BU7261G Datasheet, PDF (28/33 Pages) Rohm – Low Voltage Operation CMOS Operational Amplifiers

BU7261G,BU7261SG,BU7241G,BU7241SG,BU7262F/FVM,BU7262SF/FVM,BU7242F/FVM,BU7242SF/FVM
BU7461G,BU7461SG,BU7441G,BU7441SG,BU7462F/FVM,BU7462SF/FVM,BU7442F/FVM,BU7442SF/FVM
Technical Note
2.11 Slew rate (SR)
Indicates the time fluctuation ratio of voltage output when step input signal is applied.
2.12 Unity gain frequency (ft)
Indicates a frequency where the voltage gain of Op-Amp is 1.
2.13 Total harmonic distortion + Noise (THD+N)
Indicates the fluctuation of input offset voltage or that of output voltage with reference to the change of output voltage of
driven channel.
2.14 Input referred noise voltage (Vn)
Indicates a noise voltage generated inside the operational amplifier equivalent by ideal voltage source connected in series
with input terminal.
●Derating curve
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.190 (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 :
θja ＝ (Tj-Ta) / Pd [℃/W]
・・・・・ (Ⅰ)
Derating curve in Fig.190(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 iis 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. Fig191(c)-(f) show a derating curve
for an example of BU7261/41family,BU7262/42family.,7461/7441family,7462/7442family.
Power dissipation of LS[IW[W] ]
Pd(max)
θja _＝ (Tj_－Ta) / Pd [_℃/W]
P2
Ambient tem^周p^囲e^温ra^度tur^Te^aT^[℃a ^][℃]
パPッaケcーkaジg表e面su温rf度acTeat[℃em] perature [℃]
P1
θja1
θja2 <θja1
θja2
Tj(max)
Chip surface tチemッpプe表ra面tu温re度Tj^T[℃^j[℃]^]
Power dissipation P消[費W電] 力P[W]
(a) Thermal resistance
0
25
50
Ambient temperature Ta [℃]
75
100
125
BU7462/BU7442
Tj(max)
(b) Derating curve
Fig. 190 Thermal resistance and derating
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2009.05 - Rev.A