Tool/software:
Hi,
Customer and I have few question about the parameters of TMAG5170.
In TMAG5170, Customer need the resolution larger than 15bit, this is the SPI resolution or ADC resolution?
Could the total sensitivity error of TMAG5170 can achieve absolution accuracy of +-0.1?
Could the SPI support 3-line and 4-line setting at the same time?
Thank you,
Yishan CHen
Yishan,
The internal ADC of TMAG5170 has 12 bit resolution. When over-sampling (averaging) is enabled the output gets extended to 16 bits. The ENOB for the result scales based on the amount of averaging applied, and I believe at the maximum 32x averaging the effective result is approximately 14.5 bits.
The absolute accuracy of +/- 0.1 does not specify units, so it is unclear what is meant. At 32x averaging, the RMS noise of the sensor is about 34µT. This is approximately a 1 sigma value, so if we extrapolate this to 6 sigma, the peak noise should be about 200µT. For angle accuracy, the problem becomes a more complex combination of factors across mechanical tolerances, sensor specification, and temperature. Room temp plots calibrated to the mechanical error are found in the datasheet:
For linear motion, there is a TI design which demonstrates measuring linear travel to about +/-0.15um of accuracy
https://www.ti.com/tool/TIDA-060045
The SPI require 4 wires: Clock, Chip Select, Serial Data In, and Serial Data Out. It is required to program the device initially using Serial Data In, so it would not be possible to remove this connection. You could, however, gang 3 or 4 devices to the same bus to take measurements. You would just need to be able to control Chip Select appropriately to communicate with each serially. To take accurate and simultaneous measurements it is recommended to put the device in trigger mode and then share connections on the ALERT pin to align conversion start times. This is described in the TI design above.
Thanks,
Scott
