XR620A Datasheet, PDF (12/15 Pages) Exar Corporation – Instrumentation Amplifier

XR620A
+ Input
+V _S
+
_
100
-
R_G
XR620A
100
-
+
-V _S
+
REF
- Input
-V _S
Figure 3: Differential Shield Driver
Output
Pressure Measurement Applications
The XR620A is especially suitable for higher resistance
pressure sensors powered at lower voltages where small
size and low power become more significant.
Figure 3 shows a 3kΩ pressure transducer bridge powered
from 5V. In such a circuit, the bridge consumes only 1.7mA.
Adding the XR620A and a buffered voltage divider allows
the signal to be conditioned for only 3.8mA of total supply
current.
Small size and low cost make the XR620A especially
attractive for voltage output pressure transducers. Since it
delivers low noise and drift, it will also serve applications such
as diagnostic noninvasive blood pressure measurement.
Medical ECG
The XR620A is perfect for ECG monitors because of its low
current noise. A typical application is shown in Figure 4. The
XR620A’s low power, low supply voltage requirements, and
space-saving 8-lead SOIC package offerings make it an
excellent choice for battery-powered data recorders.
Furthermore, the low bias currents and low current noise,
coupled with the low voltage noise of the XR620A, improve
the dynamic range for better performance.
The value of capacitor C1 is chosen to maintain stability
of the right leg drive loop. Proper safeguards, such as
isolation, must be added to this circuit to protect the patient
from possible harm.
5V
5V
3k
3k
3k
3k
1.7mA
5V
20k
+
G = 100
XR620A
499
_
REF
10k
0.1mA
20k
1.3mA
5V
+
CLCxxx
_
Ref
IN
AGND
Digital
Data
Output
Figure 4: Pressure Monitoring Circuits Operating on a Single 5V Supply
Patient/Circuit
Protection/Isolation
R1
C1 10kΩ
R4
1MΩ
CLC1003
+3V
R3
24.9kΩ
R2
24.9kΩ
3
8
RG
8.25kΩ
1
2
7
XR620A
G=7
5
4
–3V
0.03Hz
6 High-Pass G = 143
Filter
Output
Amplifier
Output
1V/mV
Figure 5: Typical Circuit for ECG Monitor Applications
© 2013-2015 Exar Corporation
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exar.com/XR620A
Rev 1B