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CN0269 Datasheet, PDF (9/12 Pages) Analog Devices – Devices Connected
Circuit Note
Histogram Test Results
Figure 16 shows the results of a 10,000 sample histogram taken
by shorting the 16 single-ended channels together and connecting
them to the GND of the PCB. Note that the peak-to-peak noise
is approximately 12 LSBs, including the input buffer.
CN-0269
Switching Speed and Settling Time Test Results
The follow figures show the settling performance. The lab test
setup is shown in Figure 18.
SHORTING CABLE
B & K TYPE 1051
SINE GENERATOR
TRIPLE DC POWER SUPPLY
AGILENT E3631A
Figure 16. DC Histogram at 0 V Input, 1 MSPS Sampling Rate, 10,000 Samples
AC Test Results
The ac performance was tested at the system level with the
AD7984 sampling at 300 kSPS with 2.5 V p-p 10.675 kHz input
sine wave signal provided by a Type 1051 B&K sine generator,.
The circuit was sampling continuously on Channel 4, and does
not include the effects of the input buffer. The FFT shows an
SNR = 91.33 dBFS.
1.5V BATTERY STACK
EVAL-CN0269-SDPZ
EVAL-SDP-CB1Z
Figure 18. Switching Speed and Settling Time Lab Test Setup
The CN-0269 evaluation board was configured in the 16-
channel singled input mode, the 8 odd channels were shorted
together, and the 8 even channels were shorted together.
A battery stack was used to generate the different dc input
voltages for low noise and low impedance.
The odd and even channels were connected to different
voltages. The LabVIEWTM software controls the EVAL-SDP-
CB1Z channel-to-channel and switches continually between the
input channels. The switching rate was varied from 100 Hz to
1 MHz in 1 kHz increments. There were 10 samples taken at
each switching rate, and the results averaged. The average value
at the lowest switching rate was used as a reference point. The
error at each different switching rate was calculated by taking
the difference between the 10-sample and the reference value.
The test results are shown in Figure 19 to Figure 23.
In the figures, an error of 2 LSBs corresponds to 17-bit settling,
and an error of 4 LSBs corresponds to 16-bit settling.
Figure 17. FFT with a Kaiser Window (Parameter = 20), 2.5 V p-p 10.675 kHz
Input, 300 kSPS Sampling Rate on CH4 Without Input Buffer
Rev. 0 | Page 9 of 12