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motor current sensing

senmeis

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Hi,

as far as I know the motor current can be measured with integrated current sense chip (current mirror + 0402 sense resistor) or external 2512 shunt resistor. Is the current for sense resistor only a few percentages of the one for shunt resistor?
 

FvM

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You are asking about AC or DC motor, current and voltage range? Which "integrated current sense chip" (manufacturer, type)?
 

KlausST

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Hi
Is the current for sense resistor only a few percentages of the one for shunt resistor?
A shunt resistor for current measurement is a series resistor. All parts in series take the same, full current.

If you have any special circuit in mind, then provide a schematic.

Klaus
 

senmeis

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In the attachment two TI circuits with shunt or sense resistors are shown.


current_sense.jpg
 

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You are asking for the scaling of internal current sensing. It depends on the motor driver current range, the answer is in the data sheet. For the mentioned TI drivers the monitor current scaling is 0.1 % and less.
 

KlausST

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Hi,

The shown circuits are combined "driver including current sense" ICs.
I don´t know which one you use.
Do you expect us to guess what exact IC you (want to) use?

From what I can see.
* the left schematic shows internal current measurement. No (acessable) motor current shunt is used.
* the right schematic shows external current measurement. the shunt carries the full motor current when motor is switched ON.

Maybe you already have a driver IC, then tell us which one.
Maybe you already have a current measurement IC, then tell us which one.
Maybe you read a document (where the pictures are from), then give a link to it.

Klaus
 

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