MC9S08DZ128 Datasheet, PDF (421/458 Pages) Freescale Semiconductor, Inc – Microcontrollers

Appendix A Electrical Characteristics
Table A-3. Thermal Characteristics
Num
C
Rating
Symbol
Value
Unit
D Operating temperature range (packaged)
1
P¹
T_A
V
T_L to T_H
–40 to 85
–40 to 105
°C
M
–40 to 125
2
T Maximum junction temperature
Thermal resistance ^2,3
Single-layer board
T_J
135
D
100-pin LQFP
61
3
64-pin LQFP
θ_JA
48-pin LQFP
Thermal resistance^2,3
Four-layer board
67
°C/W
75
4
D
100-pin LQFP
64-pin LQFP
θ_JA
48-pin LQFP
48
49
°C/W
52
1 _{Freescale may eliminate a test insertion at a particular temperature from the production test flow once sufficient}
data has been collected and is approved.
2 _{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.
3 _{Junction to Ambient Natural Convection}
The average chip-junction temperature (T_J) in °C can be obtained from:
T_J = T_A + (P_D × θ_JA)
Eqn. A-1
where:
T_A = Ambient temperature, °C
θ_JA = Package thermal resistance, junction-to-ambient, °C/W
P_D = P_int + P_I/O
P_int = I_DD × V_DD, Watts — chip internal power
P_I/O = Power dissipation on input and output pins — user determined
For most applications, P_I/O << P_int and can be neglected. An approximate relationship between P_D and T_J
(if P_I/O is neglected) is:
P_D = K ÷ (T_J + 273°C)
Solving equations 1 and 2 for K gives:
Eqn. A-2
K = P_D × (T_A + 273°C) + θ_JA × (P_D)²
Eqn. A-3
MC9S08DZ128 Series Data Sheet, Rev. 1
Freescale Semiconductor
421