Datasheet AD7940 (Analog Devices) - 10

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AD7940 TYPICAL PERFORMANCE CHARACTERISTICS
Figure 5 shows a typical FFT plot for the AD7940 at 100 kSPS Figure 7 shows a graph of the total harmonic distortion versus sample rate and 10 kHz input frequency. Figure 6 shows the the analog input frequency for various supply voltages, while signal-to-(noise + distortion) ratio performance versus the Figure 8 shows a graph of the total harmonic distortion versus input frequency for various supply voltages while sampling at the analog input frequency for various source impedances (see 100 kSPS with an SCLK of 2.5 MHz. the Analog Input section). Figure 9 and Figure 10 show the typical INL and DNL plots for the AD7940.
0 110 VDD = 4.75V FSAMPLE = 100kSPS FSAMPLE = 100kSPS –20 TA = 25
°
C FIN = 10kHz 105 SNR = 84.48dB V –40 SINAD = 84.35dB V DD = 3.6V DD = 3V THD = –98.97dB VDD = 2.7V SFDR = –100.84dB 100 –60 VDD = 4.3V –80 95 (dB) THD (dB) –100 V 90 DD = 5.25V V V DD = 4.75V DD = 2.5V –120 85 –140
03305-0-019
–160
03305-0-021
80 0 10k 20k 30k 40k 50k 10 100 FREQUENCY (kHz) INPUT FREQUENCY (kHz)
Figure 5. AD7940 Dynamic Performance at 100 kSPS Figure 7. AD7940 THD vs. Analog Input Frequency for Various Supply Voltages at 100 kSPS
90 110 FSAMPLE = 100kSPS FSAMPLE = 100kSPS TA = 25
°
C TA = 25
°
C 105 VDD = 4.75V V 100 DD = 5.25V VDD = 4.75V 85 RIN = 10
Ω
95 VDD = 4.3V RIN = 50
Ω
V 90 DD = 3.6V RIN = 100
Ω
SINAD (dB) THD (dB) VDD = 3V 80 85 VDD = 2.5V VDD = 2.7V 80 75
03305-0-020
75 RIN = 1000
Ω 03305-0-022
10 100 70 10 100 INPUT FREQUENCY (kHz) INPUT FREQUENCY (kHz)
Figure 6. AD7940 SINAD vs. Analog Input Frequency Figure 8. AD7940 THD vs. Analog Input Frequency for Various Supply Voltages at 100 kSPS for Various Source Impedances Rev. A | Page 9 of 20 Document Outline Table of Contents Specifications1F Timing Specifications Absolute Maximum Ratings ESD Caution Pin Configurations and Function Descriptions Terminology Typical Performance Characteristics Circuit Information Converter Operation Analog Input ADC Transfer Function Typical Connection Diagram Digital Inputs Modes of Operation Normal Mode Power-Down Mode Power vs. Throughput Rate Serial Interface Microprocessor Interfacing AD7940 to TMS320C541 AD7940 to ADSP-218x AD7940 to DSP563xx Application Hints Grounding and Layout Evaluating the AD7940 Performance Outline Dimensions Ordering Guide