SBOS620E December   2013  – November 2015 OPA192 , OPA2192 , OPA4192

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1  Absolute Maximum Ratings
    2. 6.2  ESD Ratings
    3. 6.3  Recommended Operating Conditions
    4. 6.4  Thermal Information: OPA192
    5. 6.5  Thermal Information: OPA2192
    6. 6.6  Thermal Information: OPA4192
    7. 6.7  Electrical Characteristics: VS = ±4 V to ±18 V (VS = +8 V to +36 V)
    8. 6.8  Electrical Characteristics: VS = ±2.25 V to ±4 V (VS = +4.5 V to +8 V)
    9. 6.9  Typical Characteristics
    10. 6.10 Typical Characteristics
  7. 7 Parameter Measurement Information
    1. 7.1 Input Offset Voltage Drift
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Input Protection Circuitry
      2. 8.3.2 EMI Rejection
      3. 8.3.3 Phase Reversal Protection
      4. 8.3.4 Thermal Protection
      5. 8.3.5 Capacitive Load and Stability
      6. 8.3.6 Common-Mode Voltage Range
      7. 8.3.7 Electrical Overstress
      8. 8.3.8 Overload Recovery
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 16-Bit Precision Multiplexed Data-Acquisition System
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Application Curve
      2. 9.2.2 Slew Rate Limit for Input Protection
      3. 9.2.3 Precision Reference Buffer
  10. 10Power-Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Development Support
        1. 12.1.1.1 TINA-TI (Free Software Download)
        2. 12.1.1.2 TI Precision Designs
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Related Links
    4. 12.4 Community Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

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9 Application and Implementation

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.

9.1 Application Information

The OPAx192 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 OPAx192 a robust, high-performance operational amplifier for high-voltage industrial applications.

9.2 Typical Applications

9.2.1 16-Bit Precision Multiplexed Data-Acquisition System

Figure 66 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 TI Precision Design details the process for optimizing the precision, high-voltage, front-end drive circuit using the OPA192 and OPA140 to achieve excellent dynamic performance and linearity with the ADS8864.

OPA192 OPA2192 OPA4192 ai_tipd151_bos620.gif Figure 66. OPA192 in 16-Bit, 400-kSPS, 4-Channel, Multiplexed Data Acquisition System for High-Voltage Inputs with Lowest Distortion

9.2.1.1 Design Requirements

The primary objective is to design a ±20 V, differential 4-channel multiplexed data acquisition system with lowest distortion using the 16-bit ADS8864 at a throughput of 400 kSPS for a 10 kHz full-scale pure sine-wave input. The design requirements for this block design are:

  • System Supply Voltage: ±15 V
  • ADC Supply Voltage: 3.3 V
  • ADC Sampling Rate: 400 kSPS
  • ADC Reference Voltage (REFP): 4.096 V
  • System Input Signal: A high-voltage differential input signal with a peak amplitude of 10 V and frequency (fIN) of 10 kHz are applied to each differential input of the mux.

9.2.1.2 Detailed Design Procedure

The purpose of this precision design is to design an optimal high voltage multiplexed data acquisition system for highest system linearity and fast settling. The overall system block diagram is illustrated in Figure 66. The circuit is a multichannel data acquisition signal chain consisting of an input low-pass filter, multiplexer (mux), mux output buffer, attenuating SAR ADC driver, digital counter for mux and the reference driver. The architecture allows fast sampling of multiple channels using a single ADC, providing a low-cost solution. The two primary design considerations to maximize the performance of a precision multiplexed data acquisition system are the mux input analog front-end and the high-voltage level translation SAR ADC driver design. However, carefully design each analog circuit block based on the ADC performance specifications in order to achieve the fastest settling at 16-bit resolution and lowest distortion system. The diagram includes the most important specifications for each individual analog block.

This design systematically approaches each analog circuit block to achieve a 16-bit settling for a full-scale input stage voltage and linearity for a 10-kHz sinusoidal input signal at each input channel. The first step in the design is to understand the requirement for extremely low impedance input-filter design for the mux. This understanding helps in the decision of an appropriate input filter and selection of a mux to meet the system settling requirements. The next important step is the design of the attenuating analog front-end (AFE) used to level translate the high-voltage input signal to a low-voltage ADC input when maintaining amplifier stability. The next step is to design a digital interface to switch the mux input channels with minimum delay. The final design challenge is to design a high-precision, reference-driver circuit that provides the required REFP reference voltage with low offset, drift, and noise contributions.

9.2.1.3 Application Curve

OPA192 OPA2192 OPA4192 ai_linearity_error_bos620.gif Figure 67. ADC 16-Bit Linearity Error for the Multiplexed Data Acquisition Block
OPA192 OPA2192 OPA4192 apps_tipd_logo_bas557.gif
For step-by-step design procedure, circuit schematics, bill of materials, PCB files, simulation results, and test results, refer to TI Precision Design TIDU181, 16-bit, 400-kSPS, 4-Channel, Multiplexed Data Acquisition System for High Voltage Inputs with Lowest Distortion.

9.2.2 Slew Rate Limit for Input Protection

In control systems for valves or motors, abrupt changes in voltages or currents can cause mechanical damages. By controlling the slew rate of the command voltages into the drive circuits, the load voltages ramps up and down at a safe rate. For symmetrical slew-rate applications (positive slew rate equals negative slew rate), one additional op amp provides slew-rate control for a given analog gain stage. The unique input protection and high output current and slew rate of the OPAx192 make the device an optimal amplifier to achieve slew rate control for both dual- and single-supply systems.Figure 68 shows the OPA192 in a slew-rate limit design.

OPA192 OPA2192 OPA4192 ai_slew_rate_limiter_bos620.gif Figure 68. Slew Rate Limiter Uses One Op Amp
OPA192 OPA2192 OPA4192 apps_tipd_logo_bas557.gif
For step-by-step design procedure, circuit schematics, bill of materials, PCB files, simulation results, and test results, refer to TI Precision Design TIDU026, Slew Rate Limiter Uses One Op Amp.

9.2.3 Precision Reference Buffer

The OPAx192 features high output current drive capability and low input offset voltage, making the device an excellent reference buffer to provide an accurate buffered output with ample drive current for transients. For the 10-µF ceramic capacitor shown in Figure 69, RISO, a 37.4-Ω isolation resistor, provides separation of two feedback paths for optimal stability. Feedback path number one is through RF and is directly at the output, VOUT. Feedback path number two is through RFx and CF and is connected at the output of the op amp. The optimized stability components shown for the 10-µF load give a closed-loop signal bandwidth at VOUT of 4 kHz and still provides a loop gain phase margin of 89°. Any other load capacitances require recalculation of the stability components: RF, RFx , CF , and RISO.

OPA192 OPA2192 OPA4192 ai_ref_buffer_bos620.gif Figure 69. Precision Reference Buffer