SBOU254A January   2021  – June 2021 INA2191

 

  1.   Trademarks
  2. 1Overview
    1. 1.1 EVM Kit Contents
    2. 1.2 Related Documentation From Texas Instruments
  3. 2Hardware
    1. 2.1 Features
  4. 3Operation
    1. 3.1 Quick Start Setup
    2. 3.2 Measurements
  5. 4EVM Components
    1. 4.1 R1n, R2n, R3n, R4n, R5n, R6n, C1n, C2n, C4n, C5n
      1. 4.1.1 J5n, J6n, JA1n, JA2n
    2. 4.2 C3n
    3. 4.3 Rs1n and Rs2n (Rshunt)
      1. 4.3.1 R7n, R8n
    4. 4.4 U1n (INA2191)
    5. 4.5 S1n, S2n, S3n, S4n, S5n, S6n, S7n, S8n, S9n, SA1n, SA2n, SA3n, SA4n, SA5n, SA6n, SA7n, SA8n, SA9n
  6. 5Schematic, PCB Layout, and Bill of Materials
    1. 5.1 Schematics
    2. 5.2 PCB Layout
    3. 5.3 Bill of Materials
  7. 6Revision History

3.2 Measurements

The user can either emulate the voltage developed across a sense resistor based on a given set of system conditions with the INA2191EVM, or connect the device inputs to an external shunt resistor. The user can also solder a surface-mount technology (SMT) shunt resistor across the Rs+ and Rs– pads, and these inputs can be connected in series with the external system and load.

Note the following where n is gain option 1, 2, 3, 4, or 5.

  • Each device channel has its own pads for an optional shunt resistor

    • Rs1n is shunt resistor for channel 1, while Rs2n is the shunt resistor for channel 2.

    • When running current through Rs1 or Rs2, the user can connect the load and source to the shunt resistor using the quick-connect tabs J1n and J2n for Rs1n or J3n and J4n for Rs2n.

    • All shunt resistors will be referred to as Rshunt.

  • Each device channel has its own input pins with test points

    • IN1+ and IN1– are the silkscreen markings for channel 1 input pins IN+1 and IN–1 respectively.

    • IN2 + and IN2– are the silkscreen markings for channel 2 input pins IN+2 and IN–2 respectively.

    • All input nodes will be referred to as IN+ and IN– or just as input pins.

  • Input pins connect to shunt resistor pads for each channel on each gain variant panel

    • Rs1+ and Rs1– are the same nets as IN1+ and IN1– respectively for channel 1.

    • Rs2+ and Rs2– are the same nets as IN2+ and IN2– respectively for channel 2.

    • The shunt resistor and input pin nodes become different once the input resistors (R3n, R4n, R5n, R6n) are increased to resistance greater than 0 Ω.

To configure a measurement evaluation without a shunt resistor, follow this procedure:

  1. Connect a positive differential voltage across the device channel inputs from IN+ to IN– (or Rs1+ to Rs–) using J1n and J2n tabs for channel 1 and J3n and J4n tabs for channel 2.

    1. For any unused channel, short the inputs and tie these inputs to ground or some other valid common-mode voltage (VCM).

  2. If the differential supply is floating, then connect a –0.1-V to 40-V VCM to the inputs of the device channel. Connect the positive lead of the VCM source to the IN– tab and VCM source ground to a GND test point.
    1. This action effectively raises the absolute common-mode voltage of the input pins, while still retaining a positive input differential signal.
  3. Provide the desired reference voltage to the REF1 node for channel 1 or REF2 node for channel 2.
  4. Measure the output voltage at OUT1/OUT1F for channel or OUT2/OUT2F for channel 2 with respect to ground (GND) or with respect to the channel's reference voltage.

To configure a measurement evaluation with a shunt resistor, follow this procedure:

  1. Solder a 1206 resistor at the Rshunt pads that connects to the IN+ and IN– inputs.
  2. Connect the Rshunt tabs (J1n and J2n for channel 1 or J3n and J4n for channel 2) in series with the load and bus voltage sources while powered off.
    WARNING:

    Make sure that the equipment (shunt resistor, wires, connectors, and so on) can support the amperage and power dissipation first before you measure the current. Also make sure that the current flowing through J1n, J2n, J3n, or J4n does not exceed 5 A. Failure to do so can result in hot surfaces (> 55 °C), damage to the EVM, or personal injury.

  3. Power on the system and measure the output voltage at the OUT/OUTF test points for the correct channel. Output voltage with respect to ground is equal to the gain of the device multiplied by the differential voltage plus the reference voltage, where the differential voltage is the exact voltage from IN+ to IN– input pins.