TMC262 DATASHEET (Rev. 2.07 / 2013-FEB-14)
4
1 Principles of Operation
0A+
0A-
N
MOSFET
S/D
High-Level
Interface
S
µC
µC
TMC262
Driver
Stage
0B+
0B-
SPI
0A+
0A-
TMC429
Motion
Controller
for up to
3 Motors
N
MOSFET
Driver
Stage
S/D
SPI
High-Level
Interface
S
TMC262
0B+
0B-
SPI
Figure 1.1 Applications block diagrams
The TMC262 motor driver is the intelligence between a motion controller and the power MOSFETs for
driving a 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 TMC262. 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 TMC262 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 TMC262 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 TMC262 and TMC429 through the SPI
bus.
1.1 Key Concepts
The TMC262 motor driver implements several advanced patented 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™
High-precision load measurement using the back EMF on the coils
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
www.trinamic.com
TRINAMIC [ TRINAMIC MOTION CONTROL GMBH & CO. KG. ]
