Datasheet
0
20
40
60
80
100
120
140
160
180
200
-
-
-
-
-
-
-
-
-
-
2.0
Amplitude(dB)
NormalizedFrequency(f )
S
0 0.5 1.0
1.5
DSM_Dual
DSM_Single
DF_Single
DF_Dual
0
20
40
60
80
100
120
140
160
180
200
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2.0
Amplitude(dB)
NormalizedFrequency(f )
S
0 0.5 1.0
1.5
DSM_Dual
DSM_Single
DSM_Quad
DF_Dual
DF_Single
DF_Quad
PCM3168A
PCM3168A-Q1
www.ti.com
......................................................................................................................................................................................... SBAS452 – SEPTEMBER 2008
oversampling frequency of x64; this mode is supported for sampling frequencies less than 100 kHz. In quad rate
mode, the DAC operates at an oversampling frequency of x32. The sampling mode is automatically selected
according to the ratio of system clock frequency and sampling frequency by default (for example, single rate for
512 f
S
and 768 f
S
, dual rate for 256 f
S
and 384 f
S
, and quad rate for 128 f
S
and 192 f
S
), but manual selection is
also possible for specified combinations through the serial mode control resistor.
Table 5 and Figure 31 show the relation between the oversampling rate (OSR) of the Δ Σ modulator, noise-free
shaped bandwidth, and each sampling mode setting for ADC operation. Table 6 and Figure 32 describe the
relation between the oversampling rate of the digital filter and Δ Σ modulator, noise-free shaped bandwidth, and
each sampling mode setting for DAC operation.
Table 5. ADC Modulator OSR and Noise-Free Shaped Bandwidthfor Each Sampling Mode
NOISE-FREE SHAPED BANDWIDTH (kHz)
SAMPLING MODE SYSTEM CLOCK RATE
REGISTER SETTING (f
S
) f
S
= 48 kHz f
S
= 96 kHz MODULATOR OSR
512, 768 40 N/A x128
Auto
256, 384 20 40 x64
512, 768 40 N/A x128
Single
256, 384 40 N/A x128
Dual 256, 384 20 40 x64
Table 6. DAC Digital Filter OSR, Modulator OSR, and Noise-Free Shaped Bandwidth
for Each Sampling Mode
NOISE-FREE SHAPED
BANDWIDTH
SAMPLING MODE SYSTEM CLOCK f
S
= 48 f
S
= 96 f
S
= 192
REGISTER SETTING RATE (f
S
) kHz kHz kHz DIGITAL FILTER OSR MODULATOR OSR
512, 768 40 N/A N/A x8 x128
Auto 256, 384 20 40 N/A x8 x64
128, 192
(1) (2)
10 20 40 x4 x32
512, 768 40 N/A N/A x8 x128
Single 256, 384 40 N/A N/A x8 x128
128, 192
(1) (2)
20 N/A N/A x4 x64
256, 384 20 40 N/A x8 x64
Dual
128, 192
(1) (2)
20 40 N/A x4 x64
Quad 128, 192
(1) (2)
10 20 40 x4 x32
(1) Supported only by DAC operation.
(2) Quad mode filter characteristic is applied.
Figure 31. ADC Δ Σ Modulator and Digital Filter Figure 32. DAC Δ Σ Modulator and Digital Filter
Characteristic Characteristic
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