TMC260 and TMC261 DATASHEET (Rev. 2.05 / 2012-NOV-05)
4
1
Principles of Operation
0A+
High-Level
Interface
µC
S/D
TMC260
TMC261
0A-
0B+
0B-
S
N
SPI
TMC429
High-Level
Interface
0A+
S/D
µC
SPI
Motion
Controller
for up to
3 Motors
SPI
TMC260
TMC261
0A-
0B+
0B-
S
N
Figure 1.1 applications block diagram
The TMC260 and the TMC261 motor driver chips with included MOSFETs are 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 TMC260/TMC261. 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 TMC260/TMC261 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 TMC260/261 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 TMC260/TMC261 and TMC429 through the
SPI bus.
1.1
Key Concepts
The TMC260 and TMC261 motor drivers implement 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™
coolStep™
spreadCycle™
microPlyer™
High-precision load measurement using the back EMF on the coils
Load-adaptive current control which reduces energy consumption by as much as
75%
High-precision chopper algorithm available as an alternative to the traditional
constant off-time algorithm
Microstep interpolator for obtaining increased smoothness of microstepping over a
STEP/DIR interface
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TRINAMIC [ TRINAMIC MOTION CONTROL GMBH & CO. KG. ]
