Datasheet

TMC2209 DATASHEET (Rev. 1.03 / 2019-JUN-26) 7
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best settings during the first motion after power up and further optimizes the settings in subsequent
motions. An initial homing sequence is sufficient for learning. Optionally, initial learning parameters
can be stored to OTP. StealthChop2 allows high motor dynamics, by reacting at once to a change of
motor velocity.
For highest velocity applications, SpreadCycle is an option to StealthChop2. It can be enabled via
input pin or via UART and OTP. StealthChop2 and SpreadCycle may even be used in a combined
configuration for the best of both worlds: StealthChop2 for no-noise stand still, silent and smooth
performance, SpreadCycle at higher velocity for high dynamics and highest peak velocity at low
vibration.
SpreadCycle is an advanced cycle-by-cycle chopper mode. It offers smooth operation and good
resonance dampening over a wide range of speed and load. The SpreadCycle chopper scheme
automatically integrates and tunes fast decay cycles to guarantee smooth zero crossing performance.
Benefits of using StealthChop2:
- Significantly improved microstepping with low cost motors
- Motor runs smooth and quiet
- Absolutely no standby noise
- Reduced mechanical resonance yields improved torque
1.5 StallGuard4 – Mechanical Load Sensing
StallGuard4 provides an accurate measurement of the load on the motor. It can be used for stall
detection as well as other uses at loads below those which stall the motor, such as CoolStep load-
adaptive current reduction. This gives more information on the drive allowing functions like
sensorless homing and diagnostics of the drive mechanics.
1.6 CoolStep – Load Adaptive Current Control
coolStep drives the motor at the optimum current. It uses the stallGuard4 load measurement
information to adjust the motor current to the minimum amount required in the actual load situation.
This saves energy and keeps the components cool.
Benefits are:
- Energy efficiency power consumption decreased up to 75%
- Motor generates less heat improved mechanical precision
- Less or no cooling improved reliability
- Use of smaller motor less torque reserve required → cheaper motor does the job
- Less motor noise Due to less energy exciting motor resonances
Figure 1.3 shows the efficiency gain of a 42mm stepper motor when using coolStep compared to
standard operation with 50% of torque reserve. coolStep is enabled above 60RPM in the example.
0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
0 50 100 150 200 250 300 350
Efficiency
Velocity [RPM]
Efficiency with coolStep
Efficiency with 50% torque reserve
Figure 1.3 Energy efficiency with coolStep (example)