MC9S08MM128 Datasheet, PDF (15/50 Pages) Freescale Semiconductor, Inc – Advanced Information

Preliminary Electrical Characteristics
2.3 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 it is user-determined rather than
being controlled by the MCU design. In order 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 6. Thermal Characteristics
#
Symbol
Rating
Value
Unit
1
T_A
Operating temperature range (packaged):
MC9S08MM128
°C
–40 to 105
MC9S08MM64
–40 to 105
MC9S08MM32
–40 to 105
MC9S08MM32A
–40 to 105
2
T_JMAX
Maximum junction temperature
135
°C
3
θ_JA
Thermal resistance^1,2,3,4 Single-layer board — 1s
°C/W
81-pin MBGA
77
80-pin LQFP
55
64-pin LQFP
68
4
θ_JA
Thermal resistance^{1, 2, 3, 4} Four-layer board — 2s2p
°C/W
81-pin MBGA
47
80-pin LQFP
40
64-pin LQFP
49
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}
3 _{1s — Single layer board, one signal layer}
4 _{2s2p — Four layer board, 2 signal and 2 power layers}
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:
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Preliminary — Subject to Change