BA829

Technical Note

6/7

www.rohm.com

2009.06 - Rev.A

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

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Operation Notes

1. Absolute maximum ratings

An excess in the absolute maximum ratings, such as supply voltage, temperature range of operating conditions, etc., can break

down the devices, thus making impossible to identify breaking mode, such as a short circuit or an open circuit. If any over rated

values will expect to exceed the absolute maximum ratings, consider adding circuit protection devices, such as fuses.

2. Connecting the power supply connector backward

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

lines. An external direction diode can be added.

3. Power supply lines

Design PCB layout pattern to provide low impedance GND and supply lines. To obtain a low noise ground and supply line,

separate the ground section and supply lines of the digital and analog blocks. Furthermore, for all power supply terminals

to ICs, connect a capacitor between the power supply and the GND terminal. When applying electrolytic capacitors in the

circuit, note that capacitance characteristic values are reduced at low temperatures.

4. GND voltage

The potential of GND pin must be minimum potential in all operating conditions.

5. Inter-pin shorts and mounting errors

Use caution when positioning the IC for mounting on printed circuit boards. The IC may be damaged if there is any

connection error or if pins are shorted together.

6. Actions in strong electromagnetic field

Use caution when using the IC in the presence of a strong electromagnetic field as doing so may cause the IC to malfunction.

7. 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. 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. Use similar precaution when transporting or storing the IC.

8. Regarding input pin of the IC

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, creating a parasitic diode

or transistor. For example, the relation between each potential is as follows:

When GND > Pin A and GND > Pin B, the P-N junction operates as a parasitic diode.

When GND > Pin B, the P-N junction operates as a parasitic transistor.

Parasitic diodes can occur inevitable in the structure of the IC. The operation of parasitic diodes can result in mutual

interference among circuits, operational faults, or physical damage. Accordingly, methods by which parasitic diodes

operate, such as applying a voltage that is lower than the GND (P substrate) voltage to an input pin, should not be used.

9. Ground Wiring Pattern

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 ground potential of application 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 pattern of any external components, either.

Resistor

Transistor (NPN)

N

N

N

P

+

P

+

P

P substrate

GND

Parasitic element

Pin A

N

N

P

+

P

+

P

P substrate

GND

Parasitic element

Pin B

C

B

E

N

GND

Pin A

Parasitic

element

Pin B

Other adjacent elements

E

B

C

GND

Parasitic

element

Fig.5 Example of IC structure