BD9422EFV_15 Datasheet, PDF (24/30 Pages) Rohm – White LED Driver for large LCD panel

BD9422EFV
Datasheet
●Operational Notes
1.) This product is produced with strict quality control, but might be destroyed if used beyond its absolute maximum ratings including
the range of applied voltage or operation temperature. Failure status such as short-circuit mode or open mode can not be
estimated. If a special mode beyond the absolute maximum ratings is estimated, physical safety countermeasures like fuse
needs to be provided.
2.) Connecting the power line to IC in reverse polarity (from that recommended) may cause damage to IC. For protection against
damage caused by connection in reverse polarity, countermeasures, installation of a diode between external power source and IC
power terminal, for example, needs to be taken.
3.) When this product is installed on a printed circuit board, attention needs to be paid to the orientation and position of IC. Wrong
installation may cause damage to IC. Short circuit caused by problems like foreign particles entering between outputs or
between an output and power GND also may cause damage.
4.) Since the back electromotive force of external coil causes regenerated current to return, countermeasures like installation of a
capacitor between power source and GND as the path for regenerated current needs to be taken. The capacitance value must
be determined after it is adequately verified that there is no problem in properties such that the capacity of electrolytic capacitor
goes down at low temperatures. Thermal design needs to allow adequate margin in consideration of allowable loss (Pd) in
actual operation state.
5.) The GND pin needs to be at the lowest potential in any operation state.
6.) Thermal design needs to be done with adequate margin in consideration of allowable loss (Pd) in actual operation state.
7.) Use in a strong magnetic field may cause malfunction.
8.) Output Tr needs to not exceed the absolute maximum rating and ASO while using this IC. As CMOS IC and IC which has several
power sources may undergo instant flow of rush current at turn-on, attention needs to be paid to the capacitance of power source
coupling, power source, and the width and run length of GND wire pattern.
9.) This IC includes temperature protection circuit (TSD circuit). Temperature protection circuit (TSD circuit) strictly aims blockage of
IC from thermal runaway, not protection or assurance of IC. Therefore use assuming continuous use and operation after this
circuit is worked needs to not be done.
10.) As connection of a capacitor with a pin with low impedance at inspection of a set board may cause stress to IC, discharge needs
to be performed every one process. Before a jig is connected to check a process, the power needs to be turned off absolutely.
Before the jig is removed, as well, the power needs to be turned off.
11.) This IC is a monolithic IC which has P+ isolation for separation of elements and P board between elements.
A P-N junction is formed in this P layer and N layer of elements, composing various parasitic elements.
For example, a resistance and transistor are connected to a terminal as shown in the figure,
○ When GND>(Terminal A) in the resistance and when GND>(Terminal B) in the transistor (NPN), P-N junction operates
as a parasitic diode.
○ When GND>(Terminal B) in the transistor (NPN), parasitic NPN transistor operates in N layer of other elements nearby
the parasitic diode described before.
Parasitic elements are formed by the relation of potential inevitably in the structure of IC. Operation of parasitic elements can
cause mutual interference among circuits , malfunction as well as damage. Therefore such use as will cause operation of
parasitic elements like application of voltage on the input terminal lower than GND (P board) need to not be done.
(Pin A)
Resistor
(Pin B)
Transistor (NPN)
B
C
E
P
N
P
N
P
N
P substrate
GND
Parasitic element
P
N
N
P
N
P substrate
GND
P
N
GND
Parasitic element
(Pin B)
(Pin A)
BC
E
Parasitic element
ＧＮＤ
GND
Adjacent other elements
Parasitic
Figure 32. Example of Simple Structure of Monolithic IC
Status of this document
The Japanese version of this document is formal specification. A customer may use this translation version only for a reference
to help reading the formal version.
If there are any differences in translation version of this document formal version takes priority.
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1.Sep.2015 Rev.006