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BD9102FVM BD9104FVM

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© 2012 ROHM Co., Ltd. All rights reserved.

TSZ22111･14･001

TSZ02201-0J3J0AJ00340-1-2

24.Oct.2013 Rev.003

Operational Notes

1. Reverse Connection of Power Supply

Connecting the power supply in reverse polarity can damage the IC. Take precautions against reverse polarity when

connecting the power supply, such as mounting an external diode between the power supply and the IC’s power supply

terminals.

2. Power Supply Lines

Design the PCB layout pattern to provide low impedance supply lines. Separate the ground and supply lines of the

digital and analog blocks to prevent noise in the ground and supply lines of the digital block from affecting the analog

block. Furthermore, connect a capacitor to ground at all power supply pins. Consider the effect of temperature and aging

on the capacitance value when using electrolytic capacitors.

3. Ground Voltage

Ensure that no pins are at a voltage below that of the ground pin at any time, even during transient condition.

4. Ground Wiring Pattern

When using both small-signal and large-current GND traces, the two ground traces should be routed separately but

connected to a single ground at the reference point of the application board to avoid fluctuations in the small-signal

ground caused by large currents. Also ensure that the ground traces of external components do not cause variations on

the ground voltage. The ground lines must be as short and thick as possible to reduce line impedance.

5. Thermal Consideration

Should by any chance the power dissipation rating be exceeded, the rise in temperature of the chip may result in

deterioration of the properties of the chip. The absolute maximum rating of the Pd stated in this specification is when the

IC is mounted on a 70mm x 70mm x 1.6mm glass epoxy board. In case of exceeding this absolute maximum rating,

increase the board size and copper area to prevent exceeding the Pd rating.

6. Recommended Operating Conditions

These conditions represent a range within which the expected characteristics of the IC can be approximately obtained.

The electrical characteristics are guaranteed under the conditions of each parameter.

7. Inrush Current

When power is first supplied to the IC, it is possible that the internal logic may be unstable and inrush current may flow

instantaneously due to the internal powering sequence and delays, especially if the IC has more than one power supply.

Therefore, give special consideration to power coupling capacitance, power wiring, width of ground wiring, and routing

of connections.

8. Operation Under Strong Electromagnetic Field

Operating the IC in the presence of a strong electromagnetic field may cause the IC to malfunction.

9. Testing on Application Boards

When testing the IC on an application board, connecting a capacitor directly to a low-impedance output pin may subject

the IC to stress. Always discharge capacitors completely after each process or step. The IC’s power supply should

always be turned OFF completely before connecting or removing it from the test setup during the inspection process. To

prevent damage from static discharge, ground the IC during assembly and use similar precautions during transport and

storage.

10. Inter-Pin Short and Mounting Errors

Ensure that the direction and position are correct when mounting the IC on the PCB. Incorrect mounting may result in

damaging the IC. Avoid nearby pins being shorted to each other especially to ground. Inter-pin shorts could be due to

many reasons such as metal particles, water droplets (in very humid environment) and unintentional solder bridge

deposited in between pins during assembly to name a few.

11. Unused Input Terminals

Input terminals of an IC are often connected to the gate of a MOS transistor. The gate has extremely high impedance

and extremely low capacitance. If left unconnected, the electric field from the outside can easily charge it. The small

charge acquired in this way is enough to produce a significant effect on the conduction through the transistor and cause

unexpected operation of the IC. So unless otherwise specified, unused input terminals should be connected to the

power supply or ground line.

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