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

Rev.1.0 Nov.21 2011

AX6618

Under-Voltage Protection (UVP)

The AX6618 monitors the voltage on FB pin after soft-start process is finished.

Therefore the UVP is disabling during soft-start. When the voltage on FB pin falls below the

under-voltage threshold, the UVP circuit shuts off the output immediately. After a while, the

AX6618 starts a new soft-start to regulate output.

Thermal Shutdown

A thermal shutdown circuit limits the junction temperature of AX6618. When the

junction temperature exceeds +160°C, a thermal sensor turns off the output NMOS,

allowing the device to cool down. The regulator regulates the output again through

initiation of a new soft-start cycle after the junction temperature cools by 50°C, resulting in

a pulsed output during continuous thermal overload conditions. The thermal shutdown

designed.