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Typical Application Circuit

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Shunt Resistor

(Previous research based on 75A max current)

  • Resistance of 0.0005 ohms to minimize losses

  • At max current of 75A, the resistor will dissipate 2.8W. To prevent overheating, a nonstandard resistor with a resistance of 0.0005 ohms and a power rating of 8W is selected

https://www.digikey.ca/en/products/detail/koa-speer-electronics-inc/PSL2NTEBL500F/1039674

Given the high current requirement of 150A, consider using multiple shunt resistors in parallel to spread out the power dissipation across multiple resistors.

Single Shunt Resistor

Multiple Shunt Resistors in Parallel

Pros

  • Simpler PCB layout

  • Takes up less board space

  • Spreading the current across multiple resistors would make it easier for them to handle the 150A current

Cons

  • Single resistor needs to be able to handle 150A current

  • Limited to very few options for component selection

  • Potentially more complicated PCB layout

  • Takes up more board space

  • Reduces accuracy of current measurement since the resistance of each resistor varies within the manufacturer’s tolerance

The selected shunt resistor is 0.0002 ohms and rated for 15W. At max current, the power dissipated is 1502 * 0.0002 = 4.5W. The safety margin is over 3x, so it should be safe to use only a single shunt resistor.

https://www.digikey.ca/en/products/detail/eaton-electronics-division/CHSA5930R0002F/16712930

NOTE: The INA228 has two options for the differential input voltage range, ±163.84 mV and ±40.96 mV. Since we are using a very small resistance, the max Vshunt is expected to be 150 * 0.0002 = 30mV. To obtain a higher resolution, the differential input voltage range should be set to ±40.96 mV. This is done by setting the ADCRANGE bit in the CONFIG register to 1.

Pullup Resistors x3

https://www.digikey.ca/en/products/detail/yageo/RC0603JR-1010KL/13694233

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