cs5317 Cirrus Logic, Inc., cs5317 Datasheet - Page 26

• Manufacturer Part Number: cs5317
• Description: 16-bit, 20 Khz Oversampling A/d Converter
• Manufacturer: Cirrus Logic, Inc.

GENERAL DESCRIPTION
The CDB5317 Evaluation Board is a stand-alone
environment for easy lab evaluation of the
CS5317 Delta-Sigma Analog-to-Digital Converter.
Included on the board is a serial-to-parallel con-
verter. The user can access output data in either
parallel or serial form. When supplied with the
necessary +5 V and -5 V power supplies, a
CLKIN signal, and an analog signal source, the
CDB5317 will provide converted data at the 40
pin header.
SUGGESTED EVALUATION METHOD
An efficient evaluation of the CS5317 using the
CDB5317 may be accomplished as described be-
low.
The following equipment will be required for the
evaluation:
-5V.
CS5317.
the Krohn-Hite Model 4400A "Ultra-Low Distor-
tion Oscillator".
board such as the Metrabyte Model PIO12 "24 Bit
Parallel Digital I/O Interface".
form a Fast Fourier Transform (FFT).
The evaluation board includes filter components
for the on-chip phase locked loop. The compo-
nents are adequate for testing if the CLKIN signal
has little or no phase-jitter. If the CDB5317 board
is being tested as part of a system which generates
a CLKIN which contains jitter, the PLL filter
components may need to be optimized for your
system (see the CS5317 data sheet).
26
The CDB5317 Evaluation Board.
A power supply capable of supplying +5V and
A spectrally pure sine wave generator such as
A PC equipped with a digital data acquisition
A software routine to collect the data and per-
A clock source as the CLKIN signal of the
Set-up for evaluation is straightforward. First de-
cide the operating mode and place the jumper on
the board for the proper selection. Then decide
whether the filter components for the phase
locked loop are adequate or whether they should
be changed for your evaluation. The PLL will
lock on a steady clock input with the filter as it is.
Connect the necessary 5 V (CMOS compatible)
CLKIN signal for the application. Use the sine-
wave generator to supply the analog signal to the
CDB5317. Apply the analog input and CLKIN
signals only when the evaluation board is pow-
ered up. Converted data will then appear at the
header on the CDB5317. The header should be
connected to the digital data acquisition board in
the PC through an IDC 40 pin connector and ca-
ble. The software routine should collect the data
from the CDB5317 and run a standard 1024 point
Fast Fourier Transform (FFT). Such an analysis
results in a plot similar to Figure 1. This plot re-
sulted from using a 1kHz input signal and a
Blackman-Harris window for the FFT.
The signal to noise and signal to total harmonic
distortion characteristics of the CS5317 may be
easily measured in this way. The signal to total
harmonic distortion value for a particular input is
the ratio of the RMS value of the input signal and
the sum of the RMS values of the harmonics
shown in the diagram. The dynamic range of the
CS5317 can be measured by reducing the input
Signal
Amplitude
Relative to
Full Scale
-100dB
-120dB
-20dB
-40dB
-60dB
-80dB
0dB
Figure 1. FFT Plot Example
dc
1 kHz
Input Frequency
CDB5317
Sampling Rate: 19.2 kHz
Full Scale:
S/(N+D): 81.39 dB
DS27DB3
± 2.75 V
9.6 kHz