BU7441G Datasheet, PDF (30/44 Pages) Rohm – Ground Sense Low Voltage Operation CMOS Operational Amplifiers

BU7441G BU7441SG BU7442xxx BU7442Sxxx BU7444F BU7444SF Datasheet
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 78 (a) shows the model of the thermal resistance of a 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 °C/W
The Derating curve in Figure 78 (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 78(c) to (h) shows an example of the derating curve for BU7441G, BU7441SG,
BU7442xxx, BU7442Sxxx, BU7444F and BU7444SF.
θJA=(TJmax-TA)/ PD °C/W
Ambient temperature TA [ °C ]
Chip surface temperature TJ [ °C ]
(a) Thermal Resistance
Power dissipation of LSI [W]
PDmax
P2
θJA2 < θJA1
P1
θJA2
θJA1
TJmax
0
25
50
75
100
125
Ambient temperature TA[C]
(b) Derating Curve
1.0
0.8
0.6
BU7441G(Note 26)
0.4
0.2
0.0
0
85
25 50 75 100 125 150
Ambient Temperature [°C]
(c) BU7441G
1.0
0.8
0.6
0.4
BU7441SG(Note 26)
0.2
0.0
0
105
25 50 75 100 125 150
Ambient Temperature [°C]
(d) BU7441SG
Figure 78. Thermal Resistance and Derating Curve
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13.Feb.2015 Rev.002