BD9763FVM Datasheet, PDF (10/12 Pages) Rohm – Single-output Step-up,High-efficiency Switching Regulator (Controller Type)

BD9763FVM
Technical Note
(11) IC pin input
This monolithic IC contains P + isolation and PCB 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 to create a variety of
parasitic elements.
For example, when a resistor and transistor are connected to pins as shown in Fig.14,
○the P/N junction functions as a parasitic diode when GND > (Pin A) for the resistor or GND > (Pin B) for
the transistor (NPN).
○Similarly, when GND > (Pin B) for the transistor (NPN), the parasitic diode described above combines
With the N layer of other adjacent elements to operate as a parasitic NPN transistor.
The formation of parasitic elements as a result of the relationships of the potentials of different pins is an inevitable result
of the IC’s architecture. The operation of parasitic elements can cause interference with circuit operation as well as IC
malfunction and damage. For these reasons, it is necessary to use caution so that the IC is not used in away that will
trigger the operation of parasitic elements, such as by the application of voltage lower than the GND (PCB) voltage to input
and output pins.
(Pin A)
Ｐ^＋
ï¼®
ï¼°
ï¼®
PCB
Ｐ^＋
ï¼®
GND
Parasitic diode
(Pin B)
ï¼¢
ï¼¥
ï¼£
(Pin A)
Parasitic diode
Ｐ^＋
ï¼®
ï¼°
Ｐ^＋
ï¼®
ï¼®
PCB
GND
Parasitic transistors
Fig.14
GND
ï¼®
GND
(Pin B)
ï¼¢
Other adjacent element
ï¼£
ï¼¥
GND
Parasitic elements
●Power Dissipation Reduction
pd(W)
0.8
0.6
0.4
0.587W
0.2
0
0
25
50
75 100 125 150 175
AMBIENT TEMPERATURE ： Ta(℃）
IC mounted on a ROHM standard board (70mm x 70mm x 1.6mm, glass epoxy)
Fig.15
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© 2009 ROHM Co., Ltd. All rights reserved.
10/11
2009.05 - Rev.A