–2–
REV. 0
AD7720–SPECIFICATIONS1
(AVDD = +5 V
5%; DVDD = +5 V
5%; AGND = DGND = 0 V, fMCLK = 12.5 MHz,
REF2 = +2.5 V; TA = TMIN to TMIN, unless otherwise noted)
Parameter
B Version
Units
Test Conditions/Comments
STATIC PERFORMANCE
When Tested with Ideal FIR Filter as in Figure 1
Resolution
16
Bits
Differential Nonlinearity
±1
LSB max
Guaranteed Monotonic
Integral Nonlinearity
±2
LSB typ
Precalibration Offset Error
±6
mV typ
Precalibration Gain Error
2
±0.6
% FSR typ
Postcalibration Offset Error
3
±1.5
mV typ
Postcalibration Gain Error
2, 3
±0.3
% FSR typ
Offset Error Drift
±1
LSB/
°C typ
Gain Error Drift
REF2 Is an Ideal Reference, REF1 = AGND
Unipolar Mode
±1
LSB/
°C typ
Bipolar Mode
±0.5
LSB/
°C typ
ANALOG INPUTS
Signal Input Span (VIN(+) – VIN(–))
Bipolar Mode
±V
REF2/2
V max
BIP = VIH
Unipolar Mode
0 to VREF2
V max
BIP = VIL
Maximum Input Voltage
AVDD
V
Minimum Input Voltage
0
V
Input Sampling Capacitance
2
pF typ
Input Sampling Rate
2 fMCLK
MHz
Differential Input Impedance
10
9/(8 f
MCLK)k
typ
REFERENCE INPUTS
REF1 Output Voltage
2.32 to 2.62
V min/max
REF1 Output Voltage Drift
60
ppm/
°C typ
REF1 Output Impedance
3
k
typ
Reference Buffer Offset Voltage
±12
mV max
Offset Between REF1 and REF2
Using Internal Reference
REF2 Output Voltage
2.32 to 2.62
V min/max
REF2 Output Voltage Drift
60
ppm/
°C typ
Using External Reference
REF1 = AGND
REF2 Input Impedance
10
9/(16 f
MCLK)k
typ
External Reference Voltage Range
2.32 to 2.62
V min/max
Applied to REF1 or REF2
DYNAMIC SPECIFICATIONS
4
When Tested with Ideal FIR Filter as in Figure 1
Bipolar Mode
BIP = VIH, VCM = 2.5 V, VIN(+) = VIN(–) = 1.25 V p-p
or VIN(–) = 1.25 V, VIN(+) = 0 V to 2.5 V
Signal to (Noise + Distortion)
5
90
dB typ
Input BW = 0 kHz–90.625 kHz
86/84.5
dB min
Total Harmonic Distortion
5
–90/–88
dB max
Input BW = 0 kHz–90.625 kHz
Spurious Free Dynamic Range
–90
dB max
Input BW = 0 kHz–90.625 kHz
Unipolar Mode
BIP = VIL, VIN(–) = 0 V, VIN(+) = 0 V to 2.5 V
Signal to (Noise + Distortion)
5
88
dB typ
Input BW = 0 kHz–90.625 kHz
84.5/83
dB min
Total Harmonic Distortion
5
–89/–87
dB max
Input BW = 0 kHz–97.65 kHz
Spurious Free Dynamic Range
–90
dB max
Input BW = 0 kHz–97.65 kHz
Intermodulation Distortion
–93
dB typ
AC CMRR
96
dB typ
VIN(+) = VIN(–) = 2.5 V p-p, VCM = 1.25 V to
3.75 V, 20 kHz
Overall Digital Filter Response
See Figure 1 for Characteristics of FIR Filter
0 kHz–90.625 kHz
±0.005
dB max
96.92 kHz
–3
dB min
104.6875 kHz to 12.395 MHz
90
dB typ
CLOCK
MCLK Duty Ratio
45 to 55
% max
For Specified Operation
VMCLKH, MCLK High Voltage
4
V min
MCLK Uses CMOS Logic
VMCLKL, MCLK Low Voltage
0.4
V max