Datasheet

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TSZ02201-0RAR1G200110-1-2

TSZ22111･15･001

20/27

21.Jan.2013 Rev.002

BA2904Yxxx-C, BA2902Yxx-C

●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 50. (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), junction temperature (Tj), and power dissipation (Pd).

θja = (Tjmax - Ta) / Pd

℃/W

・・・・・

(Ⅰ)

The Derating curve in Figure 50. (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 51. (c),(d) shows an example of the derating curve for

BA2904Yxxx-C, BA2902Yxx-C.

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%)

(12)

(13)

(14)

(15)

(16)

Unit

6.2

5.0

4.8

7.0

4.5

mW/℃

(a) Thermal resistance

(b) Derating curve

Figure 50. Thermal resistance and derating

0

50

75

100

125

150

25

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 51. Derating curve

Ambient temperature

Ta ℃

Power dissipation

Pd[W]

θja = ( Tjmax - Ta) / Pd

℃ /W

(c) BA2904Yxxx-C

(d) BA2902Yxx-C

0

200

400

600

800

1000

0

25

50

75

100

125

150

AMBIENT TEMPERATURE [℃]

BA2904YFVM-C(14)

BA2904YFV-C(13)

BA2904YF-C(12)

0

200

400

600

800

1000

0

25

50

75

100

125

150

AMBIENT TEMPERATURE [℃]

BA2902YFV-C(15)

BA2902YF-C(16)