Thermal Characteristics
4
Thermal Characteristics
Table 4. MPC875/870 Thermal Resistance Data
Rating
Environment
Natural convection
Single-layer board (1s)
Four-layer board (2s2p)
Airflow (200 ft/min)
Single-layer board (1s)
Four-layer board (2s2p)
Symbol
R
θJA
2
R
θJMA
3
R
θJMA
R
θJMA
R
θJB
R
θJC
Natural convection
Airflow (200 ft/min)
Ψ
JT
Ψ
JT
Value
43
29
36
26
20
10
2
2
Unit
°C/W
shows the thermal characteristics for the MPC875/870.
Junction-to-ambient
1
Junction-to-board
4
Junction-to-case
5
Junction-to-package top
6
Junction temperature is a function of on-chip power dissipation, package thermal resistance, mounting site (board)
temperature, ambient temperature, airflow, 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.
3
Per JEDEC JESD51-6 with the board horizontal.
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.
5
Indicates the average thermal resistance between the die and the case top surface as measured by the cold plate
method (MIL SPEC-883 Method 1012.1) with the cold plate temperature used for the case temperature. For exposed
pad packages where the pad would be expected to be soldered, junction-to-case thermal resistance is a simulated
value from the junction to the exposed pad without contact resistance.
6
Thermal characterization parameter indicating the temperature difference between the package top and the junction
temperature per JEDEC JESD51-2.
1
5
Power Dissipation
Table 5. Power Dissipation (P
D
)
Die Revision
Bus
Mode
Frequency
66 MHz
1:1
0
2:1
80 MHz
133 MHz
Typical
1
310
350
430
Maximum
2
390
430
495
Unit
mW
mW
mW
provides information on power dissipation. The modes are 1:1, where CPU and bus speeds are
equal, and 2:1, where CPU frequency is twice bus speed.
1
Typical
power dissipation is measured at V
DDL
= V
DDSYN
= 1.8 V, and V
DDH
is at 3.3 V.
MPC875/MPC870 Hardware Specifications, Rev. 3.0
Freescale Semiconductor
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
9
FREESCALE [ FREESCALE SEMICONDUCTOR, INC ]
