Low Power, 24-Bit, 31.25 kSPS, Sigma-Delta
ADC with True Rail-to-Rail Buffers
Data Sheet
AD7172-4
Rev. 0 Document Feedback
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 ©2015 Analog Devices, Inc. All rights reserved.
Technical Support www.analog.com
FEATURES
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
GENERAL DESCRIPTION
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
AVDD
AVSS
AVSS
PDSW GPIO0 GPIO1 GPO2 GPO3 XTAL1 XTAL2/CLKIO DGND
REF– REF+AVDD2 REGCAP
A
AIN0/REF2–
A
IN1/REF2+
AIN7
AIN8
Σ-∆ ADC
1.8V
LDO
1.8V
LDO
IOVDD REGCAPD
SERIAL
INTERFACE
AND CONTROL
DIGITAL
FILTER
AD7172-4
XTAL AND INTERNAL
CLOCK OSCILLATOR
CIRCUITRY
CS
SCLK
DIN
DOUT/RDY
SYNC
ERROR
I/O AND EXTERNAL
MUX CONTROL
12676-001
RAIL-TO-RAIL
REFERENCE
INPUT
BUFFERS
RAIL-TO-RAIL
ANALOG
INPUT
BUFFERS
CROSSPOINT
MULTIPLEXER
Figure 1.
评论1