BD8961NV ROHM Co. Ltd., BD8961NV Datasheet - Page 8

• Manufacturer Part Number: BD8961NV
• Description: Low Noise Step-down Switching Regulator
• Manufacturer: ROHM Co. Ltd.

●Consideration on permissible dissipation and heat generation
As this IC functions with high efficiency without significant heat generation in most applications, no special consideration is
needed on permissible dissipation or heat generation. In case of extreme conditions, however, including lower input voltage,
higher output voltage, heavier load, and/or higher temperature, the permissible dissipation and/or heat generation must be
carefully considered.
For dissipation, only conduction losses due to DC resistance of inductor and ON resistance of FET are considered. Because
the conduction losses are considered to play the leading role among other dissipation mentioned above including gate
charge/discharge dissipation and switching dissipation.
As R
consideration on the dissipation as above, thermal design must be carried out with sufficient margin allowed.
1.0
3.0
2.0
4.0
0
ONP
Fig.25 Thermal derating curve
①3.9W
0
②0.90W
③0.64W
is greater than R
25
If V
Ambient temperature:Ta [℃]
(SON008V5060)
CC
I
50
OUT
=5V, V
=2A, for example,
R
P=2
75
ON
D=V
OUT
=0.132+0.0544
=0.1864[Ω]
2
=0.66×0.20+(1-0.66)×0.16
①for SON008V5060
②for SON008V5060
③ IC only
×0.1864＝0.7456W]
100
θj-a=32.1℃/W
θj-a=138.9℃/W
θj-a=195.3℃/W
=3.3V, R
OUT
JEDEC 4 layer board 76.2×114.3×1.6mm
ROHM standard 1 layer board 70×70×1.6mm
ONN
105
/V
125
CC
in this IC, the dissipation increases as the ON duty becomes greater.
ONP
=3.3/5.0=0.66
150
=0.2Ω, R
ONN
=0.16Ω
8/15
P=I
R
D：ON duty (=V
R
R
R
I
OUT
ON
COIL
ONP
ONN
OUT
=D×R
：Output current
：ON resistance of P-channel MOS FET
：ON resistance of N-channel MOS FET
：DC resistance of coil
2
×R
ONP
ON
+(1-D)R
OUT
/V
CC
ONN
)
With the