AD7193 Datasheet, PDF (28/56 Pages) Analog Devices – 4-Channel, 4.8 kHz, Ultralow Noise, 24-Bit Sigma-Delta ADC with PGA

AD7193
ADC CIRCUIT INFORMATION
5V
IN+
OUT–
OUT+
IN–
REFIN1(+) ^{AGND AV}DD
AIN1
AIN2
AIN3
AIN4
AIN5
AIN6
MUX
AIN7
AIN8
AINCOM
AV_DD
AGND
REFIN1(–)
PGA
TEMP
SENSOR
DV_DD DGND
MODULATOR
AND FILTER
Σ-Δ ADC
CALIBRATION
BPDSW
AGND
AD7193
CLOCK
CIRCUITRY
REFERENCE
DETECT
SERIAL
INTERFACE
AND
CONTROL
LOGIC
DOUT/RDY
DIN
SCLK
CS
SYNC
P3
P2
MCLK1 MCLK2 P0/REFIN2(–) P1/REFIN2(+)
Figure 21. Basic Connection Diagram
OVERVIEW
Sigma-Delta (ΣΔ) ADC and Filter
The AD7193 is an ultralow noise ADC that incorporates a Σ-Δ
modulator, a buffer, PGA, and on-chip digital filtering intended
for the measurement of wide dynamic range signals such as
those in pressure transducers, weigh scales, and strain gage
applications. Figure 21 shows the basic connections required
to operate the part.
Analog Inputs
The device can be configured to have four differential or eight
pseudo differential analog inputs. The analog inputs can be
buffered or unbuffered.
Multiplexer
The on-chip multiplexer increases the channel count of the
device. Because the multiplexer is included on chip, any channel
changes are synchronized with the conversion process.
PGA
The analog input signal can be amplified using the PGA. The
PGA allows gains of 1, 8, 16, 32, 64, and 128.
Reference Detect
The AD7193 is capable of monitoring the external reference. If
the reference is not present, a flag is set in the status register of
the device.
Burnout Currents
Two 500 nA burnout currents are included on-chip to detect
the presence of the external sensor.
The AD7193 contains a fourth-order Σ-Δ modulator followed
by a digital filter. The device has several filter options
• Sinc⁴
• Sinc³
• Chop enabled/disabled
• Fast settling
• Zero latency
Serial Interface
The AD7193 has a 4-wire SPI interface. The on-chip registers
are accessed via the serial interface.
Clock
The AD7193 has an internal 4.92 MHz clock. Either this clock
or an external clock can be used as the clock source to the AD7193.
The internal clock can also be made available on a pin if a clock
source is required for external circuitry.
Bridge Power-Down Switch
External circuitry such as strain gages or bridges can be
powered up/down using the bridge power-down switch.
Temperature Sensor
The on-chip temperature sensor monitors the die temperature.
Digital Outputs
The AD7193 has four general-purpose digital outputs. These
can be used for driving external circuitry. For example, an
external multiplexer can be controlled by these outputs.
Calibration
Both internal and system calibration are included on chip;
therefore, the user has the option of removing offset/gain errors
internal to the AD7193 only, or removing the offset/gain errors
of the complete end system.
Rev. A | Page 28 of 56