bh6799fvm ROHM Co. Ltd., bh6799fvm Datasheet - Page 14
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bh6799fvm
Manufacturer Part Number
bh6799fvm
Description
Dc Brushless Motor Driver Series For Cooling Fans Low-voltage Single-phase Full-wave Dc Brushless Fan Motor Drivers
Manufacturer
ROHM Co. Ltd.
Datasheet
1.BH6799FVM.pdf
(17 pages)
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Manufacturer
Quantity
Price
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Manufacturer:
Fastron
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Part Number:
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Manufacturer:
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● Thermal derating curve
Power dissipation (total loss) indicates the power that can be consumed by IC at Ta = 25ºC (normal temperature). IC is
heated when it consumes 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, etc, 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 in
general equal to the maximum value in the storage temperature range.
Heat generated by consumed power of IC is radiated from the mold resin or lead frame of package. The parameter
which indicates this heat dissipation capability (hardness of heat release) is called heat resistance, represented by the
symbol θja [ ℃ /W]. The temperature of IC inside the package can be estimated by this heat resistance. Fig.37 shows the
model of heat resistance of the package.
Heat resistance θja, ambient temperature Ta, junction temperature Tj, and power consumption P can be calculated by
the equation below:
Thermal derating curve 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, packaging condition,
wind velocity, etc., even when the same package is used. Thermal derating curve indicates a reference value measured
at a specified condition. Fig.38 shows a thermal derating curve (Value when mounting FR4 glass epoxy board 70 [mm] x
70 [mm] x 1.6 [mm] (copper foil area below 3 [%]))
Pd(mW)
700
600
585
500
400
300
200
100
* Reduce by 4.68 mW/°C over 25°C.
0
(70.0mm × 70.0mm × 1.6mm glass epoxy board)
25
θ ja = (Tj - Ta) / P
Fig.38 Thermal derating curve
θ ja = (Tj-Ta) / P
Fig.37 Thermal resistance
50
Power consumption P[W]
Chip surface temperature Tj[℃]
14/16
Ambient temperature Ta[℃]
75
100
[ ℃ /W]
105
[ ℃ /W]
125
150
BD6989FVM 、 BH6799FVM
BH6789FVM 、 BH6766FVM
Ta( ℃ )