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Datasheet

Datasheet

BD6971FS

TSZ02201-0H1H0B100160-1-2

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

28.JUL.2012 Rev.002

www.rohm.com

TSZ22111・15・001

●Power dissipation

Power dissipation (total loss) indicates the power that can be consumed by IC at Ta=25°C (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[°C/W]. This heat resistance can estimate the temperature of IC inside the package. Fig.25 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 de-rating 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 de-rating curve indicates a reference value

measured at a specified condition. Fig.26 shows a thermal de-rating curve (Value when mounting FR4 glass epoxy board

70[mm] x 70[mm] x 1.6[mm] (copper foil area below 3[%])). Thermal resistance

θjc from IC chip joint part to the package

surface part of mounting the above-mentioned same substrate is shown in the following as a reference value.

＊Reduce by 6.5mW/°C over 25°C

(On 70.0mm x 70.0mm x 1.6mm glass epoxy board)

●I/O equivalence circuit(Resistance values are typical)

1) Power supply terminal,

2) Hall input terminals,

3) Minimum output duty setting

4) Motor output terminals,

and Ground terminal

Output duty controllable input

terminal

and Output current

terminal,

detecting resistor

and Output current detection

connecting terminal

terminal

5) Reference voltage output

6) Speed pulse signal output

7) Oscillating capacitor connecting

terminal,

terminal

terminal

and Hall bias terminal

OSC

Vcc

1k

Ω

Vcc

1k

Ω

500

750

Pd[mW]

0

25

50

75

100

125

150

Ta[°C]

250

812.5

θja=153.8 [°C/W]

θja = (Tj – Ta) / P [°C/W]

θjc = (Tj – Tc) / P [°C/W]

Fig.25 Thermal resistance

Fig.26 Thermal de-rating curve

θja = (Tj – Ta) / P [°C/W]

θjc = 43 [°C/W] (reference value)

Chip surface temperature Tj[°C]

Package surface temperature Tc[°C]

Power consumption P[W]

Ambient temperature Ta[°C]

TH

1k

Ω

H+

H–

CS

Vcc

10

Ω

FG

Vcc

OUT1

OUT2

RNF

Vcc

GND

REF

46k

Ω

Vcc

HB

46k

Ω

Vcc

MIN

1k

Ω

Vcc

30

Ω