bd9575fv-e2 ROHM Co. Ltd., bd9575fv-e2 Datasheet - Page 19

• Manufacturer Part Number: bd9575fv-e2
• Description: Switching Regulators Ddr-sdram Cores
• Manufacturer: ROHM Co. Ltd.

●Thermal Derating Curve
© 2009 ROHM Co., Ltd. All rights reserved.
BD9575FV
www.rohm.com
11. Regarding input pin of the IC
12. Ground Wiring Pattern
◎SSOP-B20
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 P layers with the N layers of other elements, creating a parasitic diode
or transistor. For example, the relation between each potential is as follows:
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.
Parasitic element
[mW]
0.5
1
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.
Pin A
0
N
0
②
①
P
+
N
25
Ambient Temperature [Ta]
GND
50
P
P substrate
P
+
75
N
Resistor
Example of IC structure
100
Pin A
125
Parasitic
element
150
[℃]
Parasitic element
19/20
①IC only
②1 layer board
Pin B
N
θja=250℃/W
(70mm×70mm×1.6mm70.0mm×70mm×1.6mm Glass-epoxy PCB).
θja=153.8℃/W
P
+
C
B
N
E
GND
P
P substrate
Transistor (NPN)
P
+
N
GND
Other adjacent elements
Pin B
B
Technical Note
2009.04 - Rev.B
C
E
GND
Parasitic
element