SBOU272 November   2021 INA2126 , INA2128

 

  1.   Trademarks
  2. 1Overview
    1. 1.1 Features
    2. 1.2 INA Pinout
    3. 1.3 Compatible Devices
  3. 2Quick Start
    1. 2.1 Dual-Supply Configuration
    2. 2.2 Single-Supply Configuration
      1. 2.2.1 Direct Reference Connection
      2. 2.2.2 Buffered-Reference Voltage Connection
  4. 3EVM Components
    1. 3.1 Power
    2. 3.2 Inputs
      1. 3.2.1 Input Filtering
    3. 3.3 Output
      1. 3.3.1 Output Filtering
    4. 3.4 Reference
    5. 3.5 Miscellaneous
  5. 4Schematic, PCB Layout, and Bill of Materials
    1. 4.1 Schematic
    2. 4.2 PCB Layout
    3. 4.3 Bill of Materials

2.2.2 Buffered-Reference Voltage Connection

A buffered-reference configuration is useful when the source impedance is high (for example, a voltage divider). Buffering a high-impedance source with an operational amplifier provides a low-impedance source and preserves common-mode rejection. Figure 2-3 shows an example of how to set up the EVM for single-supply operation with a buffered-reference voltage connection. Depending on the application, desirable single-supply buffer operational amplifiers include the OPA2330 and OPA2376. The OPA2202 is a good choice for high-voltage applications.

Figure 2-3 Single-Supply Configuration, Buffered Reference Connection
  1. +VS to test point TP1
  2. GND to test points TP11 AND TP12
  3. OAV+ to test point TP2
  4. Install jumper shunt on positions 2 and 3 on J1 and J2
  5. Remove resistor R5 for REFA
    1. Remove resistor R25 for REFB
  6. Populate R1, R4, R6, and R7 with a 0-Ω resistor for channel A
    1. Populate R18, R24, R26, and R27 with a 0-Ω resistor for channel B
  7. Reference voltage to test point OAVinA+ (TP13)
    1. Reference voltage to test point OAVinB+ (TP19)
  8. Differential input signal connect to test points VinA– (TP14) and VinA+ (TP17) of channel A
    1. Differential input signal connect to test points VinB– (TP20) and VinB+ (TP22) of channel B
  9. Observe output at test point VOA (TP15)
    1. Observe output at test point VOB (TP21)
Note: C15 and C22 are prepopulated with 0.1-µF power-supply decoupling capacitors. C22 is not required to be removed for proper single-supply operation. See the respective device data sheet for additional power-supply decoupling information.