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

Rev.1.0 Nov.21 2011

AX6618

VOUT

Output of the regulator. Please connect Pin 3 and Pin 4 (SOP-8L-EP) using wide

tracks. It is necessary to connect an output capacitor with this pin for closed-loop

compensation and improving transient responses.



FUNCTION DESCRIPTIONS

Power-On-Reset

A Power-On-Reset (POR) circuit monitors both input voltages at VCNTL and VIN pins

to prevent wrong logic controls. The POR function initiates a soft-start process after the

two supply voltages exceed their rising POR threshold voltages during powering on. The

POR function also pulls low the POK pin regardless the output voltage when the VCNTL

voltage falls below its falling POR threshold.

Internal Soft-Start

An internal soft-start function controls rise rate of the output voltage to limit the

current surge at start-up. The typical soft-start interval is about 2mS.

Output Voltage Regulation

An error amplifier working with a temperature compensated 0.5V reference and an

output NMOS regulates output to the preset voltage. The error amplifier designed with high

bandwidth and DC gain provides very fast transient response and less load regulation. It

compares the reference with the feedback voltage and amplifies the difference to drive the

output NMOS which provides load current from VIN to VOUT.

Current-Limit

The AX6618 monitors the current via the output NMOS and limits the maximum

current to prevent load and AX6618 from damages during overload or short circuit

conditions.