Electrical Characteristics
16 Thermal resistance between the die and the printed circuit board in conformance with JEDEC JESD51-8. Board
temperature is measured on the top surface of the board near the package.
17 Thermal resistance between the die and the case top surface as measured by the cold plate method (MIL SPEC-883
Method 1012.1).
18 Thermal characterization parameter indicating the temperature difference between package top and the junction
temperature per JEDEC JESD51-2. When Greek letters are not available, the thermal characterization parameter is written
in conformance with Psi-JT.
The average chip-junction temperature (TJ) in °C can be obtained from:
(1)
)
TJ = TA + (PD × ΘJMA
Where:
TA
= ambient temperature, °C
ΘJA
PD
= package thermal resistance, junction-to-ambient, °C/W
= PINT + PI/O
PINT
PI/O
= chip internal power, IDD × VDD, watts
= power dissipation on input and output pins — user determined, watts
For most applications PI/O < PINT and can be ignored. An approximate relationship between PD and TJ (if PI/O is neglected) is:
PD = K ÷ (TJ + 273°C)
(2)
Solving equations 1 and 2 for K gives:
K = PD × (TA + 273 °C) + ΘJMA × PD
2
(3)
where K is a constant pertaining to the particular part. K can be determined from equation (3) by measuring PD (at equilibrium)
for a known TA. Using this value of K, the values of PD and TJ can be obtained by solving equations (1) and (2) iteratively for
any value of TA.
2.4
Flash Memory Characteristics
The flash memory characteristics are shown in Table 11 and Table 12.
Table 11. SGFM Flash Program and Erase Characteristics
(VDDF = 2.7 to 3.6 V)
Parameter
System clock (read only)
System clock (program/erase)2
Symbol
Min
Typ
Max
Unit
fsys(R)
0
—
—
66.67 or 801
66.67 or 801
MHz
MHz
fsys(P/E)
0.15
1
Depending on packaging; see Table 12.
Refer to the flash memory section for more information
2
Table 12. SGFM Flash Module Life Characteristics
(VDDF = 2.7 to 3.6 V)
Parameter
Symbol
Value
Unit
Maximum number of guaranteed program/erase cycles1 before failure
P/E
10,0002
10
Cycles
Years
Data retention at average operating temperature of 85°C
Retention
1
A program/erase cycle is defined as switching the bits from 1 → 0 → 1.
Reprogramming of a flash memory array block prior to erase is not required.
2
MCF52259 ColdFire Microcontroller, Rev. 0
32
Freescale Semiconductor
FREESCALE [ Freescale ]
