EVAL-AD7694CBZ Analog Devices Inc, EVAL-AD7694CBZ Datasheet - Page 14

• Manufacturer Part Number: EVAL-AD7694CBZ
• Description: BOARD EVALUATION FOR AD7694
• Manufacturer: Analog Devices Inc
• Series: PulSAR®r

Specifications of EVAL-AD7694CBZ

• Number Of Adc's: 1
• Number Of Bits: 16
• Sampling Rate (per Second): 250k
• Data Interface: Serial
• Inputs Per Adc: 1 Differential
• Input Range: ±VREF
• Power (typ) @ Conditions: 6.3mW @ 250kSPS
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Utilized Ic / Part: AD7694
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AD7694
Table 9. Recommended Driver Amplifiers
Amplifier
AD8021
AD8022
OP184
AD8605, AD8615
AD8519
AD8031
VOLTAGE REFERENCE INPUT
The AD7694 voltage reference input, REF, has a dynamic input
impedance and should therefore be driven by a low impedance
source with efficient decoupling between the REF and GND
pins, as explained in the Layout section.
When REF is driven by a very low impedance source (for
example, an unbuffered reference voltage like the low
temperature drift
the
chip capacitor is appropriate for optimum performance.
If desired, smaller reference decoupling capacitor values down
to 2.2 μF can be used with a minimal impact on performance,
especially DNL.
POWER SUPPLY
The AD7694 powers down automatically at the end of each
conversion phase and, therefore, the power scales linearly with
the sampling rate, as shown in Figure 22. This makes the part
ideal for a low sampling rate (even a few Hz) and low battery-
powered applications.
AD8031
10,000
1,000
0.01
100
0.1
10
1
10
Figure 22. Operating Current vs. Sampling Rate
or the AD8605), a 10 μF (X5R, 0805 size) ceramic
ADR43x
100
Typical Application
Very low noise and high frequency
Low noise and high frequency
Low power, low noise, and low frequency
5 V single-supply and low power
Small, low power, and low frequency
High frequency and low power
SAMPLING RATE (SPS)
reference or a reference buffer using
1k
VDD = 5V
10k
VDD = 2.7V
100k
1M
Rev. A | Page 14 of 16
SUPPLYING THE ADC FROM THE REFERENCE
For simplified applications, the AD7694, with its low operating
current, can be supplied directly using the reference circuit, as
shown in Figure 23. The reference line can be driven by either
•
•
•
OR
5V
3V
NOTES
1. OPTIONAL REFERENCE BUFFER AND FILTER.
The system power supply directly
A reference voltage with enough current output capability,
such as the
A reference buffer, such as the AD8031, that can also filter
the system power supply, as shown in Figure 23
10kΩ
1μF
Figure 23. Example of an Application Circuit
ADR43x
5V OR 3V
(NOTE 1)
AD8031
10μF
2.2
TO
5V OR 3V
REF
AD7694
10Ω
VDD
1μF