MC9S08MP16 Datasheet, PDF (10/36 Pages) Freescale Semiconductor, Inc – 8-Bit HCS08 Central Processor Unit (CPU)

Electrical Characteristics
2.4 Thermal Characteristics
This section provides information about operating temperature range, power dissipation, and package thermal resistance. Power
dissipation on I/O pins is usually small compared to the power dissipation in on-chip logic and voltage regulator circuits, and
it is user-determined rather than being controlled by the MCU design. To take P_I/O into account in power calculations, determine
the difference between actual pin voltage and V_SS or V_DD and multiply by the pin current for each I/O pin. Except in cases of
unusually high pin current (heavy loads), the difference between pin voltage and V_SS or V_DD will be very small.
Table 4. Thermal Characteristics
Num C
Rating
Symbol
Consumer &
Industrial
Automotive
Unit
1 — Operating temperature range (packaged)
T_A
2
D Maximum junction temperature
T_J
3
D Thermal resistance ^1,2
single-layer board
48-pin LQFP
32-pin LQFP
θ_JA
28-pin SOIC
4
D Thermal resistance ^1,2
four-layer board
–40 to 105
115
80
85
71
–40 to 125
°C
135
°C
80
—
°C/W
—
48-pin LQFP
56
56
32-pin LQFP
28-pin SOIC
θ_JA
57
48
—
°C/W
—
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 _{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. 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 Equation 1 and Equation 2 for K gives:
Eqn. 2
K = P_D × (T_A + 273°C) + θ_JA × (P_D)²
Eqn. 3
MC9S08MP16 Series Data Sheet, Rev. 1
10
Freescale Semiconductor