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TMAG5170: Magnetic field measurements

Gerald
Genius 9570 points
Part Number: TMAG5170
Other Parts Discussed in Thread: DRV5057,

Hi Team,

May I ask for help? Our customer is looking for a sensor able to measure both DC and AC magnetic fields (AC in range of 3 to 300Hz or higher).
He need the sensor to have a digital output (SPI/I2C) because the device they are working on will have no analog interface. 

I saw this E2E post: https://e2e.ti.com/support/sensors-group/sensors/f/sensors-forum/820307/how-to-measure-electro-magnetic-field
then ask the customer if DRV5057 can be considered since the device produces a pulse-width modulated digital signal output.

But the point is that our customer need some I2C/SPI output sensor because it is the available interface for the device they will be connecting the sensor.
That bring us to checking TMAG5170. Will it be enough for our customer project? Will it be able to measure AC magnetic fields up to 300Hz or higher?
If not, do you know a device that can fit our customer requirements? We hope to receive you confirmation/advise. Thank you so much.

Kind regards,
Gerald


  • +1
    TI__Mastermind 21060 points

    Gerald,

    TMAG5170 is capable of performing measurements of the magnetic field for changing magnetic fields.  One of the primary functions is to use a rotating magnet which will produce sine/cosine inputs that it can use for angle calculations.  It will sense the composite field for any conversion cycle.

    When performing these measurements, the device does so serially (X-Y-Z-X-Y-Z), and requires 45 us for the first conversion and each subsequent conversion in the pipeline would require 25 us.  So in continuous mode, a minimum sample time for all three axes is 75 us.  As a result, we could achieve the minimum sample time for signals up to about 6 kHz.  However, it is important to remember the input referred noise relative to the expected input field.  If too high, then oversampling would be required which allows the device to average.  Supposing 16x averaging were enabled, then the new sample time would be approximately 1.2 ms and the device should be just above the minimum sample rate for an 400 Hz signal. 

    If only one or two components are needed, then the averaging could be increased up to 32x.  

    As a reference please note the noise specification here:

    Thanks,

    Scott