OPA197_16 Datasheet, PDF (27/39 Pages) Texas Instruments – 36-V, Precision, Rail-to-Rail Input/Output, Low Offset Voltage Operational Amplifiers

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8 Application and Implementation
OPA197, OPA2197, OPA4197
SBOS737A – JANUARY 2016 – REVISED JULY 2016
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
The OPAx197 family offers outstanding dc precision and ac performance. These devices operate up to 36-V
supply rails and offer true rail-to-rail input/output, ultralow offset voltage and offset voltage drift, as well as
10-MHz bandwidth and high capacitive load drive. These features make the OPAx197 a robust, high-
performance operational amplifier for high-voltage industrial applications.
8.2 Typical Applications
8.2.1 16-Bit Precision Multiplexed Data-Acquisition System
Figure 53 shows a 16-bit, differential, 4-channel, multiplexed data-acquisition system. This example is typical in
industrial applications that require low distortion and a high-voltage differential input. The circuit uses the
ADS8864, a 16-bit, 400-kSPS successive-approximation-resistor (SAR) analog-to-digital converter (ADC), along
with a precision, high-voltage, signal-conditioning front end, and a 4-channel differential multiplexer (mux). This
application example explains the process for optimizing the precision, high-voltage, front-end drive circuit using
the OPA197 and OPA140 to achieve excellent dynamic performance and linearity with the ADS8864.
1
Very Low Output Impedance
Input-Filter Bandwidth
2
High-Impedance Inputs
No Differential Input Clamps
Fast Settling-Time Requirements
3
Attenuate High-Voltage Input Signal
Fast-Settling Time Requirements
Stability of the Input Driver
4
Attenuate ADC Kickback Noise
VREF Output: Value and Accuracy
Low Temp and Long-Term Drift
±20-V,
10-kHz
Sine Wave
±20-V,
10-kHz
Sine Wave
+
OPA197
+
OPA197
CH0+
CH0-
4:2
Mux
+
OPA197
+
OPA197
CH3+
CH3-
n
High-Voltage Multiplexed Input
OPA197
+
+
OPA197
Gain
Network
Gain
Network
Gain
Network
OPA140
+
High-Voltage Level Translation
REF3240
Voltage
Divider
VCM
OPA350
VCM Generation Circuit
5
Fast logic transition
Voltage
Reference
RC Filter Buffer
Reference Driver
RC Filter
Antialiasing
Filter
VINP
REFP
SAR
ADC
VINM
CONV
16 Bits
400 kSPS
Counter
n
Shmidtt
Trigger
Delay
Digital Counter For Multiplexer
Figure 53. OPA197 in 16-Bit, 400-kSPS, 4-Channel, Multiplexed Data Acquisition System for High-Voltage
Inputs With Lowest Distortion
Copyright © 2016, Texas Instruments Incorporated
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Product Folder Links: OPA197 OPA2197 OPA4197