Datasheet
www.rohm.com TSZ02201-0RAR1G200060-1-2
© 2012 ROHM Co., Ltd. All rights reserved.
14/18
9.NOV.2012 Rev.001
TSZ22111･15･00
BA14741xx
(b) Derating curve
●Power Dissipation
Power dissipation(total loss) indicates the power that can be consumed by IC at Ta=25℃(normal temperature). IC is heated
when it consumed power, and the temperature of IC chip becomes higher than ambient temperature. The temperature that
can be accepted by IC chip depends on circuit configuration, manufacturing process, and consumable power is limited.
Power dissipation is determined by the temperature allowed in IC chip(maximum junction temperature) and thermal
resistance of package(heat dissipation capability). The maximum junction temperature is typically equal to the maximum
value in the storage temperature range. Heat generated by consumed power of IC radiates from the mold resin or lead
frame of the package. The parameter which indicates
this heat dissipation capability(hardness of heat release)is called
thermal resistance, represented by the symbol θja
℃/W. The temperature of IC inside the package can be estimated by this
thermal resistance. Figure 28. (a) shows the model of thermal resistance of the package. Thermal resistance θja, ambient
temperature Ta, maximum junction temperature Tjmax, and power dissipation Pd can be calculated by the equation below:
θja = (Tjmax-Ta) / Pd ℃/W ・・・・・ (Ⅰ)
Derating curve in Figure 28. (b) indicates power that can be consumed by IC with reference to ambient temperature. Power
that can be consumed by IC with reference to ambient temperature. Power that can be consumed by IC begins to attenuate
at certain ambient temperature. This gradient is determined by thermal resistance θja. Thermal resistance θja depends on
chip size, power consumption, package, ambient temperature, package condition, wind velocity, etc even when the same of
package is used. Thermal reduction curve indicates a reference value measured at a specified condition. Figure 29. (c)
show a derating curve for an example of BA 14741.
(*8) (*9) Unit
8.2 4.5
mW/
℃
When using the unit above Ta=25℃, subtract the value above per degree℃. Permissible dissipation is the value.
Permissible dissipation is the value when FR4 glass epoxy board 70mm ×70mm ×1.6mm (cooper foil area below 3%) is mounted.
周囲温度
Ta [
℃
]
チップ表面温度
Tj [
℃
]
消費電力 P [W]
Figure 29. Derating curve
(a) Thermal resistance
Figure 28. Thermal resistance and derating
curve
(c)BA14741
490mW (*9)
0
200
400
600
800
1000
0 25 50 75 100 125
POWER DISSIPATION [mW]
AMBIENT TEMPERATURE [℃]
BA14741FJ
820mW (*8)
BA14741F
Ambient temperature Ta [℃]
Chip surface temperature Tj [℃]
Power dissipation Pd [W]
θja=(Tjmax-Ta)/Pd ℃/W
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 [W]
mbient temperature Ta [℃]
