zxcw6100 Diodes, Inc., zxcw6100 Datasheet - Page 10

• Manufacturer Part Number: zxcw6100
• Description: 24 Bit Stereo Direct Drive Digital Audio Amplifier
• Manufacturer: Diodes, Inc.

Bass
The bass control can be set to a selection of corner
frequencies:
These corner frequencies are stated for a nominal
44.1kHz sampling frequency. If the sampling frequency
is altered then the corner frequency is automatically
adjusted. Once selected then the bass control can be
set to either cut or boost with gain from 0dB up to 15dB
in 1dB steps.
Treble
The treble control can be set to a selection of corner
frequencies:
These corner frequencies are stated for a nominal
44.1kHz sampling frequency. If the sampling frequency
is altered then the corner frequency is automatically
adjusted. Once selected then the treble control can be
set to either cut or boost with gain from 0dB up to 15dB
in 1dB steps.
Master clock
Essential to the performance of the system is the
provision of a low jitter clock to the ZXCW6100 device,
a jitter of less than +/-1ns is required. As well as low
jitter the master clock needs to be a consistent mark to
space ratio. This master clock is generated from the
external audio system, consistency needs to be better
than 3ns with a 33MHz master clock.
The relationship between the master clock and the
word clock provided with the audio data input
determines the device speed and oversampling rate for
the ZTA filters and the Noise shaper/PWM drive. The
master clock is a nominal 33.8688MHz for a 44.1kHz fs
(sampling rate) with 768 times oversampling.
Sampling Rates
The ZXCW6100 device supports a wide range of
sampling rates depending on the media being played.
Typically as follows:
ZXCW6100S28
S E M I C O N D U C T O R S
50Hz
100Hz
1200Hz
4kHz
8kHz
12kHz
Single speed
Dual speed
Quad speed
32kHz, 44.1kHz, 48kHz
88.2kHz, 96kHz
176.4kHz, 192kHz
10
ZTA filters
The ZTA filters use the proprietary ZTA algorithm to
perform up to 48 times digital filtering. The speed
mode of the device selects the oversampling
performed:
In addition to providing state of the art out of band
noise performance, the ZTA filter gives superior
transient resolution, which improves sound stage
imaging, timing, focus and bass definition.
Noise shaper & PWM drive
The noise shaper effectively offers continuous
feedback to the system. It enables removal of any dead
time distortion and enables the drive to the PWM FET
switching. Switching distortions are also removed by
the noise shaper.
The PWM output converts the noise shaper output into
four PWM drive lines per channel. These output lines,
suitably buffered, drive a full MOSFET H bridge. The
output is configured as a bridge tied load. Each of the
four output lines drives N and P channel MOSFET pairs.
The effective PWM frequency is 1MHz, significantly
faster than alternative solutions. This high frequency
allows for greater resolution and enables lower noise
and distortion figures to be achieved. The PWM output
can be utilised either with or without dead time
enabled.
Two different modulation schemes are available,
known as HPWM and RPWM, these two schemes have
different strengths that the user can take advantage of
as they are selectable through the SPI interface.
Accompanying the two PWM schemes is the ability to
select one of two switching frequencies to help attain
the best performance from the PWM scheme and
output stage combination.
HPWM is a conventional digital PWM strategy that is to
be found in current applications. The frequency of
operation is 1.058MHz, derived from 24 times the
44.1kHz sampling frequency.
HPWM provides a lower level of overall RF noise in the
AM band with that noise concentrated on multiples of
the switching frequency. With very careful OP stage
design it is capable of the best measured dynamic
range.
Single speed
Dual speed
Quad speed
ISSUE 2 - FEBRUARY 2004
16 times
8 times
4 times