12/30

XC9281/XC9282 Series

■OPERATIONAL EXPLANATION (Continued)

＜100% Duty cycle mode＞

In conditions where the input-output voltage difference is small or transient response, the Pch MOS driver transistor might keep

on turning on and the 100% duty cycle mode might be set. The 100% duty cycle mode achieves high output voltage stability and

highspeed response even under full load conditions and the condition where the input-output voltage difference is small.

＜CE function＞

When "H" voltage (VCEH) is fed to the CE pin, normal operation starts after raising the output voltage with the soft start function.

When the "L" voltage (VCEL) is fed to the CE pin, it enters the standby state and the current consumption is suppressed to 0

μA

(TYP.). Additionally, Pch MOS driver transistor and Nch MOS driver transistor are turned off.

＜Soft-Start function＞

It is a function to raise the output voltage gradually and suppress inrush current. After the "H" voltage (VCEH) is fed to the CE pin,

the reference voltage which is connected to the error amplifier increases linearly during the soft start period. As a result, the output

voltage increases in proportion to the increase of the reference voltage. This operation can prevent a large inrush current and

smoothly raise the output voltage.

tSS

VOUT(T) x 90%

VCE

VOUT

0V

0V

VCEH