NXP Semiconductors MPC5777M - Thermal characteristics

Electrical characteristics
MPC5777M Microcontroller Data Sheet, Rev. 6
NXP Semiconductors 131
3.20 Thermal characteristics
The following tables describe the thermal characteristics of the device.
.
3.20.1 General notes for specifications at maximum junction temperature
An estimation of the chip junction temperature, T
J
, can be obtained from the equation:
T
J
= T
A
+ (R
JA
* P
D
) Eqn. 1
where:
T
A
= ambient temperature for the package (
o
C)
R
JA
= junction-to-ambient thermal resistance (
o
C/W)
P
D
= power dissipation in the package (W)
The thermal resistance values used are based on the JEDEC JESD51 series of standards to provide consistent values for
estimations and comparisons. The difference between the values determined for the single-layer (1s) board compared to a
four-layer board that has two signal layers, a power and a ground plane (2s2p), demonstrate that the effective thermal resistance
is not a constant. The thermal resistance depends on the:
Table 74. Thermal characteristics
Symbol Parameter Conditions
416
Value
512
Value
Unit Notes
R
JA
Junction-to-Ambient, Natural
Convection
Single Layer board (1s) 25 24.1 °C/W
1,2
1
Junction temperature is a function of die size, on-chip power dissipation, package thermal resistance,
mounting site (board) temperature, ambient temperature, air flow, power dissipation of other components on
the board, and board thermal resistance.
2
Per SEMI G38-87 and JEDEC JESD51-2 with the single layer board horizontal.
Four layer board (2s2p) 17.2 16.8
1,2,3
3
Per JEDEC JESD51-6 with the board horizontal.
R
JMA
Junction-to-Moving-Air, Ambient @200 ft/min., single layer
board (1s)
18.1 16.6 °C/W
1,3
@200 ft/min., four layer board
(2s2p)
13.4 12.4
1,3
R
JB
Junction-to-board — 8.6 8.8 °C/W
4
4
Thermal resistance between the die and the printed circuit board per JEDEC JESD51-8. Board temperature is
measured on the top surface of the board near the package.
R
JC
Junction-to-case — 5.0 5.0 °C/W
5
5
Thermal resistance between the die and the case top surface as measured by the cold plate method (MIL
SPEC-883 Method 1012.1).

JT
Junction-to-package top Natural convection 0.2 0.2 °C/W
6
6
Thermal characterization parameter indicating the temperature difference between package top and the
junction temperature per JEDEC JESD51-2.

JB
Junction-to-package bottom/solder
balls
Natural convection 3.5 3.0 °C/W
7
7
Thermal characterization parameter indicating the temperature difference between package bottom center and
the junction temperature per JEDEC JESD51-12.