str912fa STMicroelectronics, str912fa Datasheet - Page 74

• Manufacturer Part Number: str912fa
• Description: Arm966e-s? 16/32-bit Flash Mcu With Ethernet, Usb, Can, Ac Motor Control, 4 Timers, Adc, Rtc, Dma
• Manufacturer: STMicroelectronics

Package mechanical data
7.1
74/78
Thermal characteristics
The average chip-junction temperature, T
The average chip-junction temperature, T
following equation:
Where:
P
Most of the time for the applications P
P
memories. The worst case P
An approximate relationship between P
Therefore (solving equations 1 and 2):
where:
Table 34.
I/O
I/O
Symbol
represents the Power Dissipation on Input and Output Pins;
may be significant if the device is configured to drive continuously external modules and/or
T
–
–
–
–
P
K = P
–
J
Θ
Θ
Θ
D
= T
JA
JA
JA
= K / (T
T
Θ
P
P
Power.
K is a constant for the particular part, which may be determined from equation (3) by
measuring P
and T
D
A
A
D
INT
JA
Thermal characteristics
x (T
+ (P
is the Ambient Temperature in °C,
is the sum of P
is the Package Junction-to-Ambient Thermal Resistance, in ° C/W,
is the product of I
J
J
A
Thermal Resistance Junction-Ambient
LQFP 80 - 12 x 12 mm / 0.5 mm pitch
Thermal Resistance Junction-Ambient
LQFP128 - 14 x 14 mm / 0.4 mm pitch
Thermal Resistance Junction-Ambient
LFBGA 144 - 10 x 10 x 1.7mm
may be obtained by solving equations (1) and (2) iteratively for any value of T
D
+ 273°C) (2)
+ 273°C) + Θ
x Θ
JA
D
)(1)
(at equilibrium) for a known T
INT
INT
JA
and P
DD
of the STR91xFA is 500mW (I
x P
and V
Parameter
D
I/O
I/O
2
D
(3)
(P
< P
DD
and T
J
J
, in degrees Celsius, may be calculated using the
D
must never exceed 125° C.
, expressed in Watts. This is the Chip Internal
INT
= P
J
and may be neglected. On the other hand,
INT
(if P
+ P
I/O
A.
I/O
is neglected) is given by:
Using this value of K, the values of P
),
DD
x V
DD
, or 250mA x 2.0V).
Value
41.5
36.5
38
STR91xFA
°C/W
°C/W
°C/W
Unit
D
A
.