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Datasheet

Datasheet

BD555BKFV

TSZ02201-0W1W0C300010-1-2

© 2013 ROHM Co., Ltd. All rights reserved.

30.July.2013 Rev.003

www.rohm.com

TSZ22111

・15・001

Operational Notes – continued

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.

12.

Regarding the 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 the P layers with the N layers of other elements, creating a

parasitic diode or transistor. For example (refer to figure below):

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

interference among circuits, operational faults, or physical damage. Therefore, conditions that cause these diodes to

operate, such as applying a voltage lower than the GND voltage to an input pin (and thus to the P substrate) should

be avoided.

Figure xx. Example of monolithic IC structure

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).

15.

Thermal Shutdown Circuit(TSD)

This IC has a built-in thermal shutdown circuit that prevents heat damage to the IC. Normal operation should always

be within the IC’s power dissipation rating. If however the rating is exceeded for a continued period, the junction

temperature (Tj) will rise which will activate the TSD circuit that will turn OFF all output pins. When the Tj falls below

the TSD threshold, the circuits are automatically restored to normal operation.

Note that the TSD circuit operates in a situation that exceeds the absolute maximum ratings and therefore, under no

circumstances, should the TSD circuit be used in a set design or for any purpose other than protecting the IC from

heat damage.

16.

Over Current Protection Circuit (OCP)

This IC incorporates an integrated overcurrent protection circuit that is activated when the load is shorted. This

protection circuit is effective in preventing damage due to sudden and unexpected incidents. However, the IC should

not be used in applications characterized by continuous operation or transitioning of the protection circuit.