Datasheet

AD7176-2 Data Sheet
Rev. A | Page 16 of 68
GETTING STARTED
The AD7176-2 offers the user a fast settling, high resolution,
multiplexed ADC with high levels of configurability.
• Two fully differential or four single-ended analog inputs.
• Crosspoint multiplexer selects any analog input combina-
tion as the input signals to be converted, routing them to
the modulator positive or negative input.
• Fully differential input, single-ended relative to any analog
input and pseudo differential configuration available.
• Per channel configurability—up to four different setups
can be defined. A separate setup can be mapped to each of
the channels. Each setup allows the user to configure:
• Gain and offset correction
• Filter type
• Output data rate
• Reference source selection (internal/external)
The AD7176-2 includes a precision 2.5 V low drift (2 ppm/°C)
band gap internal reference. This reference can be selected to
be used for the ADC conversions, reducing the external com-
ponent count. Alternatively, the reference can be output to the
REFOUT pin to be used as a low noise biasing voltage for the
external circuitry. An example of this is using the REFOUT
signal to set the input common mode for an external driving
amplifier.
The AD7176-2 includes two separate linear regulator blocks for
both the analog and digital circuitry. The analog LDO regulates
the AVDD2 supply to 2 V supplying the ADC core. The user
can tie the AVDD1 and AVDD2 supplies together for easiest
connection. If there is already a clean analog supply rail in the
system in the range of 2 V to 5 V, the user can also choose to
connect this to the AVDD2 input, allowing for lower power
dissipation.
Figure 24. Typical Connection Diagram
DGND
AIN4
AD7176-2
IOVDD
CS
SYNC/ERROR SYNC/ERROR
REGCAPD
REFOUT
AVSS
0.1µF
REGCAPA
AVDD2
AVDD1
XTAL1
GPIO 1
4
2
3
1
24
23
22
21
19
20
9
10
11
12
13
14
15
16
17
18
7
8
5
6
6
85
31
4
7
2
REF–
REF+
2.5V REFERENCE
OUTPUT
4.7µF0.1µF
0.1µF
VOUTGND
NCV
IN
0.1µF
4.7µF
VIN
0.1µF
ADR445BRZ
IOVDD
AVDD2
0.1µF
AVDD1
0.1µF
CX1
16MHz
CX2
0.1µF
1µF
0.1µF 1µF
GENERAL PURPOSE IO
0 AND 1
OUTPUT HIGH = AVDD
OUTPUT LOW = AVSS
FOR SINGLE SUPPLY
CASE OUTPUT HIGH = 5V
OUTPUT LOW = GND
OPTIONAL EXTERNAL
CRYSTAL CIRCUITRY
CAPACITORS
GPIO 0
CLKIN
OPTIONAL
EXTERNAL
CLOCK
INPUT
AIN0
AIN1
AIN2
AIN3
AIN4
SEE ANALOG INPUT SECTION FOR FURTHER DETAILS
IN0
IN4
IN1
IN2
IN3
GPIO 0
GPIO 1
CLKI0/XTAL2
DOUT/RDY
DIN
SCLK
CS
DOUT/RDY
DIN
SCLK
11037-051