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TSZ02201-0RDR0GZ00310-1-2

© 2015 ROHM Co., Ltd. All rights reserved.

08.Jan.2015 Rev.001

www.rohm.com

TSZ22111 • 15 • 001

BU4551B BU4551BF BU4551BFV

Operational Notes – continued

11. Unused Input Pins

Input pins 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 pins should be connected to the

power supply or ground line.

12. Regarding the Input Pin of the IC

In the construction of this IC, P-N junctions are inevitably formed creating parasitic diodes or transistors. The

operation of these parasitic elements can result in mutual interference among circuits, operational faults, or physical

damage. Therefore, conditions which cause these parasitic elements to operate, such as applying a voltage to an

input pin lower than the ground voltage should be avoided. Furthermore, do not apply a voltage to the input pins

when no power supply voltage is applied to the IC. Even if the power supply voltage is applied, make sure that the

input pins have voltages within the values specified in the electrical characteristics of this IC.

13. Ceramic Capacitor

When using a ceramic capacitor, determine the dielectric constant considering the change of capacitance with

temperature and the decrease in nominal capacitance due to DC bias and others.

14. Area of Safe Operation (ASO)

Operate the IC such that the output voltage, output current, and power dissipation are all within the Area of Safe

Operation (ASO).