ADAV801ASTZ Analog Devices Inc, ADAV801ASTZ Datasheet - Page 19

• Manufacturer Part Number: ADAV801ASTZ
• Description: IC CODEC AUDIO R-DVD 3.3V 64LQFP
• Manufacturer: Analog Devices Inc
• Type: Audio Codecr

Specifications of ADAV801ASTZ

• Data Interface: Serial
• Resolution (bits): 24 b
• Number Of Adcs / Dacs: 2 / 2
• Sigma Delta: No
• Dynamic Range, Adcs / Dacs (db) Typ: 102 / 101
• Voltage - Supply, Analog: 3 V ~ 3.6 V
• Voltage - Supply, Digital: 3 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 64-LQFP
• Audio Codec Type: Stereo
• No. Of Adcs: 2
• No. Of Dacs: 2
• No. Of Input Channels: 2
• No. Of Output Channels: 2
• Adc / Dac Resolution: 24bit
• Adcs / Dacs Signal To Noise Ratio: 102dB
• Single Supply Voltage (typ): 3.3V
• Single Supply Voltage (min): 3V
• Single Supply Voltage (max): 3.6V
• Package Type: LQFP
• Adc/dac Resolution: 24b
• Interface Type: Serial (SPI)
• Mounting: Surface Mount
• Number Of Adc's: 2
• Number Of Dac's: 2
• Operating Supply Voltage (max): 3.6V
• Operating Supply Voltage (min): 3V
• Operating Supply Voltage (typ): 3.3V
• Operating Temperature (max): 85C
• Operating Temperature (min): -40C
• Pin Count: 64
• Power Supply Type: Analog/Digital
• Sample Rate: 96KSPS
• Screening Level: Industrial
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: EVAL-ADAV801EBZ - BOARD EVALUATION FOR ADAV801
• Lead Free Status / Rohs Status: Compliant

SAMPLE RATE CONVERTER (SRC) FUNCTIONAL
OVERVIEW
During asynchronous sample rate conversion, data can be
converted at the same sample rate or at different sample rates.
The simplest approach to an asynchronous sample rate
conversion is to use a zero-order hold between the two
samplers, as shown in Figure 29. In an asynchronous system, T2
is never equal to T1, nor is the ratio between T2 and T1
rational. As a result, samples at f
producing an error in the resampling process.
The frequency domain shows the wide side lobes that result
from this error when the sampling of f
the attenuated images from the sin(x)/x nature of the zero-order
hold. The images at f
hold are infinitely attenuated. Because the ratio of T2 to T1 is an
irrational number, the error resulting from the resampling at
f
reduced, however, through interpolation of the input data at
f
conceptually interpolated by a factor of 2
Conceptual High Interpolation Model
Interpolation of the input data by a factor of 2
(2
both the time domain and the frequency domain of interpolation
by a factor of 2
steps of zero-stuffing (2
f
digital low-pass filter to suppress the images. In the time
domain, it can be seen that f
sample from the zero-order hold, as opposed to the nearest f
sample in the case of no interpolation. This significantly
reduces the resampling error.
S_OUT
S_IN
S_IN
20
FREQUENCY RESPONSE OF
WITH ZERO-ORDER HOLD SPECTRUM
Figure 29. Zero-Order Hold Used by f
. Therefore, the sample rate converter in the ADAV801 is
− 1) samples between each f
sample and convolving this interpolated signal with a
IN
can never be eliminated. The error can be significantly
f
S_IN
= 1/T1
SPECTRUM OF ZERO-ORDER HOLD OUTPUT
20
. Conceptually, interpolation by 2
SPECTRUM OF
SIN(X)/X OF ZERO-ORDER HOLD
S_IN
ORIGINAL SIGNAL
SAMPLED AT
20
(dc signal images) of the zero-order
f
ZERO-ORDER
f
S_OUT
S_OUT
− 1) number of samples between each
HOLD
S_OUT
f
S_OUT
CONVOLVED
S_IN
S_OUT
selects the closest f
f
S_ OUT
S_IN
SAMPLING
sample. Figure 30 shows
are repeated or dropped,
to Resample Data from f
S_OUT
f
S_OUT
20
.
is convolved with
= 1/T2
20
involves placing
20
2 ×
involves the
OUT
S_IN
f
S_OUT
× 2
S_IN
20
S_IN
Rev. A | Page 19 of 60
In the frequency domain shown in Figure 31, the interpolation
expands the frequency axis of the zero-order hold. The images
from the interpolation can be sufficiently attenuated by a good
low-pass filter. The images from the zero-order hold are now
pushed by a factor of 2
of the zero-order hold, which is f
zero-order hold are the determining factor for the fidelity of the
output at f
IN
IN
Figure 31. Frequency Domain of the Interpolation and Resampling
f
f
S_IN
S_IN
FREQUENCY DOMAIN OF THE INTERPOLATION
FREQUENCY DOMAIN OF
FREQUENCY DOMAIN
AFTER RESAMPLING
FREQUENCY DOMAIN OF SAMPLES AT
S_OUT
SIN(X)/X OF ZERO-ORDER HOLD
TIME DOMAIN OF
TIME DOMAIN OUTPUT OF THE LOW-PASS FILTER
TIME DOMAIN OF
TIME DOMAIN OF THE ZERO-ORDER HOLD OUTPUT
INTERPOLATE
INTERPOLATE
.
BY N
BY N
Figure 30. SRC Time Domain
20
closer to the infinite attenuation point
f
f
S_IN
S_OUT
LOW-PASS
LOW-PASS
f
S_OUT
FILTER
FILTER
SAMPLES
RESAMPLING
S_IN
RESAMPLING
× 2
2
f
20
ZERO-ORDER
S_IN
ZERO-ORDER
20
. The images at the
×
HOLD
f
HOLD
S_IN
2
2
20
f
20
S_IN
×
×
f
f
S_IN
ADAV801
S_IN
f
f
S_OUT
S_OUT
OUT
OUT