Technical Note

5/8

BD63940EFV, BD63960EFV

www.rohm.com

2012.02 - Rev.A

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

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Power dissipation

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HTSSOP-B24 Package (BD63940EFV/BD63960EFV))

HTSSOP-B24 has exposed metal on the back, and it is possible to dissipate heat from a through hole in the back. Also, the

back of board as well as the surfaces has large areas of copper foil heat dissipation patterns, greatly increasing power

dissipation. The back metal is shorted with the back side of the IC chip, being a GND potential, therefore there is a

possibility for malfunction if it is shorted with any potential other than GND, which should be avoided. Also, it is

recommended that the back metal is soldered onto the GND to short. Please note that it has been assumed that this

product will be used in the condition of this back metal performed heat dissipation treatment for increasing heat dissipation

efficiency.

Ambient Temperature : Ta[℃]

3.0

2.0

1.0

100

125

4.0W

0

4

4.0

Measurement machine：TH156（Kuwano Electric）

Measurement condition：ROHM board

Board size：70*70*1.6mm

3

(With through holes on the board)

The exposed metal of the backside is connected to the board with

solder.

Board①：1-layer board(Copper foil on the back 0mm

Board②：2-layer board(Copper foil on the back 15*15mm

Board③：2-layer board(Copper foil on the back 70*70mm

Board④：4-layer board(Copper foil on the back 70*70mm

Fig.2 HTSSOP-B24 Derating curve

2.8W

1.7W

1.1W

3

2

1