ZXSC410/ZXSC420/ZXSC440

Document number: DS33618 Rev. 6 - 2

6 of 17

www.diodes.com

August 2015

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ZXSC410/ZXSC420/ZXSC440

External Component Selection

Switching Transistor Selection

transistor is switched off. Diodes SOT26 transistors are an ideal choice for this application.

Schottky Diode Selection

As with the switching transistor, the Schottky rectifier diode has a major impact on the converter efficiency. A Schottky diode with a low forward

voltage and fast recovery time should be used for this application.

The diode should be selected so that the maximum forward current rating is greater or equal to the maximum peak current in the inductor, and

the maximum reverse voltage is greater or equal to the output voltage. The Diodes ZHCS Series meets these needs.

Inductor Selection

The inductor value must be chosen to satisfy performance, cost and size requirements of the overall solution.

Inductor selection has a significant impact on the converter performance. For applications where efficiency is critical, an inductor with a series

resistan

ce of 500mΩ or less should be used.

Output Capacitors

Output capacitors are a critical choice in the overall performance of the solution. They are required to filter the output and supply load transient

solution.

The ESR of the output capacitor can also affect loop stability and transient performance. The capacitors selected for the solutions and indicated

in the reference designs are optimized to provide the best overall performance.

Input Capacitors

The input capacitor is chosen for its voltage and RMS current rating. The use of low ESR electrolytic or tantalum capacitors is recommended.

Capacitor values for optimum performance are suggested in the reference design section.

2

ESR.

Peak Current Definition

determined by:

I

V

R

PK

SENSE

Sense Resistor