BD8152FVM_11 Datasheet, PDF (15/18 Pages) Rohm – High-efficiency Step-up Switching Regulators with Built-in Power MOSFET

BD8152FVM, BD8158FVM
Technical Note
6) Testing on application boards
When testing the IC on an application board, connecting a capacitor to a pin with low impedance subjects the IC to stress.
Always discharge capacitors after each process or step. Ground the IC during assembly steps as an antistatic measure,
and use similar caution when transporting or storing the IC. Always turn the IC's power supply off before connecting it to or
removing it from a jig or fixture during the inspection process.
7) Ground wiring patterns
When using both small signal and large current GND patterns, it is recommended to isolate the two ground patterns,
placing a single ground point at the application's reference point so that the pattern wiring resistance and voltage
variations caused by large currents do not cause variations in the small signal ground voltage. Be careful not to change the
GND wiring patterns of any external components.
8) This monolithic IC contains P+ isolation and P substrate 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 the resistors and transistors are connected to the pins as shown in Fig. 35, a parasitic diode or a
transistor operates by inversing the pin voltage and GND voltage.
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 a way that will
trigger the operation of parasitic elements, such as the application of voltages lower than the GND (P substrate) voltage to
input and output pins.
(Pin A)
Resistor
(Pin B)
Transistor (NPN)
B
C
E
(Pin B)
B
C
P＋
N
P
N
P＋
N
P＋
N
N
P
N
GND
P＋
N
(Pin A)
E
GND
Parasitic elements
P
Parasitic element
P substrate
GND
Parasitic elements
GND
Parasitic
element
GND
Fig.35 Example of a Simple Monolithic IC
9) Overcurrent protection circuits
An overcurrent protection circuit designed according to the output current is incorporated for the prevention of IC
destruction that may result in the event of load shortning. This protection circuit is effective in preventing damage due to
sudden and unexpected accidents. However, the IC should not be used in applications characterized by the continuous
operation or transitioning of the protection circuits. At the time of thermal designing, keep in mind that the current capability
has negative characteristics to temperatures.
10) Thermal shutdown circuit (TSD)
This IC incorporates a built-in TSD circuit for the protection from thermal destruction. The IC should be used within the
specified power dissipation range. However, in the event that the IC continues to be operated in excess of its power
dissipation limits, the attendant rise in the chip's temperature Tj will trigger the temperature protection circuit to turn off all
output power elements. The circuit automatically resets once the chip's temperature Tj drops. Operation of the TSD circuit
presumes that the IC's absolute maximum ratings have been exceeded. Application designs should never make use of the
TSD circuit.
11) Testing on application boards
At the time of inspection of the installation boards, when the capacitor is connected to the pin with low impedance, be sure
to discharge electricity per process because it may load stresses to the IC. Always turn the IC's power supply off before
connecting it to or removing it from a jig or fixture during the inspection process. Ground the IC during assembly steps as
an antistatic measure, and use similar caution when transporting or storing the IC.
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15/17
2011.08 - Rev.C