to 128fs by means of

a cascade of a recursive filter and a Finite Impulse

Response (FIR) filter.

Table 3 Interpolation filter characteristics

ITEM

Passband ripple

Stop band

Dynamic range

CONDITIONS

0 to 0.45fs

>0.55fs

0 to 0.45fs

VALUE

(dB)

±0.03

−50

108

7.13 Peak detector

In the playback path a peak level detector is build in.

The position of the peak detection can be set via the

L3-interface to either before or after the sound features.

The peak level detector is implemented as a peak-hold

detector, which means that the highest sound level is hold

until the peak level is read out via the L3-interface. After

read-out the peak level registers are reset.

7.14 Quick mute

A hard mute can be activated via the static pin QMUTE.

When QMUTE is set HIGH, the output signal is instantly

muted to zero. Setting QMUTE to LOW, the mute is

instantly de-activated.

7.15 Noise shaper (DAC)

The 3rd-order noise shaper operates at 128fs. It shifts

in-band quantization noise to frequencies well above the

audio band. This noise shaping technique allows for high

signal-to-noise ratios. The noise shaper output is

converted into an analog signal using a filter stream

digital-to-analog converter.

2002 May 16

8

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