• State Resolved
  • Locked Locked
  • Replies 5 replies
  • Subscribers 47 subscribers
  • Views 475 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

INA236: Clarification on INA236 Connection for Sensing Variable DC-DC Output

Sebastian Cardona Ramirez
Prodigy 120 points

Part Number: INA236
Other Parts Discussed in Thread: INA326

Hello,

I’m currently working with the INA236, and I have a few doubts regarding its correct configuration and usage, since I find some aspects a bit confusing.

I want to measure the output voltage and current of a variable DC-DC converter using the INA236 together with an INA326, as shown in Figure 1 of my setup.
My goal is to correctly sense the output voltage, but to achieve the required measurement range, I need to configure the INA236 in common-mode operation.
image.png

Figure 1.

According to the datasheet, the shunt resistors must be selected based on the desired voltage and current ranges. However, I would like to understand what happens if I use shunt resistor values designed for higher voltage ranges than those actually present at my output.

Additionally, I’d like to confirm whether my connection setup is correct, since in Figure 2 from the evaluation board documentation, the wiring appears to be different, and I’m not sure why.

image.png

Figure 2.

I also have a conceptual question:
Could you please explain the difference between a shunt resistor and a regular resistor, and why a specific “shunt” type is required for this application? I’d like to understand how its characteristics (such as tolerance, temperature coefficient, and power rating) affect the current-sensing accuracy. 

Could you please help me understand:

  1. The correct location and conection where I should place my load (which will be powered by the buck-boost converter).

  2. How to properly configure the circuit so that I can accurately sense both voltage and current at the DC-DC output.

Thank you very much for your help and any clarification you can provide.

Best regards,
Sebastián Cardona Ramírez

  • +1
    TI__Mastermind 36820 points

    Hi Sebastián,

    We have a library of videos that go into different topics related to current sensing. I believe your questions are well answered there. For example you can find a video dedicated to shunt resistors.   

    To measure both current and voltage, INA236 needs to be in a high-side configuration. In your diagram, if INA236 input is connected across the Rshunt that sits in between the DCDC and LOAD, then it is in high-side configuration.

    Regards

    Guang

  • 0 in reply to Guang Zhou
    Prodigy 120 points

    Hello Guang,

    I would like to request official confirmation regarding the INA236 operation, particularly how it performs current and bus-voltage measurements, how the ADC sequencing works in each mode, and how data is handled through the I²C interface.

    Based on the datasheet, here is my current understanding — please confirm if the following is correct:

    1. Measurement sequencing

    From section 7.4.1 – Continuous Versus Triggered Operation, the INA236 “continuously converts a shunt voltage reading followed by a bus voltage reading” when MODE = 111b.

    Please confirm that:

    • The INA236 does not measure shunt (current) and bus voltage simultaneously, but rather performs these conversions sequentially using its internal ADC multiplexer.

    • In continuous mode, the device repeatedly performs the cycle:
      Shunt measurement → Bus measurement → Shunt measurement → Bus measurement, indefinitely.

    • In triggered (single-shot) mode, one write command triggers a single pair of conversions (one shunt and one bus voltage measurement).

    2. Data update and I²C transmission behavior

    From section 7.5.2 – Writing to and Reading Through the I²C Serial Interface and 7.4.1 – Continuous Versus Triggered Operation:

    Please confirm that:

    • The INA236 does not automatically send data over the I²C bus — the master must always request a read.

    • The internal result registers are overwritten after each new conversion cycle (the previous data is replaced).

    • The last measured values remain available to the I²C master until the next conversion is completed.

    • The CVRF bit indicates when new data is available after averaging and power calculations are done.

    • There is no cyclic data broadcast or background data transmission — all data movement happens only when the I²C master initiates communication.

    3. Confirmation of datasheet consistency

    Please confirm that the behavior described in sections 7.3.1, 7.3.2, and 7.4.1 correctly reflects the internal conversion sequence and data update mechanism for the INA236.

  • +1 in reply to Sebastian Cardona Ramirez
    TI__Mastermind 36820 points

    Hi Sebastián,

    Your understanding is spot on. The datasheet descriptions of the conversion sequence, data transmission and I2C interface are accurate. There are no inconsistencies that we’re aware of.

    Regards

    Guang

  • 0 in reply to Guang Zhou
    Prodigy 120 points

    Hi Guang,

    Thank you very much for confirming that my understanding of the conversion sequence and I²C data handling is correct. That really helps to validate my design.

    I just have one more question to make sure I implement the hardware connection properly:
    Could you please confirm or illustrate the correct way to connect the INA236 with the load in order to sense both current and voltage simultaneously?This clarification will help me finalize my PCB design and ensure accurate current and voltage sensing in continuous mode (MODE = 111b).

    Thank you again for your time and support!

    Best regards,
    Sebastián Cardona Ramírez

  • +1 in reply to Sebastian Cardona Ramirez
    TI__Mastermind 36820 points

    Hi Sebastián,

    To measure both current and volage (also power which is a math in the background), INA236 needs to be connected in a high-side configuration, like figure 8.1. Inside the device, the ADC is muxed between current and voltage in a ping-pong style and is measured sequentially.

    Regards

    Guang