Datasheet

TMC220X, TMC222X DATASHEET (Rev. 1.02 / 2017-MAY-16) 74
www.trinamic.com
19 Layout Considerations
19.1 Exposed Die Pad
The TMC22xx uses its die attach pad to dissipate heat from the drivers and the linear regulator to the
board. For best electrical and thermal performance, use a reasonable amount of solid, thermally
conducting vias between the die attach pad and the ground plane. The printed circuit board should
have a solid ground plane spreading heat into the board and providing for a stable GND reference.
19.2 Wiring GND
All signals of the TMC22xx are referenced to their respective GND. Directly connect all GND pins under
the device to a common ground area (GND and die attach pad). The GND plane right below the die
attach pad should be treated as a virtual star point. For thermal reasons, the PCB top layer shall be
connected to a large PCB GND plane spreading heat within the PCB.
Attention
Especially the sense resistors are susceptible to GND differences and GND ripple voltage, as the
microstep current steps make up for voltages down to 0.5 mV. No current other than the sense
resistor current should flow on their connections to GND and to the TMC22xx. Optimally place them
close to the IC, with one or more vias to the GND plane for each sense resistor. The two sense
resistors for one coil should not share a common ground connection trace or vias, as also PCB traces
have a certain resistance.
19.3 Supply Filtering
The 5VOUT output voltage ceramic filtering capacitor (2.2 to 4.7 µF recommended) should be placed as
close as possible to the 5VOUT pin, with its GND return going directly to the die pad or the nearest
GND pin. This ground connection shall not be shared with other loads or additional vias to the GND
plane. Use as short and as thick connections as possible.
The motor supply pins VS should be decoupled with an electrolytic capacitor (47 μF or larger is
recommended) and a ceramic capacitor, placed close to the device.
Take into account that the switching motor coil outputs have a high dV/dt. Thus capacitive stray into
high resistive signals can occur, if the motor traces are near other traces over longer distances.