NJW4104
*Input Capacitor CIN
The input capacitor CIN is required in order to prevent oscillation and reduce power supply ripple of applications when high
power supply impedance or a long power supply line.
Therefore, the recommended capacitance (refer to conditions of ELECTRIC CHARACTERISTIC) or larger input capacitor,
connected between VIN and GND as short path as possible, is recommended in order to avoid the problem.
*Output Capacitor CO
The output capacitor CO is required for a phase compensation of the internal error amplifier, and the capacitance and the
equivalent series resistance (ESR) influence stable operation of the regulator.
If use a smaller output capacitor than the recommended capacitance (refer to conditions of ELECTRIC CHARACTERISTIC),
it may cause excess output noise or oscillation of the regulator due to lack of the phase compensation. Therefore, the
recommended capacitance or larger output capacitor, connected between VOUT and GND as short path as possible, is
recommended for stable operation. The recommended capacitance may be different by output voltage, therefore confirm the
recommended capacitance of the required output voltage.
Furthermore, a larger output capacitor reduces output noise and ripple output, and also improves Output Transient Response
when a load changes rapidly.
Selecting the output capacitor, should consider varied characteristics of a capacitor: frequency characteristics, temperature
characteristics, DC bias characteristics and so on. Therefore, the capacitor that has a sufficient margin of the rated voltage
against the output voltage and superior temperature characteristics, is recommended for CO.
*Transient Response of Output Voltage
In general, the regulator tends to cause overshoot or undershoot of output voltage at the following conditions.
Particularly in products featuring low current consumption, the output voltage fluctuation may become large due to product
characteristics.
When input voltage or output current fluctuate sharply
When output capacitance is small
When output load is light
When start up from the condition of narrow voltage difference between an Input and an output.
One way to improve transient response is to use a large capacity input and output capacitors to suppress to the fluctuation.
Amount of transient fluctuation will change according to multiple conditions, so please refer to the above to confirm with actual
equipment.
Ver.1.0
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