where:
• R
θJA
= junction to ambient thermal resistance (°C/W)
• R
θJC
= junction to case thermal resistance (°C/W)
• R
θCA
= case to ambient thermal resistance (°C/W)
R
θJC
is device related and cannot be influenced by the user. The user controls the thermal
environment to change the case to ambient thermal resistance, R
θCA
. For instance, the
user can change the size of the heat sink, the air flow around the device, the interface
material, the mounting arrangement on printed circuit board, or change the thermal
dissipation on the printed circuit board surrounding the device.
To determine the junction temperature of the device in the application when heat sinks
are not used, the Thermal Characterization Parameter (Ψ
JT
) can be used to determine the
junction temperature with a measurement of the temperature at the top center of the
package case using this equation:
T
J
= T
T
+ (Ψ
JT
× P
D
)
where:
• T
T
= thermocouple temperature on top of the package (°C)
• Ψ
JT
= thermal characterization parameter (°C/W)
• P
D
= power dissipation in the package (W)
The thermal characterization parameter is measured per JESD51-2 specification using a
40 gauge type T thermocouple epoxied to the top center of the package case. The
thermocouple should be positioned so that the thermocouple junction rests on the
package. A small amount of epoxy is placed over the thermocouple junction and over
about 1 mm of wire extending from the junction. The thermocouple wire is placed flat
against the package case to avoid measurement errors caused by cooling effects of the
thermocouple wire.
21
Ordering information
Table 60. Ordering information
Part Number Device Type Flash/SRAM Emulation RAM Package Frequency
SPC5746RK1MMT5 Sample PD
1
4M / 256 KB - 252 MAPBGA 200 MHz
SPC5746RK1MLU3 Sample PD 4M/256KB - 176 LQFP 150 MHz
SPC5745RK1MMT5 Sample PD 3M/192KB - 252 MAPBGA 200 MHz
SPC5745RK1MLU3 Sample PD 3M / 192 KB - 176 LQFP 150 MHz
SPC5743RK1MLU5 Sample PD 2M / 128KB - 176 LQFP 200 MHz
SPC5743RK1MLQ5 Sample PD 2M / 128 KB - 144 LQFP 200 MHz
PPC5746R2K1MMZ5A Sample ED
2
4M / 256 KB 1 MB 292 MAPBGA 200 MHz
Ordering information
SPC5746R Microcontroller Data Sheet, Rev. 6, 06/2017
90 NXP Semiconductors
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