at91rm3400 ATMEL Corporation, at91rm3400 Datasheet - Page 445

• Manufacturer Part Number: at91rm3400
• Description: Atmel Advanced At91 Arm Microcontroller
• Manufacturer: ATMEL Corporation

Mechanical Characteristics
Thermal Data
Junction Temperature
1790A–ATARM–11/03
In Table 87, the device lifetime is estimated using the MIL-217 standard in the “moderately
controlled” environmental model (this model is described as corresponding to an installation in
a permanent rack with adequate cooling air), depending on the device Junction Temperature.
(For details see the section “Junction Temperature” on page 445.)
Note that the user must be extremely cautious with this MTBF calculation. It should be noted
that the MIL-217 model is pessimistic with respect to observed values due to the way the
data/models are obtained (test under severe conditions). The life test results that have been
measured are always better than the predicted ones.
Table 87. MTBF Versus Junction Temperature
Table 88 summarizes the thermal resistance data depending on the package.
Table 88. Thermal Resistance Data
The average chip-junction temperature, T
•
•
where:
•
•
•
•
•
From the first equation, the user can derive the estimated lifetime of the chip and decide if a
cooling device is necessary or not. If a cooling device is to be fitted on the chip, the second
equation should be used to compute the resulting average chip-junction temperature T
Symbol
JA
JC
page 445
Table 88 on page 445
P
Consumption” on page 434
T
T
T
JA
JC
HEAT SINK
A
J
J
D
Junction Temperature (T
= ambient temperature (°C)
=
= device power consumption (W) estimated from data provided in the section “Power
= package thermal resistance, Junction-to-ambient (°C/W), provided in Table 88 on
=
= package thermal resistance, Junction-to-case thermal resistance (°C/W), provided in
T
T
A
A
+
Parameter
Junction-to-ambient thermal resistance
Junction-to-case thermal resistance
+
= cooling device thermal resistance (°C/W), provided in the device datasheet
P
P
D
D
100
125
150
175
HEATSINK
JA
J
) (°C)
+
JC
J
, in °C can be obtained from the following:
Estimated Lifetime (MTBF) (Year)
Condition
Still Air
9
5
2
1
LQFP100
LQFP100
Package
AT91RM3400
40.2
13.1
Typ
J
°C/W
in °C.
Unit
445