AD7172-4 Datasheet, PDF (1/61 Pages) Analog Devices – Low Power, 24-Bit, 31.25 kSPS, Sigma-Delta ADC with True Rail-to-Rail Buffers

Data Sheet
Low Power, 24-Bit, 31.25 kSPS, Sigma-Delta
ADC with True Rail-to-Rail Buffers
AD7172-4
FEATURES
GENERAL DESCRIPTION
Fast and flexible output rate: 1.25 SPS to 31.25 kSPS
Channel scan data rate of 6.21 kSPS/channel (161 μs settling)
Performance specifications
17.2 noise free bits at 31.25 kSPS
24 noise free bits at 5 SPS
INL: ±2 ppm of FSR
85 dB rejection of 50 Hz and 60 Hz with 50 ms settling
User configurable input channels
4 fully differential channels or 8 single-ended channels
Crosspoint multiplexer
True rail-to-rail analog and reference input buffers
Internal or external clock
Power supply
AVDD1 = 3.0 V to 5.5 V, AVDD2 = IOVDD = 2 V to 5.5 V
Split supply with AVDD1 and AVSS at ±2.5 V or ±1.65 V
ADC current: 1.5 mA
Temperature range: −40°C to +105°C
3- or 4-wire serial digital interface (Schmitt trigger on SCLK)
Serial port interface (SPI), QSPI-, MICROWIRE-, and DSP-
compatible
APPLICATIONS
Process control: PLC/DCS modules
Temperature and pressure measurement
Medical and scientific multichannel instrumentation
Chromatography
The AD7172-4 is a low noise, low power, multiplexed, Σ-Δ analog-
to-digital converter (ADC) with 4- or 8-channel (fully differential/
single-ended) inputs for low bandwidth signals. The AD7172-4
has a maximum channel scan rate of 6.21 kSPS (161 μs) for fully
settled data. The output data rates range from 1.25 SPS to 31.25 kSPS.
The AD7172-4 integrates key analog and digital signal condition-
ing blocks to allow users to configure an individual setup for
each analog input channel in use via the SPI. Integrated true rail-to-
rail buffers on the analog inputs and reference inputs provide easy
to drive high impedance inputs.
The digital filter allows simultaneous 50 Hz and 60 Hz rejection
at a 27.27 SPS output data rate. The user can switch between
different filter options according to the demands of each channel
in the application, with further digital processing functions such
as offset and gain calibration registers, which are configurable
on a per channel basis. General-purpose input/outputs (GPIOs)
control external multiplexers synchronous to the ADC conversion
timing. The specified temperature range is −40°C to +105°C.
The AD7172-4 is in a 5 mm × 5 mm, 32-lead LFCSP.
Note that, throughout this data sheet, the dual function pin
names are referenced by the relevant function only.
FUNCTIONAL BLOCK DIAGRAM
AVDD1 AVDD2 REGCAPA REF– REF+
IOVDD REGCAPD
AIN0/REF2–
AIN1/REF2+
CROSSPOINT
MULTIPLEXER
1.8V
LDO
RAIL-TO-RAIL
AVDD
ANALOG
INPUT
BUFFERS
RAIL-TO-RAIL
REFERENCE
INPUT
BUFFERS
Σ-∆ ADC
DIGITAL
FILTER
1.8V
LDO
SERIAL
INTERFACE
AND CONTROL
AIN7
AIN8
AVSS
I/O AND EXTERNAL
MUX CONTROL
XTAL AND INTERNAL
CLOCK OSCILLATOR
CIRCUITRY
AD7172-4
CS
SCLK
DIN
DOUT/RDY
SYNC
ERROR
AVSS
PDSW
GPIO0 GPIO1 GPO2 GPO3
XTAL1 XTAL2/CLKIO
Figure 1.
DGND
Rev. A
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