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Rev.1.1 Oct.16, 2019

AX3165/A



APPLICATION INFORMATION

Setting the Output Voltage

Application circuit item shows the basic application circuit with adjustable output

version. The external resistor sets the output voltage according to the following equation:

)

4

R

1

R

+

1

(

×

V

0

.

1

=

VOUT

Table 1 Resistor select for output voltage setting

VOUT

R4

R1

5V

1.5K

6K

3.3V

1.3K

3K

Inductor Selection

For most designs, the different frequency can be reducing the inductor value; The

AX3165/A is suggested 33µH. Where is inductor Ripple Current. Large value inductors

lower ripple current and small value inductors result in high ripple currents. Choose

inductor ripple current approximately 20% of the maximum load current 2A, ΔIL=0.4A. The

DC current rating of the inductor should be at least equal to the maximum load current plus

half the ripple current to prevent core saturation (2A+0.2A).

Input Capacitor Selection

This capacitor should be located close to the IC using short leads and the voltage

rating should be approximately 1.5 times the maximum input voltage. The RMS current

rating requirement for the input capacitor of a buck regulator is approximately 1⁄2 the DC

load current. A low ESR input capacitor sized for maximum RMS current must be used. A

470µF low ESR capacitor for most applications is sufficient.

Output Capacitor Selection

The output capacitor is required to filter the output and provide regulator loop stability.

The important capacitor parameters are; the 100 KHz Equivalent Series Resistance (ESR),

the RMS ripples current rating, voltage rating, and capacitance value. For the output

capacitor, the ESR value is the most important parameter. The ESR can be calculated from

the following formula.

ESR

I

V

L

RIPPLE







= 0.4A x 80mΩ= 32mV