bd9180gul ROHM Co. Ltd., bd9180gul Datasheet - Page 13

• Manufacturer Part Number: bd9180gul
• Description: 1ch High Efficiency Step-down Switching Regulator
• Manufacturer: ROHM Co. Ltd.

●Cautions on use
1. Absolute Maximum Ratings
2. Electrical potential at GND
3. Short-circuiting between terminals, and mismounting
4.Operation in Strong electromagnetic field
5. Thermal shutdown protection circuit
6. Inspection with the IC set to a pc board
7. Input to IC terminals
8. Ground wiring pattern
If small-signal GND and large-current GND are provided, It will be recommended to separate the large-current GND pattern from the
small-signal GND pattern and establish a single ground at the reference point of the set PCB so that resistance to the wiring pattern
and voltage fluctuations due to a large current will cause no fluctuations in voltages of the small-signal GND. Pay attention not to
cause fluctuations in the GND wiring pattern of external parts as well.
This is a monolithic IC with P
N-layer of each element form a P-N junction, and various parasitic element are formed.
The structure of the IC inevitably forms parasitic elements, the activation of which may cause interference among circuits,
and/or malfunctions contributing to breakdown. It is therefore requested to take care not to use the device in such manner
that the voltage lower than GND (at P-substrate) may be applied to the input terminal, which may result in activation of
parasitic elements.
While utmost care is taken to quality control of this product, any application that may exceed some of the absolute maximum
ratings including the voltage applied and the operating temperature range may result in breakage. If broken, short-mode or
open-mode may not be identified. So if it is expected to encounter with special mode that may exceed the absolute
maximum ratings, it is requested to take necessary safety measures physically including insertion of fuses.
GND must be designed to have the lowest electrical potential In any operating conditions.
When mounting to pc board, care must be taken to avoid mistake in its orientation and alignment. Failure to do so may result
in IC breakdown. Short-circuiting due to foreign matters entered between output terminals, or between output and power
supply or GND may also cause breakdown.
Be noted that using the IC in the strong electromagnetic radiation can cause operation failures.
Thermal shutdown protection circuit is the circuit designed to isolate the IC from thermal runaway, and not intended to protect
and guarantee the IC. So, the IC the thermal shutdown protection circuit of which is once activated should not be used
thereafter for any operation originally intended.
If a capacitor must be connected to the pin of lower impedance during inspection with the IC set to a pc board, the capacitor
must be discharged after each process to avoid stress to the IC. For electrostatic protection, provide proper grounding to
assembling processes with special care taken in handling and storage. When connecting to jigs in the inspection process,
be sure to turn OFF the power supply before it is connected and removed.
If a resistor is joined to a transistor terminal as shown in Fig 39.
Parasitic element
○if GND>Terminal B (at NPN transistor side),
○P-N junction works as a parasitic diode if the following relationship is satisfied; GND>Terminal A (at resistor side), or
Pin A
GND>Terminal B (at transistor side); and
a parasitic NPN transistor is activated by N-layer of other element adjacent to the above-mentioned parasitic diode.
N
P
+
N
GND
P
P substrate
P
+
+
N
Resistor
isolation between P-substrate and each element as illustrated below. This P-layer and the
Pin A
Fig.39 Simplified structure of monorisic IC
Parasitic
element
Parasitic element
13/14
Pin B
N
P
+
C
B
N
E
GND
P
P substrate
Transistor (NPN)
P
+
N
GND
Other adjacent elements
Pin B
B
C
E
GND
Parasitic
element