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Axelite Confidential Materials, do not copy or distribute without written consent.

Rev.1.5 Oct.16, 2019

AX3121



FUNCTION DESCRIPTIONS

PWM Control

The AX3121 consists of DC/DC converters that employ a synchronous pulse-width

modulation (PWM) system. In converters of the AX3121, the pulse width varies in a range

from 0 to 100%, according to the load current. The ripple voltage produced by the switching

can easily be removed through a filter because the switching frequency remains constant.

Therefore, these converters provide a low-ripple power over broad ranges of input voltage

and load current.

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:











 





5

2

1

62

0

R

R

V

V

OUT

.

Table 1 Resistor select for output voltage setting

VOUT

R5

R2

5.0V

4.7K

33K

3.3V

3K

13K

2.5V

3.3K

10K

1.8V

6.8K

13K

1.5V

3.3K

4.7K

1.184V

3.3K

3.0K

1.0V

3.3K

2.0K

COMP

Compensation pin. For EL output capacitor application, the COMP pin connects R4

and C9 to GND for all condition and for MLCC output capacitor application, the COMP

connects R4 and C8 to FB, please refer the application circuit table.