Thermal Characteristics
4 Thermal Characteristics
Table 4 shows the thermal characteristics for the MPC885/880.
Table 4. MPC885/880 Thermal Resistance Data
Environment
Single-layer board (1s)
Rating
Symbol
Value
Unit
2
Junction-to-ambient 1
Natural convection
RθJA
37
25
30
22
17
10
2
°C/W
3
Four-layer board (2s2p)
Single-layer board (1s)
Four-layer board (2s2p)
RθJMA
3
Airflow (200 ft/min)
RθJMA
3
RθJMA
Junction-to-board 4
RθJB
RθJC
ΨJT
5
Junction-to-case
Junction-to-package top 6
Natural convection
Airflow (200 ft/min)
ΨJT
2
1 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 package top and the junction
temperature per JEDEC JESD51-2.
5 Power Dissipation
Table 5 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.
Table 5. Power Dissipation (PD)
Bus
Mode
CPU
Frequency
Die Revision
Typical 1
Maximum 2
Unit
66 MHz
80 MHz
133 MHz
310
350
430
390
430
495
mW
mW
mW
1:1
2:1
0
1 Typical power dissipation at VDDL = VDDSYN = 1.8 V, and VDDH is at 3.3 V.
MPC885/MPC880 Hardware Specifications, Rev. 3
10
Freescale Semiconductor
FREESCALE [ Freescale ]
