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

Rev.1.9 Oct.30, 2019

AX3513



APPLICATION CIRCUIT

VOUT = 0.6 * (1+R1/R2)

R2

300K

C1

4.7u

C2

10u

VOUT=1.8V

R2=100K~330K

L1

2.2uH

R1

600K

U1

AX3513

VIN

EN

GND

SW

FB

C3

15p

VIN=2.5V~5.5V



FUNCTION DESCRIPTIONS

Operation

AX3513 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 0.6V. It operates at a fixed switching frequency, and uses the slope

compensated current mode architecture. This step-down DC-DC Converter supplies

minimum 1000mA output current at input voltage range from 2.5V 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 transient 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.