AD7866 Analog Devices, AD7866 Datasheet - Page 9

• Manufacturer Part Number: AD7866
• Description: Dual 1MSPS, 12-Bit, 2-Channel SAR ADC with Serial Interface
• Manufacturer: Analog Devices

Specifications of AD7866

• Resolution (bits): 12bit
• # Chan: 4
• Sample Rate: 1MSPS
• Interface: Ser,SPI
• Analog Input Type: SE-Uni
• Ain Range: Uni (Vref),Uni (Vref) x 2,Uni 2.5V,Uni 5.0V
• Adc Architecture: SAR
• Pkg Type: SOP

PERFORMANCE CURVES
TPC 1 shows a typical FFT plot for the AD7866 at 1 MHz
sample rate and 300 kHz input frequency. TPC 2 shows the
signal-to-(noise + distortion) ratio performance versus input
frequency for various supply voltages while sampling at 1 MSPS
with an SCLK of 20 MHz.
TPCs 3a to 4b show the power supply rejection ratio versus
AV
conditions. The power supply rejection ratio (PSRR) is defined
as the ratio of the power in the ADC output at full-scale fre-
quency f, to the power of a 100 mV sine wave applied to the
ADC AV
Typical Performance Characteristics
REV. A
DD
supply ripple frequency for the AD7866 under different
–115
–61
–63
–65
–67
–69
–71
–73
–75
–15
–35
–55
–75
–95
DD
10k
0
0
T
4098 POINT FFT
f
f
SNR = 70.31dB
THD = –85.47dB
SFDR = –86.64dB
supply of frequency f
A
SAMPLE
IN
TPC 2. SINAD vs. Input Frequency
= 25 C
= 300kHz
50
TPC 1. Dynamic Performance
PSRR dB
= 1MSPS
100
150
( )
INPUT FREQUENCY – Hz
V
DD
FREQUENCY – kHz
200
= V
=
DRIVE
10 log
100k
250
S
:
V
= 4.75V
DD
300
= V
(
V
Pf Pf
DD
DRIVE
V
= V
350
DD
DRIVE
= 3.6V
= V
S
)
400
DRIVE
= 2.7V
= 5.25V
450
500
1M
–9–
Pf = power at frequency f in ADC output, and Pf
frequency f
peak-to-peak sine wave is coupled onto the AV
digital supply is left unaltered. TPCs 3a and 3b show the PSRR
of the AD7866 when there is no decoupling on the supply, while
TPCs 4a and 4b show the PSRR with decoupling capacitors
of 10 µF and 0.1 µF on the supply.
TPCs 5 and 6 show typical DNL and INL plots for the AD7866.
TPC 7 shows a graph of the total harmonic distortion versus
analog input frequency for various source impedances.
TPC 8 shows a graph of total harmonic distortion versus analog
input frequency for various supply voltages. See the Analog
Input section.
–100
–100
–10
–20
–30
–40
–70
–80
–90
–10
–20
–30
–40
–50
–60
–70
–80
–90
–50
–60
TPC 3a. PSRR vs. Supply Ripple Frequency,
without Supply Decoupling
TPC 3b. PSRR vs. Supply Ripple Frequency,
without Supply Decoupling
0
0
S
1k
1k
coupled onto the ADC AV
100mV p-p SINE WAVE ON AV
2.5V EXT REFERENCE ON D
100mV p-p SINE WAVE ON AV
2.5V EXT REFERENCE ON V
T
T
V
A
A
DD
V
= 25 C
V
= 25 C
DD
DD
= 4.75V
V
= 5.25V
= 2.7V
DD
= 3.6V
AV
AV
DD
DD
10k
10k
V
V
V
DD
RIPPLE FREQUENCY – Hz
RIPPLE FREQUENCY – Hz
DD
DD
= 2.7V
= 5.25V
= 3.6V
V
DD
REF
CAP
= 4.75V
DD
DD
A, D
DD
CAP
100k
100k
supply. Here, a 100 mV
B
DD
AD7866
supply while the
S
= power at
1M
1M