Datasheet
TMC2041 DATASHEET (Rev. 1.02 / 2017-MAY-16) 59
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18.3 Thermal Characteristics
The following table shall give an idea on the thermal resistance of the QFN-48 package. The thermal
resistance for a four layer board will provide a good idea on a typical application. The single layer
board example is kind of a worst case condition, as the typical application will require a 4 layer
board. Actual thermal characteristics will depend on the PCB layout, PCB type and PCB size.
A thermal resistance of 23°C/W for a typical board means, that the package is capable of continuously
dissipating 4W at an ambient temperature of 25°C with the die temperature staying below 125°C.
Parameter
Symbol
Conditions
Typ
Unit
Typical power dissipation
One motor active, one motor in
standby at low current
P
D
One motor 1.00A RMS 115°C (125°C)
One motor 0.71A RMS 85°C (93°C)
Surface temperature at package center
(peak surface temperature), board
55mm x 85mm, 25°C environment
spreadCycle, sinewave, 40 or 20kHz
chopper, 24V, 16MHz, internal supply
for VCC
Motors: QSH4218-035-10-027
3.7
2.4
W
W
Typical power dissipation
Two motors active
P
D
Two motors 0.71A RMS 113°C (119°C)
Two motors 0.35A RMS 64°C (68°C)
3.7
1.4
W
W
Thermal resistance junction to
ambient on a single layer board
R
TJA
Single signal layer board (1s) as
defined in JEDEC EIA JESD51-3
(FR4, 76.2mm x 114.3mm, d=1.6mm)
80
K/W
Thermal resistance junction to
ambient on a multilayer board
R
TMJA
Dual signal and two internal power
plane board (2s2p) as defined in
JEDEC EIA JESD51-5 and JESD51-7
(FR4, 76.2mm x 114.3mm, d=1.6mm)
23
K/W
Thermal resistance junction to
ambient on a multilayer board
with air flow
R
TMJA1
Identical to R
TMJA
, but with air flow
1m/s
20
K/W
Thermal resistance junction to
board
R
TJB
PCB temperature measured within
1mm distance to the package
10
K/W
Thermal resistance junction to
case
R
TJC
Junction temperature to heat slug of
package
3
K/W
The thermal resistance in an actual layout can be tested by checking for the heat up caused by the
standby power consumption of the chip. When no motor is attached, all power seen on the power
supply is dissipated within the chip.
Note
A spread-sheet for calculating TMC2041 power dissipation is available on www.trinamic.com.