Datasheet

TMC5041 DATASHEET (Rev. 1.13 / 2017-MAY-16) 55
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Torque for VSTART
Torque available for
AMAX
Torque available for acceleration A1
Torque required
for static loads
torque
velocity [RPM]
0
M
FRICT
M
MAX
VMAX
M
FRICT
Portion of torque required for friction and static load within the system
M
MAX
Motor pull-out torque at v=0
motor torque
M
NOM2
high acceleration
reduced accel.
V1
M
NOM1
M
NOM1/2
Torque available at V1 resp. VMAX
Motor torque used in acceleration phase
high deceleration
reduced decel.
2xM
FRICT
Overall torque usable for deceleration
VSTART
Figure 10.2 Illustration of optimized motor torque usage with TMC5041 ramp generator
10.2.3 Velocity Mode
For the ease of use, velocity mode movements do not use the different acceleration and deceleration
settings. You need to set VMAX and AMAX only for velocity mode. The ramp generator always uses
AMAX to accelerate or decelerate to VMAX in this mode.
In order to decelerate the motor to stand still, it is sufficient to set VMAX to zero. The flag vzero
signals standstill of the motor. The flag velocity_reached always signals, that the target velocity has
been reached.
10.2.4 Early Ramp Termination
In cases where users can interact with a system, some applications require terminating a motion by
ramping down to zero velocity before the target position has been reached.
OPTIONS TO TERMINATE MOTION USING ACCELERATION SETTINGS:
a) Switch to velocity mode, set VMAX=0 and AMAX to the desired deceleration value. This will stop
the motor using a linear ramp.
b) For a stop in positioning mode, set VSTART=0 and VMAX=0. VSTOP is not used in this case. The
driver will use AMAX and A1 (as determined by V1) for going to zero velocity.
c) For a stop using D1, DMAX and VSTOP, trigger the deceleration phase by copying XACTUAL to
XTARGET. Set TZEROWAIT sufficiently to allow the CPU to interact during this time. The driver will
decelerate and eventually come to a stop. Poll the actual velocity to terminate motion during
TZEROWAIT time using option a) or b).
d) Activate a stop switch. This can be done by means of the hardware input, e.g. using a wired 'OR'
to the REF switch input. If you do not use the hardware input and have tied the REFL and REFR to
a fixed level, enable the stop function (stop_l_enable, stop_r_enable) and use the inverting
function (pol_stop_l, pol_stop_r) to simulate the switch activation.
10.2.5 Application Example: Joystick Control
Applications like surveillance cameras can be optimally enhanced using the motion controller: while
joystick commands operate the motor at a user defined velocity, the target ramp generator ensures
that the valid motion range never is left.