Datasheet

Appendix A Electrical Characteristics
MC9S08DZ128 Series Data Sheet, Rev. 1
Freescale Semiconductor 421
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) Eqn. A-2
Solving equations 1 and 2 for K gives:
K = P
D
× (T
A
+ 273°C) + θ
JA
× (P
D
)
2
Eqn. A-3
Table A-3. Thermal Characteristics
Num C Rating Symbol Value Unit
1
D Operating temperature range (packaged) T
L
to T
H
°C
P
1
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.
T
A
–40 to 85
V –40 to 105
M –40 to 125
2 T Maximum junction temperature T
J
135
Thermal resistance
2,3
Single-layer board
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
3
D 100-pin LQFP
θ
JA
61
°C/W64-pin LQFP 67
48-pin LQFP 75
4
Thermal resistance
2,3
Four-layer board
100-pin LQFP 48
°C/WD 64-pin LQFP θ
JA
49
48-pin LQFP 52