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TMCS1126: I would like to inquire about the current measurement range(@ 125℃) of TMCS device

Junehee Park
Intellectual 320 points
Part Number: TMCS1126

Tool/software:

Hi~

I am using TMCS1126A7. 

The maximum measured current range is 80A, but at an external temperature of 125℃, it is 44A. 

I would like to measure the range of 0-48A current. 

And because the temperature of the converter board under development can go over 125℃, TMCS1126A7 cannot measure current above 44A (@125℃). 

Q1)The data sheet says from 125℃ to 44A for TMCS1126x. Is TMCS112A1x-Q1 and TMCS112A7x-Q1 also 44A at 125℃? 

Q2)If it is the same, please recommend a device that can measure from 125℃ to 48A.

  • 0
    TI__Expert 7925 points

    Hello,

    Junehee Park said:
    Q2)If it is the same, please recommend a device that can measure from 125℃ to 48A.

    The TMCS1126x, the TMCS1123x, the TMCS1133x, and the TMCS1127x devices are all a part of the same family and share the same leadframe, so the thermal performance will be the same for all four devices. This is reflected by the SOA curve, which is the same on all 4 device datasheets:

    Junehee Park said:
    Q2)If it is the same, please recommend a device that can measure from 125℃ to 48A.

    This is our highest current in-package hall-based current sensor to date.

    The TMCS1126 thermal performance is based on a reference layout (the TMCS1126EVM), so if you create a better layout by having better heat dissipation on the input pins you will be able to operate the device at higher current levels than the datasheet curve above. Additionally, if the current you are trying to measure is not a constant current, you may be able to use higher current levels because breaks in the current input waveform give the device a chance to cool down.

    Let me know if you have any more questions about this,

    Levi DV

  • 0 in reply to Levi DV
    Intellectual 320 points

    Hi

    Additional Questions.

    1. What is the input noise(mArms) under these conditions?

        -at 500KHz, Ta 25℃, CL = 1nF

    2. What is the total output error %?

  • 0 in reply to Junehee Park
    TI__Expert 7925 points

    Hello,

    Junehee Park said:
    1. What is the input noise(mArms) under these conditions?

    The input noise will be about 140mA RMS. Please note that the load capacitor does not have any effect on this without a filter resistor.

    Junehee Park said:
    2. What is the total output error %?

    The total output error will depend on the input current level you are sensing. At 48A using the TMCS1126A7A the total error at 25°C will be 0.65%. This does not include the noise error, which will increase the error percentage to 0.71%.

    Let me know if you have any more questions,

    Levi DV

  • 0 in reply to Levi DV
    Intellectual 320 points

    Hi Levi DV~

    I want know Total output error.(-40~125)

    Please check.

  • 0 in reply to Junehee Park
    TI__Expert 7925 points

    Hello,

    Over temperature, the error will be 0.87%. The noise will not have a significant impact on this error. This can be calculated using the following formulas from section 9.1.1 of the datasheet:

    Let me know if you have any more questions,

    Levi DV