RH5RI251B 查看數據表（PDF） - RICOH Co.,Ltd.
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RH5RI251B Datasheet PDF : 24 Pages
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RH5RI
APPLICATION HINTS
When using these ICs, be sure to take care of the following points :
• Set external components as close as possible to the IC and minimize the connection between the com-
ponents and the IC. In particular, when an external component is connected to OUT Pin, make mini-
mum connection with the capacitor.
• Make sufficient grounding. A large current flows through Vss Pin by switching. When the impedance
of the Vss connection is high, the potential within the IC is varied by the switching current. This
mayresult in unstable operation of the IC.
• Use capacitor with a capacity of 10µF or more, and with good high frequency characteristics such as
tantalum capacitor. We recommend the use of a capacitor with an allowable voltage which is at least
three times the output set voltage. This is because there may be the case where a spike-shaped high
voltage is generated by the inductor when Lx transistor is turned off.
• Take the utmost care when choosing an inductor. Namely, choose such an inductor that has sufficient-
ly small d.c. resistance and large allowable current, and hardly reaches magnetic saturation. When
the inductance value of the inductor is small, there may be the case where ILX exceeds the absolute
maximum ratings at the maximum load. Use an inductor with an appropriate inductance (refer to
Selectionof peripheral components).
• Use a diode of a Schottky type with high switching speed, and also take care of the rated current (refer
to Selection of peripheral components).
The performance of power source circuits using these ICs largely depends upon the peripheral components. Take the utmost care
in the selection of the peripheral components. In particular, design the peripheral circuits in such a manner that the values such as volt-
age, current and power of each component, PCB patterns and the IC do not exceed their respective rated values.
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