7/13

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

Rev.1.4 Oct.16, 2019

AX3304/A

An aluminum electrolytic capacitor’s ESR value is related to the capacitance and its

voltage rating. In most case, higher voltage electrolytic capacitors have lower ESR values.

Most of the time, capacitors with much higher voltage ratings may be needed to provide

the low ESR values required for low output ripple voltage. System stability is depending on

output capacitor’s ESR, Correct to choose output capacitor’s ESR is very important. It is

recommended to using a 220~470µF, the ESR values range is 40~130mΩ.

EN/CT

The pin is enable/shutdown and auto restart control functions. When system is

normal operating, this pin is enable/shutdown function. Pulling this pin below a threshold

voltage of under 0.3V shuts the regulator off, and pulling this pin from 0.5V to 1.5V turns

the regulator on. However when VOUT is short (VFB<0.4V), the auto restart function can be

started that restart the regulator cycle by cycle. The cycle time is set by outside capacitor

(C6). Please refer the below waveform and formula, the t2 cycle is regulator off time and t1

cycle is current limit time. The charge-current is 30uA and discharge-current is 1.3uA.

VEN/CT

Time

t1

t2

Time

Iin (A)

0.5V

1.5V

0

Current Limit

Thermal Considerations

The SOP-8L package needs a heat sink under most conditions. The heat sink

connect exposed pad of AX3304/A to obtain best effect. The size of the heat sink depends

on the input voltage, the output voltage, the load current and the ambient temperature.