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

Rev.1.3 Nov.26, 2019

AX3518



APPLICATION CIRCUIT

VOUT = 0.8 * (1+R2/R3)

R3

600K

C1

22uF

C2

22uF

VOUT=1.2V

VIN=2.8 to 5.5V

R2 = 300K~820K

L1

2.2uH

R2

300K

AX3518

PVIN

EN

SGND

SW

FB

C5

15pF

SVIN

PGND

R1

10R

C3

100nF

C4

100nF

REF



FUNCTION DESCRIPTIONS

Operation

AX3518 is a monolithic switching mode Step-Down DC-DC converter. It utilizes internal

MOSFETs to achieve high efficiency and can generate very low output voltage by using

internal reference at 0.8V. It operates at a fixed switching frequency, and uses the slope

compensated current mode architecture. This Step-Down DC-DC Converter supplies

3200mA output current at input voltage range from 2.8V to 5.5V.

Current Mode PWM Control

Slope compensated current mode PWM control provides stable switching and

cycle-by-cycle current limit for excellent load and line responses and protection of the

internal main switch (P-CH MOSFET) and synchronous rectifier (N-CH MOSFET). During

normal operation, the internal P-CH MOSFET is turned on for a certain time to ramp the

inductor current at each rising edge of the internal oscillator, and switched off when the peak

inductor current is above the error voltage. The current comparator, ICOMP

, limits the peak

inductor current. When the main switch is off, the synchronous rectifier will be turned on

immediately and stay on until either the inductor current starts to reverse, as indicated by the

current reversal comparator, IZERO, or the beginning of the next clock cycle.