18-Bit, 250 kSPS, Differential
Programmable Input PulSAR® ADC
AD7631
FEATURES
FUNCTIONAL BLOCK DIAGRAM
TEMP REFBUFIN REF REFGND VCC VEE DVDD DGND
Multiple pins/software-programmable input ranges
+5 V (10 V p-p), +10 V (20 V p-p), 5 V (20 V p-p),
10 V (40 V p-p)
Pins or serial SPI-compatible input ranges/mode selection
Throughput: 250 kSPS
INL: 1.5 LSB typical, 2.5 LSB maximum ( 9.5 ppm of FSR)
18-bit resolution with no missing codes
Dynamic range: 102.5 dB
OVDD
AGND
AD7631
REF
OGND
AVDD
PDREF
PDBUF
IN+
AMP
SERIAL DATA
PORT
REF
SERIAL
CONFIGURATION
PORT
18
SWITCHED
CAP DAC
D[17:0]
BUSY
RD
IN–
PARALLEL
INTERFACE
SNR: 101 dB @ 2 kHz
THD: −112 dB @ 2 kHz
iCMOS® process technology
5 V internal reference: typical drift 3 ppm/°C; TEMP output
No pipeline delay (SAR architecture)
Parallel (18-/16-/8-bit bus) and serial 5 V/3.3 V interface
SPI-/QSPI™-/MICROWIRE™-/DSP-compatible
Power dissipation
CS
CLOCK
CNVST
PD
D0/OB/2C
D1/A0
CONTROL LOGIC AND
CALIBRATION CIRCUITRY
RESET
D2/A1
BIPOLAR TEN
MODE0
MODE1
Figure 1.
Table 1. 48-Lead PulSAR Selection
73 mW @ 250 kSPS
10 mW @ 1 kSPS
Pb-free, 48-lead LQFP and 48-lead LFCSP (7 mm × 7 mm)
100 to
250
(kSPS)
500 to
570
570 to
1000
Res
(Bits)
>1000
(kSPS)
Input Type
(kSPS)
(kSPS)
Bipolar
14
14
AD7951
AD7952
APPLICATIONS
Process controls
High speed data acquisition
Digital signal processing
Spectrum analysis
ATE
Differential
Bipolar
Unipolar
16
AD7651
AD7660
AD7661
AD7650
AD7652
AD7664
AD7666
AD7653
AD7667
GENERAL DESCRIPTION
Bipolar
16
16
AD7610
AD7663
AD7665
AD7612
AD7671
The AD7631 is an 18-bit, charge redistribution, successive
approximation register (SAR), architecture analog-to-digital
converter (ADC) fabricated on Analog Devices, Inc.’s iCMOS
high voltage process. The device is configured through hardware
or via a dedicated write-only serial configuration port for input
range and operating mode. The AD7631 contains a high speed
18-bit sampling ADC, an internal conversion clock, an internal
reference (and buffer), error correction circuits, and both serial
Differential
Unipolar
AD7675
AD7676
AD7677
AD7621
AD7622
AD7623
Simultaneous/
16
AD7654
AD7655
Multichannel
Unipolar
Differential
Unipolar
18
18
AD7678
AD7631
AD7679
AD7674
AD7634
AD7641
AD7643
CNVST
and parallel system interface ports. A falling edge on
Differential
Bipolar
samples the fully differential analog inputs on IN+ and IN−.
The AD7631 features four different analog input ranges. Power is
scaled linearly with throughput. Operation is specified from
−40°C to +85°C.
Rev. A
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