Author Topic: [Q] INA226 and low-side current sensing  (Read 1118 times)

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Offline AlxDroidDev

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[Q] INA226 and low-side current sensing
« on: January 30, 2016, 03:45:27 am »
For my electronic load project, I decided to use a Texas' INA226. If I went with the INA219 (high-side only), I'd have to use 2 shunt resistors: one, high-side, for the INA219, and another one, low side, for the opamp's feedback. Plus the INA219 is limited to 26V, and I'd like to go up to 30V.

1) Using the INA226, I can share the same shunt resistor for the INA226 and the opamp feedback, correct?

2) If I understood the INA226 datasheet correctly, when used on the low-side, it must be the last device in the current loop before ground. Is that correct? Is so, it means I cannot use this project as a constant current source for other devices that I'd connect after the load, such as a battery I wish to charge or a LED I wish to test.

3) Does the VBUS pin always have to be connected to the Vin pin? Can I connect the VBUS pin to the high side of the load, before the FET?

thank you!
« Last Edit: January 30, 2016, 03:47:41 am by AlxDroidDev »
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Offline Kleinstein

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Re: [Q] INA226 and low-side current sensing
« Reply #1 on: January 30, 2016, 04:31:24 am »
The INA226 can measure two voltages, a smaller one between the two inputs for the shunt and a second one between GND and VBus. Its is up to you to decide where to have the inputs. The main thing is to have less than 36 V at any input relative to GND. So the shut can be high side or low side or somewhere in the middle if you like and have two loads in series. So if a 30 V outout is planed the raw voltage before regulation might be to high under wirst case conditions.

 
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Offline AlxDroidDev

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Re: [Q] INA226 and low-side current sensing
« Reply #2 on: February 03, 2016, 08:57:51 am »
The INA226 can measure two voltages, a smaller one between the two inputs for the shunt and a second one between GND and VBus. Its is up to you to decide where to have the inputs. The main thing is to have less than 36 V at any input relative to GND. So the shut can be high side or low side or somewhere in the middle if you like and have two loads in series. So if a 30 V outout is planed the raw voltage before regulation might be to high under wirst case conditions.

Vielen Dank!
"The nice thing about standards is that you have so many to choose from." (Andrew S. Tanenbaum)
 


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