ADA4941-1YRZ-RL Analog Devices Inc, ADA4941-1YRZ-RL Datasheet - Page 22

• Manufacturer Part Number: ADA4941-1YRZ-RL
• Description: Amplifier, Other
• Manufacturer: Analog Devices Inc
• Type: ADC Driverr

Specifications of ADA4941-1YRZ-RL

• Design Resources: Converting a Single-Ended Signal with AD7982 Differential PulSAR ADC (CN0032) Converting a Single-Ended Signal with AD7984 Differential PulSAR ADC (CN0033)
• Applications: Data Acquisition
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ADA4941-1
DRIVING THE AD7687 ADC
The ADA4941-1 is an excellent driver for high resolution
ADCs, such as the AD7687, as shown in Figure 56. The Sallen-
Key, low-pass filter shown in Figure 54 is included in this
example but is not required. The circuit shown in Figure 56
accepts single-ended input signals that swing between 0 V and 3 V.
The
buffered by one of the
AD7687
of 6 V. The reference voltage is also divided by two and buffered
to supply the midsupply REF level of 1.5 V for the ADA4941-1.
ADR443
REF input, providing a differential input full-scale level
+5V
10µF
provides a stable, low noise, 3 V reference that is
0.1µF
AD8032
VIN
0V TO 3V
2
562Ω
V
IN
amplifiers and applied to the
ADR443
GND
4
3.9nF
562Ω
V
OUT
10nF
6
562Ω
VIN
1kΩ
R
G
0.1µF
1.69kΩ
Figure 56. ADA4941-1 Driving the AD7687 ADC
500Ω
560pF
3
2
1
8
Figure 57. Gain of −2 Configuration
1
8
8
4
FB
IN
FB
IN
AD8032
+5V
6
–5V
1kΩ
6
–5V
1/2
R
Rev. B | Page 22 of 24
0.1µF
F
3
A1
3
A1
1
V
V
V
V
+5V
+5V
S+
S–
S+
S–
2
2
ADA4941-1
REF
REF
10µF
500Ω
1kΩ
500Ω
10µF
1kΩ
GAIN OF −2 CONFIGURATION
The ADA4941-1 can be operated in a configuration referred
to as gain of −2. Clearly, a gain of −2 can be achieved by
simply swapping the outputs of a gain of +2 circuit, but the
configuration described here is different. The configuration is
referred to as having negative gain to emphasize that the input
amplifier, A1, is operated as an inverting amplifier instead of in
its usual noninverting mode. As implied in its name, the voltage
gain from VIN to V
of −2 configuration on ±5 V supplies.
The gain of −2 configuration is most useful in applications that
have wide input swings because the input common-mode
voltages are held at constant levels. The signal size is therefore
constrained by the output swing limits. The gain of −2 has a low
input resistance that is equal to R
1kΩ
1kΩ
1kΩ
A2
1kΩ
A2
0.1µF
0.1µF
5
6
OUT+
OUT–
V
AD8032
O, dm
OUT+
OUT–
+
–
1/2
4
5
O
7
, dm is −2 V/V. See Figure 57 for the gain
4
5
33Ω
33Ω
2.7nF
2.7nF
G
.
3
4
0.1µF
IN+
IN–
AD7687
VDD
GND
5
2
REF
1