R1230D331C-TL View Datasheet(PDF) - RICOH Co.,Ltd.
Part Name
Description
Manufacturer
R1230D331C-TL Datasheet PDF : 20 Pages
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n External Components
1. Inductor
Select an inductor that peak current does not exceed ILmax. If larger current than allowable current flows, magnetic
saturation occurs and make transform efficiency worse.
Supposed that the load current is at the same, the smaller value of L is used, the larger the ripple current is.
Provided that the allowable current is large in that case and DC current is small, therefore, for large output current,
efficiency is better than using an inductor with a large value of L and vice versa.
2. Capacitor
As for CIN, use a capacitor with low ESR (Equivalent Series Resistance) Ceramic type of a capacity at least 10µF for
stable operation.
COUT can reduce ripple of Output Voltage, therefore as much as 10µF tantalum type is recommended.
n TIMING CHART
CE pin Voltage
Internal Operational
Amplifier Output
Internal Soft-start
Set Voltage
Output
Short
Output Short
Internal Oscillator Waveform
Lx Pin Output
Soft-start Time
Stable
Latched
Delay Time of Protection
The timing chart as shown above describes the waveforms starting from the IC is enabled with CE and latched with
protection. During the soft-start time, until the level is rising up to the internal soft-start set voltage, the duty cycle of Lx is
gradually wider and wider to prevent the over-shoot of the voltage. During the term, the output of amplifier is “H”, then after
the output voltage reaches the set output voltage, they are balanced with the stable state. Herein, if the output pin would
be short circuit, the output of amplifier would become “H” again, and the condition would continue for 1.5ms (TYP.), latch
circuit would work and the output of Lx would be latched with “OFF”. (Output =“High-Z”)
If the output short is released before the latch circuit works (within 1.5ms after output shorted), the output of amplifier is
balanced in the stable state again.
Once the IC is latched, to release the protection, input “L” with CE pin, or make the supply voltage at UVLO level or less.
Rev. 1.17
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