TMC2100 DATASHEET (Rev. 1.09 / 2018-OCT-10)
11
4 Suggestions for Layout
The sample circuits show the connection of external components in different operation and supply
modes.
4.1 Basic Hints for Power Supply
Use low ESR capacitors for filtering the power supply which are capable to cope with the current
ripple. The current ripple often depends on the power supply and cable length. The VCC_IO voltage
can be supplied from 5VOUT, or from an external source, e.g. a low drop 3.3V regulator. In order to
minimize linear voltage regulator power dissipation of the internal 5V voltage regulator in
applications where VM is high, a different (lower) supply voltage can be used for VSA, if available. For
example, many applications provide a 12V supply in addition to a higher supply voltage, like 24V or
36V. Using the 12V supply for VSA will reduce the power dissipation of the internal 5V regulator to
about 37% resp. 23% of the dissipation caused by supply with the full motor voltage.
Basic Layout Hints
Place sense resistors and all filter capacitors as close as possible to the related IC pins. Use a solid
common GND for all GND connections, also for sense resistor GND. Connect 5VOUT filtering capacitor
directly to 5VOUT and GNDA pin. See layout hints for more details. Low ESR electrolytic capacitors are
recommended for VS filtering.
Attention
In case VSA is supplied by a different voltage source, make sure that VSA does not exceed VS by
more than one diode drop upon power up or power down.
4.2 Reduced Number of Components
Optional use lower
voltage down to 6V
+VM
VSA
5V Voltage
5VOUT
VCC
regulator
100n
4.7µ
Figure 4.1 Reduced number of filtering components
The standard application circuit uses RC filtering to de-couple the output of the internal linear
regulator from high frequency ripple caused by digital circuitry supplied by the VCC input. For cost
sensitive applications, the RC-filtering on VCC can be eliminated. This leads to more noise on 5VOUT
caused by operation of the charge pump and the internal digital circuitry. There is a slight impact on
microstep vibration and chopper noise performance.
4.3 Internal Current Sensing
For cost critical or space limited applications, it may be desired to eliminate the sense resistors. The
TMC2100 allows using the resistance of the internal MOSFETs as a sense resistor. Further, this slightly
reduces power dissipation, because the effective resistance of the driver bridge is reduced. In this
application, a reference current set by a tiny external resistor programs the output current. For
calculation of the reference resistor, refer chapter 9.
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