bd9745ekn ROHM Co. Ltd., bd9745ekn Datasheet - Page 21

• Manufacturer Part Number: bd9745ekn
• Description: 7-channel Switching Regulator Controller For Digital Camera
• Manufacturer: ROHM Co. Ltd.

○Operation Notes
１.) Absolute maximum ratings
２.) GND potential
３.) Setting of heat
４.) Pin short and mistake fitting
５.) Actions in strong magnetic field
Exposing the IC within a strong magnetic field area may cause malfunction.
６.) Mutual impedance
Use short and wide wiring tracks for the main supply and ground to keep the mutual impedance as small as possible. Use inductor and
capacitor network to keep the ripple voltage minimum.
７.) Voltage of STB pin
The threshold voltages of STB pin are 0.3V and 1.5V. STB state is set below 0.3V while action state is set beyond 1.5V.
The region between 0.3V and 1.5V is not recommended and may cause improper operation.
The rise and fall time must be under 10msec. In case to put capacitor to STB pin, it is recommended to use under 0.01μF.
８.) Thermal shutdown circuit (TSD circuit)
９.)IC Terminal Input
（Terminal A）
○ When GND > (terminal A) at the resistor and GND > (terminal B) at the transistor (NPN), the P-N junction operates as
N
○When GND > (terminal B) at the transistor (NPN), a parasitic NPN transistor operates as a result of the NHayers of other
to shut the IC off to prevent runaway thermal operation. It is not designed to protect the IC or guarantee its operation. Do not continue
to use the IC after operating this circuit or use the IC in an environment where the operation of this circuit is assumed.
This product is produced with strict quality control. However, the IC may be destroyed if operated beyond its absolute
maximum ratings. If the device is destroyed by exceeding the recommended maximum ratings, the failure mode will be difficult
to determine. (E.g. short mode, open mode) Therefore, physical protection counter-measures (like fuse) should be implemented
when operating conditions beyond the absolute maximum ratings anticipated.
Make sure GND is connected at lowest potential. All pins except NON5, must not have voltage below GND. Also, NON5 pin must
not have voltage below - 0.3V on start up.
Make sure that power dissipation does not exceed maximum ratings.
Avoid placing the IC near hot part of the PCB. This may cause damage to IC. Also make sure that the output-to-output and output
to GND condition will not happen because this may damage the IC.
The IC incorporates a built-in thermal shutdown circuit (TSD circuit). The thermal shutdown circuit (TSD circuit) is designed only
This IC is a monolithic IC that has a P- board and P+ isolation for the purpose of keeping distance between elements. A P-N junction
is formed between the P-layer and the N-layer of each element, and various types of parasitic elements are then formed.
For example, an application where a resistor and a transistor are connected to a terminal (shown in Fig.15):
elements in the proximity of the aforementioned parasitic diode.
Parasitic elements are structurally inevitable in the IC due to electric potential relationships. The operation of parasitic elements induces
the interference of circuit operations, causing malfunctions and possibly the destruction of the IC. Please be careful not to use the IC in
a way that would cause parasitic elements to operate. For example, by applying a voltage that is lower than the GND (P-board) to
the input terminal.
a parasitic diode.
P
＋
P-board
Resistor
N
P
Parasitic element
P
＋
N
Fig - 15 Simplified structure of a Bipolar IC
（Terminal B）
Ｎ
Parasitic element
P
＋
C
Transistor (NPN)
REV. D
P-board
B
N
N
P
GND
E
P
＋
N
GND
（TerminalＡ）
GND
Parasitic element
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