CS5371-BSZR Cirrus Logic Inc, CS5371-BSZR Datasheet - Page 9

• Manufacturer Part Number: CS5371-BSZR
• Description: IC MODULATOR LP/HP 1CH 24-SSOP
• Manufacturer: Cirrus Logic Inc
• Type: Modulatorr

Specifications of CS5371-BSZR

• Sampling Rate (per Second): 512k
• Data Interface: Serial
• Voltage Supply Source: Analog and Digital, Dual ±
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-SSOP
• For Use With: 598-1778 - EVALUATION BOARD FOR CS5376
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Supply: -
• Resolution (bits): -

3. MODULATOR PERFORMANCE
Figures 4 and 5 illustrate the spectral performance
of the CS5371/72 modulators when combined with
the CS5376A or CS5378 digital filter. The plots
were created from ten averaged 1024 point FFTs.
3.1.
Figure 4 illustrates the full-scale signal perfor-
mance of the CS5371/72 modulators and digital fil-
ter using a 31.25 Hz input signal and a 1000 SPS
output word rate. The outstanding full-scale signal
characteristics of the CS5371/72 modulators are
shown, with no harmonic components exceeding -
120 dB. Analysis of this data set yields a signal-to-
noise ratio (SNR) of 124.0 dB and a signal-to-dis-
tortion ratio (SDR) of 119.0 dB. Note that the full-
scale signal peak in Figure 4 shows a slightly re-
duced amplitude due to spectral smearing associ-
ated with the FFT windowing function, and is a
purely digital phenomenon.
3.2.
Figure 5 illustrates the noise performance of the
CS5371/72 modulators and digital filter using a
31.25 Hz -24 dB input signal at a 1000 SPS output
word rate. The outstanding noise characteristics of
the CS5371/72 modulators are shown, with the av-
eraged noise components consistently below the
-150 dB level. Analysis of this data set yields a dy-
namic range of 124.7 dB. Note that the 0.7 dB
DS255F3
-100
-120
-140
-160
-180
-200
-20
-40
-60
-80
0
0
Figure 4. 1024 Point FFT plot with a 31.25 Hz
Full-scale Signal Performance
Noise Performance
50
input at Full-scale, ten averages
100
150
200
250
Hz
300
350
S/N = 124.0 dB
S/D = 119.0 dB
400
450
500
variation between the signal-to-noise calculation in
Figure 4 and the dynamic range calculation in Fig-
ure 5 is not modulator dependent and results from
jitter in the test signal generator when producing a
full-scale output, as evidenced by the skirt sur-
rounding the signal peak below the -140 dB level in
Figure 4.
4. SIGNAL INPUTS
The CS5371/72 modulators use a switched capac-
itor architecture for the analog signal inputs, which
has increased jitter tolerance compared with con-
tinuous time signal input stages.
4.1.
The analog signal inputs are differential and use
four pins: INR+, INR-, INF+, and INF-. Two inputs,
INR+ and INF+, are connected to the positive half
of the differential signal, while two inputs, INR- and
INF-, are connected to the negative half. The INR+
and INR- pins are switched capacitor ‘rough
charge’ inputs that pre-charge the internal sam-
pling capacitor before it is connected to the INF+
and INF- fine input pins.
The full-scale analog signal span is defined by the
voltage applied across the VREF+ and VREF-
pins. A 2.5 volt reference input sets full-scale sig-
nals as 5 volts peak-to-peak, fully differential. Dif-
ferential inputs increase the dynamic range of
-100
-120
-140
-160
-180
-200
-20
-40
-60
-80
0
0
Figure 5. 1024 Point FFT plot with a 31.25 Hz
Differential Inputs - INR+/-, INF+/-
50
input at -24 dB, ten averages
100
150
200
Hz
CS5371 CS5372
250
Dynamic Range = 124.7 dB
300
350
400
450
500
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