Technical Note

11/12

BD2270HFV

www.rohm.com

2009.04 - Rev.A

© 2009 ROHM Co., Ltd. All rights reserved.

(5)

GND voltage

Make setting of the potential of the GND terminal so that it will be maintained at the minimum in any operating state.

Furthermore, check to be sure no terminals are at a potential lower than the GND voltage including an actual electric

transient.

(6)

Short circuit between terminals and erroneous mounting

In order to mount ICs on a set PCB, pay thorough attention to the direction and offset of the ICs. Erroneous mounting can

break down the ICs. Furthermore, if a short circuit occurs due to foreign matters entering between terminals or between

the terminal and the power supply or the GND terminal, the ICs can break down.

(7)

Operation in strong electromagnetic field

Be noted that using ICs in the strong electromagnetic field can malfunction them.

(8)

Inspection with set PCB

On the inspection with the set PCB, if a capacitor is connected to a low-impedance IC terminal, the IC can suffer stress.

Therefore, be sure to discharge from the set PCB by each process. Furthermore, in order to mount or dismount the set

PCB to/from the jig for the inspection process, be sure to turn OFF the power supply and then mount the set PCB to the jig.

After the completion of the inspection, be sure to turn OFF the power supply and then dismount it from the jig. In addition,

for protection against static electricity, establish a ground for the assembly process and pay thorough attention to the

transportation and the storage of the set PCB.

(9)

Input terminals

In terms of the construction of IC, parasitic elements are inevitably formed in relation to potential. The operation of the

parasitic element can cause interference with circuit operation, thus resulting in a malfunction and then breakdown of the

input terminal. Therefore, pay thorough attention not to handle the input terminals, such as to apply to the input terminals a

voltage lower than the GND respectively, so that any parasitic element will operate. Furthermore, do not apply a voltage to

the input terminals when no power supply voltage is applied to the IC. In addition, even if the power supply voltage is

applied, apply to the input terminals a voltage lower than the power supply voltage or within the guaranteed value of

electrical characteristics.

(10) 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.

(11) External capacitor

In order to use a ceramic capacitor as the external capacitor, determine the constant with consideration given to a

degradation in the nominal capacitance due to DC bias and changes in the capacitance due to temperature, etc.

(12) Thermal design Perform thermal design in which there are adequate margins by taking into account the power

dissipation (Pd) in actual states of use.