Datasheet
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TSZ02201-0RAR1G200630-1-2
TSZ22111･15･001 12/17 20.Feb.2013 Rev.001
BA4558Yxxx-M
●Power Dissipation
Power dissipation (total loss) indicates the power that the IC can consume at Ta=25°C (normal temperature). As the IC
consumes power, it heats up, causing its temperature to be higher than the ambient temperature. The allowable
temperature that the IC can accept is limited. This depends on the circuit configuration, manufacturing process, and
consumable power.
Power dissipation is determined by the allowable temperature within the IC (maximum junction temperature) and the
thermal resistance of the package used (heat dissipation capability). Maximum junction temperature is typically equal to the
maximum storage temperature. The heat generated through the consumption of power by the IC radiates from the mold
resin or lead frame of the package. Thermal resistance, represented by the symbol θja°C/W, indicates this heat dissipation
capability. Similarly, the temperature of an IC inside its package can be estimated by thermal resistance.
Figure 24. (a) shows the model of the thermal resistance of the package. The equation below shows how to compute for the
Thermal resistance (θja), given the ambient temperature (Ta), maximum junction temperature (Tjmax), and power
dissipation (Pd).
θja = (Tjmax - Ta) / Pd ℃/W ・・・・・ (Ⅰ)
The Derating curve in Figure 24. (b) indicates the power that the IC can consume with reference to ambient temperature.
Power consumption of the IC begins to attenuate at certain temperatures. This gradient is determined by Thermal
resistance (θja), which depends on the chip size, power consumption, package, ambient temperature, package condition,
wind velocity, etc. This may also vary even when the same of package is used. Thermal reduction curve indicates a
reference value measured at a specified condition. Figure 25. (c) shows an example of the derating curve for
BA4558Yxxx-M.
( 8 ) ( 9 ) (10) Unit
6.2 5.0 4.8 mW/℃
When using the unit above Ta=25℃, subtract the value above per Celsius degree .
Mounted on a FR4 glass epoxy board 70mm×70mm×1.6mm(cooper foil area below 3%)
(a) Thermal resistance
(b) Derating curve
Figure 24. Thermal resistance and derating
0 50 75 100 125 15025
P1
P2
Pd (max)
LSI
の消費電力
[W]
θ' ja2
θ' ja1
Tj ' (max)
θja2 < θja1
周囲温度
Ta [
℃
]
θ ja2
θ ja1
Tj (max)
Power dissipation of LSI
Ambient temperature
Figure 25. Derating curve
mbient temperature
Ta
Chip surface temperature
Tj
[℃]
Power dissipation Pd[W]
θja = ( Tjmax
-
Ta) / Pd
℃
/W
[℃]
(c) BA4558Yxxx-M
0
200
400
600
800
1000
0 25 50 75 100 125
AMBIENT TEMPERATURE [
℃
] .
POWER DISSIPATION [mW] .
BA4558YFVM-M(10)
BA4558YFV-M(9)
BA4558YF-M(8)
