ADR8211 Current measurment for motor driving

I have asked this iisue earlier but again.

Where is mistake?

20 ohm Resistor between v+  and shunt or  between V-  and shunt could be damaged.

We are checking motor drive current by AD8211. Motor VCC  24V and GND (GND_Motor) is filtteres (Emifilter)

AD8211: V+ is connected 5V_CTRL (using cap 100nF / GND CTRL ) AD8211 GND is connected GND_CTRL.

Shunt resistor is 0.01ohm. Between Vin+ and Vin- line is Cap 1uF serial resitor foe both Vin+ and Vin- are 20ohm .

could GND of AD8211 be connected to the GND_Motor or GND_CTRL?

    • Now i found same problem again and seems that  AD8211 is damaged and output voltage is too much, close to 5v

Those 20 ohm resistors were damaged as well. I changed resistors but output voltage was still too high.Seems that  New Ad8211 helps, Reference voltage ls 3.3V in controller.

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    •  Analog Employees 
    on Jan 31, 2019 4:32 PM

    Hi,

    Can you measure the voltage difference between GND_Motor and GND_CTRL? If GND_CTRL is a few volts different than the GND_Motor at any point, this could provide a path for unexpected current to flow through the 20ohm resistors and the AD8211.

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  • 0
    •  Analog Employees 
    on Jan 31, 2019 4:32 PM

    Hi,

    Can you measure the voltage difference between GND_Motor and GND_CTRL? If GND_CTRL is a few volts different than the GND_Motor at any point, this could provide a path for unexpected current to flow through the 20ohm resistors and the AD8211.

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