TMC2100 DATASHEET (Rev. 1.07 / 2017-MAY-15)
27
In RDSon measurement mode, connect the BRA and BRB pins to GND using the shortest possible path
(i.e. lowest possible PCB resistance). RDSon based measurement gives best results when combined
with stealthChop. When using spreadCycle with RDSon based current measurement, slightly
asymmetric current measurement for positive currents (on phase) and negative currents (fast decay
phase) may result in chopper noise. This especially occurs at high die temperature and increased
motor current.
Note
The absolute current levels achieved with RDSon based current sensing may depend on PCB layout
exactly like with external sense resistors, because trace resistance on BR pins will add to the effective
sense resistance. Therefore we recommend to measure and calibrate the current setting within the
application.
Thumb rule
RDSon based current sensing works best for motors with up to 1A RMS current. The best results are
yielded with stealthChop operation in combination with RDSon based current sensing.
For most precise current control and best results with spreadCycle, it is recommended to use external
1% sense resistors rather than RDSon based current control.
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TRINAMIC [ TRINAMIC MOTION CONTROL GMBH & CO. KG. ]
