BU7205HFV ROHM [Rohm], BU7205HFV Datasheet - Page 26

• Manufacturer Part Number: BU7205HFV
• Description: Ultra Low Power CMOS Operational Amplifiers
• Manufacturer: ROHM [Rohm]

●Derating Curve
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BU7265G,BU7265SG,BU7205HFV,BU7205SHFV,BU7271G,BU7271SG,BU7245HFV,BU7245SHFV,
BU7411G,BU7411SG,BU7421G,BU7421SG,BU7475HFV,BU7475SHFV
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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 ship 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
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 θj-a[℃/W]. The temperature of IC inside the package can be estimated by this thermal resistance.
Fig.172 (a) shows the model of thermal resistance of the package. Thermal resistance θja, ambient temperature Ta, junction
temperature Tj, and power dissipation Pd can be calculated by the equation below:
Derating curve in Fig.172 (b) indicates 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. Fig.173(c)-(d) show a derating curve for an example of BU7265 / BU7205 / BU7271 /
BU7245 / BU7411 / BU7421 / BU7475 family.
When using the unit above Ta=25[℃], subtract the value above per degree[℃]. Permissible dissipation is the value
when FR4 glass epoxy board 70[mm]×70[mm]×1.6[mm] (cooper foil area below 3[％]) is mounted
(a) Thermal resistance
θja = (Tj ‐ Ta) / Pd [ ℃ / W]
Chip surface temperature Tj
(e) BU7265SG BU7271SG BU7411SG BU7421SG
Ambient temperature Ta ℃ ]
1000
1000
(c) BU7265G BU7271G BU7411G BU7421G
800
600
400
200
800
600
400
200
0
0
0
0
θja = (Tj－Ta) / Pd
(*23)
5.4
AMBIENT TEMPERATURE[ ℃ ]
AMBIENT TEMPERATURE[ ℃ ]
Package face temperature
50
Fig.172 Thermal resistance and derating
50
540[mW]
540[mW]
℃
85
]
100
100
BU7265G(*23)
BU7271G(*23)
BU7411G(*23)
BU7421G(*23)
BU7265SG(*23)
BU7271SG(*23)
BU7411SG(*23)
BU7421SG(*23)
105
Pd[W]
Fig.173 Derating Curve
[℃/W]
Ta[ ℃ ]
150
150
26/28
(*24)
5.35
P2
P1
・・・・・ (Ⅰ)
0
1000
(f) BU7205SHFV BU7245SHFV BU7475SHFV
1000
800
600
400
200
(d) BU7205HFV BU7245HFV BU7475HFV
800
600
400
200
Pd(max)
0
0
25
Ambient temperature Ta[℃]
0
[W]
0
(b) Derating curve
AMBIENT TEMPERATURE[ ℃ ]
50
AMBIENT TEMPERATURE[ ℃ ]
θja1
50
50
75
535[mW]
535[mW]
[mW/℃]
85
θja2 <θja1
Unit
100
100
θja2
100
BU7205HFV(*24)
BU7245HFV(*24)
BU7475HFV(*24)
BU7205SHFV(*24)
BU7245SHFV(*24)
BU7475SHFV(*24)
105
125
Tj(max)
150
150
Technical Note
2010.12 - Rev.A