BD9528AMUV Datasheet, PDF (27/30 Pages) Rohm – High Performance Regulators for PCs Main Power Supply for Notebook PCs(With Built-in Linear Regulator)

BD9528AMUV
Technical Note
●Operation Notes and Precautions
1. This integrated circuit is a monolithic IC, which (as shown in the figure below), has P⁺ isolation in the P substrate and
between the various pins. A P-N junction is formed from this P layer and N layer of each pin, with the type of junction
depending on the relation between each potential, as follows:
・When GND＞ element A＞ element B, the P-N junction is a diode.
・When element B＞GND element A, the P-N junction operates as a parasitic transistor.
Parasitic diodes inevitably occur in the structure of the IC. The operation of parasitic diodes can result in mutual
interference among circuits, as well as operating malfunctions and physical damage. Therefore, be careful to avoid
methods by which parasitic diodes operate, such as applying a voltage lower than the GND (P substrate) voltage to an
input pin.
Resistor
Transistor (NPN)
Pin A
Pin B _C ^B
Pin B
Pin A
E
N ^{P+ N}
Parasitic element
P
P⁺ _N
P substrate
GND
Parasitic
element
N _P+
N
P
P⁺ _N
P substrate
Parasitic element ^GND
GND
B
C
E
Parasitic
element
GND
Other adjacent elements
2. In some modes of operation, power supply voltage and pin voltage are reversed, giving rise to possible internal circuit
damage. For example, when the external capacitor is charged, the electric charge can cause a VCC short circuit to the
GND. In order to avoid these problems, inserting a VCC series countercurrent prevention diode or bypass diode
between the various pins and the VCC is recommended.
Bypass diode
Counter current prevention diode
VCC
Pin
3. Absolute maximum rating
Although the quality of this IC is rigorously controlled, the IC may be destroyed when applied voltage or operating
temperature exceeds its absolute maximum rating. Because short mode or open mode cannot be specified when the IC
is destroyed, it is important to take physical safety measures such as fusing if a special mode in excess of absolute
rating limits is to be implemented.
4. GND potential
Make sure the potential for the GND pin is always kept lower than the potentials of all other pins, regardless of the
operating mode.
5. Thermal design
In order to build sufficient margin into the thermal design, give proper consideration to the allowable loss (Power
Dissipation) in actual operation.
6. Short-circuits between pins and incorrect mounting position
When mounting the IC onto the circuit board, be extremely careful about the orientation and position of the IC. The IC
may be destroyed if it is incorrectly positioned for mounting. Do not short-circuit between any output pin and supply pin
or ground, or between the output pins themselves. Accidental attachment of small objects on these pins will cause
shorts and may damage the IC.
7. Operation in strong electromagnetic fields
Use in strong electromagnetic fields may cause malfunctions. Use extreme caution with electromagnetic fields.
8. Thermal shutdown circuit
This IC is provided with a built-in thermal shutdown (TSD) circuit, which is activated when the operating temperature
reaches 175℃ (standard value), and has a hysteresis range of -15℃ (standard value). When the IC chip temperature
rises to the threshold, all the inputs automatically turn OFF. Note that the TSD circuit is provided for the exclusive
purpose shutting down the IC in the presence of extreme heat, and is not designed to protect the IC per se or guarantee
performance when or after extreme heat conditions occur. Therefore, do not operate the IC with the expectation of
continued use or subsequent operation once the TSD is activated.
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2011.11 - Rev.A