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INA283-Q1: Measure the high voltage 100-200VDC 1mA-2A

Part Number: INA283-Q1
Other Parts Discussed in Thread: INA283, INA285, TINA-TI, TMCS1100, TMCS1101, INA226, INA228, OPA2192

Hello  TI team 

1.There is a project that require measure the current but the common voltage is between 100VDC  to 200VDC bidirectional.

2.I am plan use the INA283 by division the voltage so it can work well ?

3.Can you give some other solutions ?

4. There is a similar thread https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/988075/ina283-q1-extend-common-mode-voltage-range?tisearch=e2e-sitesearch&keymatch=ina283#

require.pdf

  • Hello valued engineer,

    I am looking this over and will respond shortly.

    Sincerely,

    Peter

  • Hello again,

    So overall using the resistor divider approach to bring down the input VCM for INA283 (or any other CSA) is not a recommended solution. It does bring down the VCM, but it reduces the overall circuit gain and introduces large error that would have to be calibrated out. If this approach is chosen, then there needs to be thorough error analysis that considers variation in bus voltage, 499k resistors, the differential input resistance (Rdiff) of INA283, the variation in INA283 input bias currents (IB), and how all of these could vary over temperature. Ideally, you could calibrate every circuit on every power up at least for offset and then make sure calibrated error is less than what your system allows. You can reduce the effect of the input resistor error by reducing the 499kΩ’s, but this will come at the expense of power losses from resistors. I recommend experimenting in simulation (TINA-TI or PSPICE for TI) to see if there is a feasible solution with tolerable error. You can also choose a higher gain device such as INA285 (1000 V/V) so the input resistors bring the total gain to something still usable (~15 to 20V/V).

    ina283e2e.TSC

    Note in the simulation schematic I added a large input capacitor at INA283 input because device will need this in real world to help maintain a stable input voltage. For more information I recommend the following video:

    https://training.ti.com/ti-precision-labs-current-sense-amplifiers-input-filter-error

     

    The other options to extending VCM range are:

    1. Use isolated solution
      1. TMCS1100/TMCS1101 or TMS1107
      2. Isolated amplifiers such as AMC130x
        1. https://www.ti.com/isolation/isolated-amplifiers/overview.html
      3. Isolated ADCs
        1. https://www.ti.com/isolation/isolated-adcs/overview.html 

     

    1. Float and power a CSA (configured as current-output) with a Zener diode and level-shift the output using a FET/BJT
      1. This document shows how to do it for a unidirectional current
        1. https://www.ti.com/lit/ug/tidu833/tidu833.pdf
      2. This Figure 17 of following document shows how to measure bi-directional current of current-output modified CSA.
        1. https://www.ti.com/lit/an/slya047/slya047.pdf
      3. These documents show how to convert any voltage-output CSA into a current-output
        1. https://www.ti.com/lit/an/sboa358/sboa358.pdf
        2. https://www.ti.com/lit/an/sboa513/sboa513.pdf

     

    1. Float a digital power monitor (e.g., INA226 or INA228) and isolate the digital bus line with a digital isolator
      1. This document shows how to do it: 
        1. https://www.ti.com/lit/ug/tidu361a/tidu361a.pdf
      2. Here is where to find a digital isolator:
        1. https://www.ti.com/isolation/digital-isolators/overview.html 

    You can also use two CSAs one to measure positive and the other to measure negative current , but this will require either two ADC inputs (one for positive and the other for negative) or one ADC input for the current and another ADC/GPIO input to know which way the current is flowing.

    Hope this helps.

    Best,

    Peter

     

  • Hello peter

    Thank you for your much imformation

    1. I think it will take some days to study.If I have some update I will let you know the progress。

    Best

    Thomas

  • Hello Peter

    1. I choose the option 1 to measure the high voltage current, Can you help to check the schematic.

    2. Can it the current accuracy achieve ±2mA?

    04_HVCurrentMeasure.pdf

    Best

    Thomas

  • Hey Thomas,

    I am looking into this and will respond later today.

    Best,

    Peter

  • Hi Peter 

    1. I am update circuit some details so that you can analyze more careful。

    04_HVCurrentMeasure2.pdf

  • Hey Thomas,

    So there are a few things to note here. Firstly I am a little confused why you have the 0.1Ω resistor connecting the input pins of TMCS1100. Remember that the TMCS1100 is a hall-effect current sensor and it measures the current that flows into IN+ and out of IN-. You may want to remove R37 unless I am missing something because it is taking current away from TMCS1100 and this increase error because TMCS1100 is not sensing the largest possible current.

    The TMCS1100 is more optimized to measure larger currents up to 30A RMS and as such it has an input offsets up to ±40mA and gain errors up to 0.7%. Thus, achieving +/-2mA error is just about impossible for measuring 200mA where max possible Vout is 8mV+ 2.5V.

    You may need to find a higher gain, lower offset option to achieve your accuracy at ± 200mA.

    As for the RMS-DC IC, it seems this device has a rather large output impedance ~85kΩ, thus I do not think it is a good idea to place a resistor divider off its output. Why not just buffer the output directly into the OPA2192 IN+ (non-inverting) pin?

    Sincerely,

    Peter

  • Hello Peter 

    Thank you very much, your suggest is very good, I will modify the circuit again

    Best Wish

    Thomas