Datasheet

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TSZ02201-0RAR0G200100-1-2

© 2012 ROHM Co., Ltd. All rights reserved.

35/39

27.FEB.2012 Rev.001

TSZ22111･15･001

BA3472, BA3472R, BA3474, BA3474R

Derating curves

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. Fig.98 (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.98 (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. Fig.99(c) ~ (f) shows a derating curve for an example of BA3472, BA3474, BA3472R,

BA3474R.

(*10)

(*11)

(*12)

(*13)

(*14)

(*15)

(*16)

(*17)

(*18)

(*19)

Unit

6.2

5.5

4.7

7.0

4.9

5.0

5.7

7.5

9.5

13.5

[mW/℃]

When using the unit above Ta=25[℃], subtract the value above per degree[℃].

(*10) (*11) (*12) (*13) (*14) Mounted on a glass epoxy 1 layers PCB 70[mm]×70[mm]×1.6[mm] (occupied copper area：below 3[%]).

(*15) Mounted on a glass epoxy 2 layers PCB 70[mm]×70[mm]×1.6[mm] (occupied copper area：15mm×15mm).

(*16) (*18) Mounted on a glass epoxy 2 layers PCB 70[mm]×70[mm]×1.6[mm] (occupied copper area：70mm×70mm).

(*17) (*19) Mounted on a glass epoxy 4 layers PCB 70[mm]×70[mm]×1.6[mm] (occupied copper area：70mm×70mm).

Fig. 99 Derating curve

Fig. 98 Thermal resistance and derating curve

(a) Thermal resistance

(b) Derating curve

周囲温度 Ta [℃]

チップ 表面温度 Tj [℃]

消費電力 P [W]

θja = ( Tj ーTa ) / Pd [℃/W]

Ambient temperature

Chip surface temperature

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)

Ambient temperature

Power dissipation of LSI

Power dissipation Pd [W]

0

200

400

600

800

1000

0

25

50

75

100

125

周囲温度 [℃]

0

200

400

600

800

1000

1200

1400

1600

1800

0

25

50

75

100

125

周囲温度 Ta [℃]

(e)BA3472R

(f)BA3474R

BA3472RFVM

590mW(*12)

BA3474RFV

105

105

870mW(*13)

625mW(*15)

713mW(*16)

937mW(*17)

1187mW(*18)

1689mW(*19)

0

200

400

600

800

1000

0

25

50

75

100

125

周囲温度 Ta [℃]

0

200

400

600

800

1000

0

25

50

75

100

125

周囲温度 Ta [℃]

(c)BA3472

870mW(*13)

590mW(*12)

BA3472FVM

BA3472F

BA3472FV

(d)BA3474

780mW(*10)

690mW(*11)

610mW(*14)

BA3474F

BA3474FV

85

85

Ambient Temperature: Ta [℃]

Ambient Temperature: Ta [℃]

Ambient Temperature: Ta [℃]

Ambient Temperature: Ta [℃]