For my TB6600 motor design I had 5 x 1R, 1W, +/-5% resistors in parallel (making the effective resistance 0.2mR 0.2R) for current sensing. However, is it ok to use something like this for current sensing?

 

For my TB6600 motor design I had 5 x 1R, 1W, +/-5% resistors in parallel (making the effective resistance 0.2mR) for current sensing. However, is it ok to use something like this for current sensing?

Your calculation is off (or the communication of your result is in error).

5 X 1ohm in parallel is 0.2 ohm or 200 mOhm. You list 0.2mOhm.

The following is only a concern if you are working on a project with high sensitivity...
(Absolute measurement with Less than 1% error over whole temp range. If your system has feedback and self correcting, then not an issue.in general).
One concern is heating and change of resistance with temperature which can screw up a system. You can go for a higher attach current sense resistor to minimize the effect or a lower resistance (which lowers the dynamic range of voltage change) or make sure the resistor has a very low change of resistance per degree of temp change.



Good luck.

 

I use very similar resistors for current measurement and I imagine you can too.

 

Thanks folks! This helps.

 

There is also power Mosfets with extra pins that indicate the current through the device.
Max.

 

There is also power Mosfets with extra pins that indicate the current through the device.
Max.

Ah I see. So you are suggesting the use of Rds as a current sensing resistor?

 

Ah I see. So you are suggesting the use of Rds as a current sensing resistor?

No because Rds depends on gate voltage (and charge state of the gate since a MOSFET gate is a natural capacitor). Those MOSFETS have an onboard precision trimmed low ohm resistor. Some actually have an amplified output (if it is still in production) but I haven't looked at them in a long time.

 

No because Rds depends on gate voltage (and charge state of the gate since a MOSFET gate is a natural capacitor). Those MOSFETS have an onboard precision trimmed low ohm resistor. Some actually have an amplified output (if it is still in production) but I haven't looked at them in a long time.

This sounds very interesting. Can you suggest a few part numbers?

 

AND8093 - Current Sensing Power MOSFETs - ON Semiconductor