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Rev.1.5 Oct.15, 2019

AX3116

Input Capacitor

The input current to the step-down converter is discontinuous, and so a capacitor is

required to supply the AC current to the step-down converter while maintaining the DC input

voltage. A low-ESR capacitor is required to keep the noise at the IC to a minimum. The

low-ESR electrolytic capacitor may also suffice. The input capacitor value should be greater

than 470µF. However since it absorbs the input switching current it requires an adequate

ripple current rating. Its RMS current rating should be greater than approximately 1/2 of the

DC load current. For insuring stable operation CIN should be placed as close to the IC as

possible. Alternately a smaller high quality ceramic 0.1uF capacitor may be placed closer to

the IC and a larger capacitor placed further away. If using this technique, it is recommended

that the larger capacitor be a electrolytic type.

Output Capacitor

The output capacitor is required to maintain the DC output voltage. Low ESR capacitors

are preferred to keep the output voltage ripple low. The characteristics of the output capacitor

also affect the stability of the regulation control system. The low-ESR electrolytic capacitors

are recommended. The output capacitor value should be greater than 470µF.