TMC4671 Datasheet • IC Version V1.00 | Document Revision V1.04 • 2018-Dec-11
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Figure 19: Hall Sensor Angles
Hall sensors give absolute positions within an electrical period with a resolution of 60
°
as 16 bit positions
(s16 resp. u16) PHI. With activated interim Hall position interpolation, the user gets high resolution interim
positions when the motor is running at a speed above 60 rpm.
4.7.5 Digital Hall Sensor - Interim Position Interpolation
For lower torque ripple the user can switch on the position interpolation of interim Hall positions. This
function is useful for motors that are compatible with sine wave commutation, but equipped with digital
Hall sensors.
When the position interpolation is switched on, it becomes active on speeds above 60 rpm. For lower
speeds it automatically disables itself. This is especially important when the motor has to be at rest.
Hall sensor position interpolation might fail when Hall sensors are not properly placed in the motor. Please
adjust Hall sensor positions for this case.
4.7.6 Digital Hall Sensors - Masking and Filtering
Sometimes digital Hall sensor signals get disturbed by switching events in the power stage. The TMC4671
can automatically mask switching distortions by correct setting of the HALL_MASKING register. When a
switching event occurs, the Hall sensor signals are held for HALL_MASKING value times 10 ns. This way,
Hall sensor distortions are eliminated.
Uncorrelated distortions can be filtered via a digital filter of configurable length. If the input signal to the
filter does not change for HALL_DIG_FILTER_LENGTH times 5 us, the signal can pass the filter. This filter
eliminates issues with bouncing Hall signals.
4.7.7 Digital Hall Sensors together with Incremental Encoder
If a motor is equipped with both Hall sensors and incremental encoder, the Hall sensors can be used for
the initialization as a low resolution absolute position sensor. Later on, the incremental encoder can be
used as a high resolution sensor for commutation.
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