Datasheet

TMC2660 DATASHEET (Rev. 1.05 / 2016-JUL-14) 4
www.trinamic.com
1 Principles of Operation
µC
SPI
S/D
High-Level
Interface
N
S
0A+
0A-
0B+
TMC2660
0B-
µC
SPI
SPI
S/D
TMC429
Motion
Controller
for up to
3 Motors
High-Level
Interface
N
S
0A+
0A-
0B+
TMC2660
0B-
Figure 1.1 Block diagram: applications
The TMC2660 motor driver chip with included MOSFETs is the intelligence and power between a
motion controller and the two phase stepper motor as shown in Figure 1.1. Following power-up, an
embedded microcontroller initializes the driver by sending commands over an SPI bus to write
control parameters and mode bits in the TMC2660. The microcontroller may implement the motion-
control function as shown in the upper part of the figure, or it may send commands to a dedicated
motion controller chip such as TRINAMIC’s TMC429 as shown in the lower part.
The motion controller can control the motor position by sending pulses on the STEP signal while
indicating the direction on the DIR signal. The TMC2660 has a microstep counter and sine table to
convert these signals into the coil currents which control the position of the motor. If the
microcontroller implements the motion-control function, it can write values for the coil currents
directly to the TMC2660 over the SPI interface, in which case the STEP/DIR interface may be disabled.
This mode of operation requires software to track the motor position and reference a sine table to
calculate the coil currents.
To optimize power consumption and heat dissipation, software may also adjust coolStep and
stallGuard2 parameters in real-time, for example to implement different tradeoffs between speed and
power consumption in different modes of operation.
The motion control function is a hard real-time task which may be a burden to implement reliably
alongside other tasks on the embedded microcontroller. By offloading the motion-control function to
the TMC429, up to three motors can be operated reliably with very little demand for service from the
microcontroller. Software only needs to send target positions, and the TMC429 generates precisely
timed step pulses. Software retains full control over both the TMC2660 and TMC429 through the SPI
bus.
1.1 Key Concepts
The TMC2660 motor driver implements several advanced features which are exclusive to TRINAMIC
products. These features contribute toward greater precision, greater energy efficiency, higher
reliability, smoother motion, and cooler operation in many stepper motor applications.
stallGuard2™ High-precision load measurement using the back EMF on the coils
coolStep™ Load-adaptive current control which reduces energy consumption by as much as
75%
spreadCycle™ High-precision chopper algorithm available as an alternative to the traditional
constant off-time algorithm
microPlyer™ Microstep interpolator for obtaining increased smoothness of microstepping over a
STEP/DIR interface