Datasheet

TMC2209 DATASHEET (Rev. 1.03 / 2019-JUN-26) 54
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vsense=1 allows a lower peak current setting of about 55% of the value yielded with vsense=0 (as
specified by V
SRTH
/ V
SRTL
).
In RDSon measurement mode, connect the BRA and BRB pins to GND using the shortest possible path
(i.e. shortest possible PCB path). 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 1.4A RMS current. The best results are
yielded with StealthChop operation in combination with RDSon based current sensing.
For most precise current control and for best results with SpreadCycle, it is recommended to use
external 1% sense resistors rather than RDSon based current control.