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HE100 level shifter circuit

Hi,

I want to measure current of 0-50A. For that, in my application I am using HE100T01 hall effect sensor which can measure current from -100A to +100A(depending on the direction of flow it gives -ve and +ve values). The Hall effect sensor gives a current output of -50mA to +50mA. Since my micro controller ADC can't measure negative voltage, I tried level shifting the sensor output to positive region using the circuit which is attached. But the negative voltage is not properly clamping to the +2.5V offset. Can anyone please help me to identify the problem and also give any alternate circuitry to convert the sensor output which can be measured using a micro controller ADC?

Please find the datasheet for the Hall effect sensor and attached schematic. http://www.electrohms.com/data_pdf/2_1_HE100T01-05.pdf

Looking forward for earlier responses.

Regards,
Vishnu

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  • \$\begingroup\$ If your running a simulator, is C1 shorted? (see diagram) \$\endgroup\$
    – Nedd
    Nov 21 '15 at 13:42
  • \$\begingroup\$ Thanks for the response. Its just a rough drawing of my circuit and it is already on the board. C1 is not shorted. its just a drawing mistake. \$\endgroup\$
    – Vishnu.P
    Nov 22 '15 at 14:45
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On most op-amps you cannot properly use an input signal that is below the - supply pin. You might try to bias the sensor output to 2.5v (with equal pull up and pull down resistors on the sensor's output).

Alternately, to set up a true level shifting circuit see these examples that use hall effect sensors:

http://www.next.gr/sens-detectors/hall-effect/current-monitor-l13368.html

http://www.instructables.com/id/How-to-Measure-AC-Current-using-Hall-Effect-Sensor/

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  • \$\begingroup\$ Thanks a lot for the response. I'll try connecting as you suggested and let you know. I am currently using a 30E as burden resistor. Of what order of resistor value should I choose to bias the sensor output to 2.V? \$\endgroup\$
    – Vishnu.P
    Nov 22 '15 at 14:49

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