bd9842fv ROHM Co. Ltd., bd9842fv Datasheet - Page 14

• Manufacturer Part Number: bd9842fv
• Description: Dual-output High Voltage High-frequency Step-down Switching Regulator Controller Type
• Manufacturer: ROHM Co. Ltd.

● Precaution for use
1)
2)
3)
4)
5)
6)
7)
Use in intense magnetic field may result in malfunction. Be careful.
In inspection on set board, when a capacitor is connected to a terminal with low impedance, stress may be applied to IC,
therefore be sure to discharge electricity in each process. Apply grounding to assembling process for a measure against
static electricity, and take enough care in transport and storage. When connecting a jig in inspection process, be sure to
turn off power before detaching IC.
About maximum absolute rating
GND potential
Thermal design
Shorting between terminals and wrong attachment
Operation in intense magnetic field
Inspection on set board
About IC terminal input
When the maximum absolute rating of application voltage or operation voltage range is exceeded, it may lead to
deterioration or rupture. It is impossible to forecast rupture in short mode or open mode. When a special mode is
expected exceeding the maximum absolute rating, try to take a physical safety measure such as a fuse.
Ensure that the potential of GND terminal is the minimum in any operation condition. Also ensure that no terminal except
GND terminal has a voltage below GND voltage including actual transient phenomenon.
Allow a sufficient margin in thermal design in consideration of permissible loss (Pd) in actual use condition.
When attaching an IC to a set board, pay full attention to the direction of IC and dislocation. Wrong attachment may
cause rupture of IC. In addition, when shorting is caused by foreign substance placed between outputs or between output
and power supply-GND, rupture is also possible.
This IC is a monolithic IC, and contains P
P-layer and N-layer of each element form P-N junction, and many kinds of parasitic elements are constituted. (See Fig
43.)
For example, when resistor and transistor are connected with a terminal as shown below.
Parasitic element is inevitably generated by potential because of IC structure. Operation of parasitic element causes
interference with circuit operation, and may lead to malfunction, and also may cause rupture. Therefore when applying a
voltage lower than GND (P board) to I/O terminal, pay full attention to usage so that parasitic elements do not operate.
○ P-N junction operates as a parasitic diode when GND>(Terminal A) for resistor, and when GND>(Terminal B) for
○ In addition, when GND>(Terminal B) for transistor (NPN), parasitic NPN transistor is operated by N-layer of some other
transistor (NPN).
elements in the vicinity of parasitic diode mentioned above.
(Terminal A)
（ 端子Ａ ）
(Terminal A)
Ｎ
（ 端子A)
P
＋
P board
Ｐ 基板
Resistor
GND
抵抗
GND
Ｎ
寄生素子
Parasitic element
Ｐ
Parasitic element
寄生素子
+
isolation and P board for separating elements between each element. This
P
＋
Fig.44
Ｎ
14/15
Another element
in the vicinity
近接する 他の素子
（ 端子B）
(Terminal B)
(Terminal B)
Ｎ
Parasitic element
（ 端子Ｂ ）
P
＋
寄生素子
C
Transistor (NPN)
ト ラ ン ジスタ （ NPN)
P board
B
Ｐ 基板
GND
Ｎ
Ｎ
E
Ｂ
Ｐ
Ｅ
GND
Ｃ
Ｐ ＋
Parasitic element
寄生素子
Ｎ
GND