Datasheet

Data Sheet AD7691
Rev. C | Page 3 of 28
SPECIFICATIONS
VDD = 2.3 V to 5.25 V, VIO = 2.3 V to VDD, V
REF
= VDD, all specifications T
MIN
to T
MAX
, unless otherwise noted.
Table 2.
Parameter Conditions/Comments Min Typ Max Unit
RESOLUTION 18 Bits
ANALOG INPUT
Voltage Range, V
IN
IN+ − (IN−) −V
REF
+V
REF
V
Absolute Input Voltage IN+, IN− −0.1 V
REF
+ 0.1 V
Common-Mode Input Range IN+, IN− V
REF
/2 − 0.1 V
REF
/2 V
REF
/2 + 0.1 V
Analog Input CMRR f
IN
= 250 kHz 65 dB
Leakage Current at 25°C Acquisition phase 1 nA
Input Impedance
1
THROUGHPUT
Conversion Rate VDD = 4.5 V to 5.25 V 0 250 kSPS
VDD = 2.3 V to 4.5 V 0 180 kSPS
Transient Response Full-scale step 1.8 s
ACCURACY
No Missing Codes 18 Bits
Integral Linearity Error −1.5 ±0.75 +1.5 LSB
2
Differential Linearity Error −1 ±0.5 +1.25 LSB
2
Transition Noise REF = VDD = 5 V 0.75 LSB
2
Gain Error
3
VDD = 4.5 V to 5.25 V −40 ±2 +40 LSB
2
VDD = 2.3 V to 4.5 V −80 ±2 +80 LSB
2
Gain Error Temperature Drift ±0.3 ppm/°C
Zero Error
3
VDD = 4.5 V to 5.25 V −0.8 ±0.1 +0.8 mV
VDD = 2.3 V to 4.5 V −3.5 ±0.7 +3.5 mV
Zero Temperature Drift ±0.3 ppm/°C
Power Supply Sensitivity
VDD = 5 V ± 5%
±0.25 LSB
2
AC ACCURACY
4
Dynamic Range V
REF
= 5 V 101 102 dB
Oversampled Dynamic Range
5
f
IN
= 1 kSPS 125 dB
Signal-to-Noise f
IN
= 1 kHz, V
REF
= 5 V 100 101.5 dB
f
IN
= 1 kHz, V
REF
= 2.5 V 95 96.5 dB
Spurious-Free Dynamic Range f
IN
= 1 kHz, V
REF
= 5 V −125 dB
Total Harmonic Distortion f
IN
= 1 kHz, V
REF
= 5 V −118 dB
Signal-to-(Noise + Distortion) f
IN
= 1 kHz, V
REF
= 5 V 100 101.5 dB
f
IN
= 1 kHz, V
REF
= 2.5 V 95 96.5 dB
Intermodulation Distortion
6
115 dB
1
See the Analog Inputs section.
2
LSB means least significant bit. With the ±5 V input range, one LSB is 38.15 µV.
3
See the Terminology section. These specifications include full temperature range variation but not the error contribution from the external reference.
4
All ac accuracy specifications in dB are referred to a full-scale input FSR. Tested with an input signal at 0.5 dB below full scale, unless otherwise specified.
5
Dynamic range obtained by oversampling the ADC running at a throughput f
S
of 250 kSPS, followed by postdigital filtering with an output word rate f
O
.
6
f
IN1
= 21.4 kHz and f
IN2
= 18.9 kHz, with each tone at −7 dB below full scale.