bd95710muv-e2 ROHM Co. Ltd., bd95710muv-e2 Datasheet - Page 19

• Manufacturer Part Number: bd95710muv-e2
• Description: 2phase Switching Regulator Controllers Graphic Card
• Manufacturer: ROHM Co. Ltd.

●Power Dissipation
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BD95710MUV
www.rohm.com
Parasitic element
11. Regarding input pin of the IC
12. Ground Wiring Pattern
This monolithic IC contains P+ isolation and P substrate layers between adjacent elements in order to keep them isolated.
P-N junctions are formed at the intersection of these Payers w the N layers of other elements, creating a parasitic diode or
transistor. For example, the relation between each potential is as follows:
When GND > Pin A and GND > Pin B, the P-N junction operates as a parasitic diode.
When GND > Pin B, the P-N junction operates as a parasitic transistor.
Parasitic diodes can occur inevitable in the structure of the IC. The operation of parasitic diodes can result in mutual
interference among circuits, operational faults, or physical damage. Accordingly, methods by which parasitic diodes
operate, such as applying a voltage that is lower than the GND (P substrate) voltage to an input pin, should not be used.
When using both small signal and large current GND patterns, it is recommended to isolate the two ground patterns,
placing a single ground point at the ground potential of application so that the pattern wiring resistance and voltage
variations caused by large currents do not cause variations in the small signal ground voltage. Be careful not to change the
GND wiring pattern of any external components, either.
Pin A
3.0
2.0
1.0
4.0
N
0
P
0
①3.56W
Fig.25 Thermal derating curve
+
②1.21W
③0.70W
④0.34W
N
25
Ambient temperature:Ta [℃]
(VQFN020V4040)
50
GND
P
P substrate
75
P
① 4 layers (Copper foil area : 5505mm
② 4 layers (Copper foil area : 10.29m
③ 4 layers (Copper foil area : 10.29m
④IC only.
+
θj-a=103.3℃/W
copper foil in each layers.
θj-a=35.1℃/W
copper foil in each layers.
θj-a=178.6℃/W
θj-a=367.6℃/W
N
Resistor
100
105
Pin A
125
150
Parasitic
element
2
2
)
)
2
)
Parasitic element
Pin B
N
19/20
P
+
C
B
N
E
GND
P
P substrate
Transistor (NPN)
P
+
N
GND
Other adjacent elements
Pin B
B
C
E
Technical Note
2009.04 - Rev.B
GND
Parasitic
element