Datasheet

TMC2660 DATASHEET (Rev. 1.05 / 2016-JUL-14) 49
www.trinamic.com
16.3 Thermal Characteristics
Parameter
Symbol
Conditions
Typ
Unit
Thermal resistance bridge
transistor junction to ambient,
soldered to 4 layer 20cm² PCB
(or 20cm² size per driver IC for
multiple driver board)
R
THA14
one bridge chopping,
fixed polarity
80
K/W
R
THA24
two bridges chopping,
fixed polarity
50
K/W
R
THA44
Motor running
37
K/W
Thermal resistance bridge
transistor junction to ambient,
soldered to 4 layer 50cm² PCB
R
THA44a
Motor running
28
K/W
Power dissipation in power
bridge MOSFETs
(MOSFETs at 125°C)
24V, 30kHz chopper, fast slope
P
BRIDGES
2A RMS per coil
2.6
W
P
BRIDGES
2.2A RMS per coil
3.2
W
P
BRIDGES
2.8A RMS per coil
5.0
W
Additional power dissipation
from core
P
CORE
24V supply, 16MHz f
CLK
0.28
W
Especially when device is to be operated near its maximum thermal limits, care has to be taken to
provide a good thermal design of the PCB layout in order to avoid overheating of the power MOSFETs
integrated into the TMC2660. As the TMC2660 use discrete MOSFETs, power dissipation in each MOSFET
needs to be looked over carefully. The actual values depend on the duty cycle and the die
temperature. The thermal characteristics and the sample layout are intended as a guideline for your
own board layout. In case, the driver is to be operated at high current levels, special care should be
taken to spread the heat generated by the driver power bridges efficiently within the PCB.
Worst case power dissipation for the individual MOSFET is in standstill or at low velocity, with one
coil operating at the maximum current, because one full bridge in this case takes over the full current.
This scenario can be avoided with power down current reduction and current reduction in case slow
movements are required. As the single MOSFET temperatures cannot be monitored within the system,
it is a good practice to react to the temperature pre-warning by reducing motor current, rather than
relying on the overtemperature switch off.
The MOSFET and bond wire temperature should not exceed 150°C, despite temperatures up to 200°C
will not immediately destroy the devices. But the package plastics will apply strain onto the bond
wires, so that cyclic, repetitive exposure to temperatures above 150°C may damage the electrical
contacts and increase contact resistance and eventually lead to contract break.
Check MOSFET temperature under worst case conditions not to exceed 150°C using a thermal camera
to validate your layout. Please carefully check your layout against the sample layout or the layout of
the TMC2660-Evaluation board on the TRINAMIC website in order to ensure proper cooling of the IC!
Figure 16.1 TMC2660 operating at 2.3A RMS (3.2A peak) on a 50cm² sized board