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XC9220/XC9221

Series

<Soft-Start Time>

The XC9220/XC9221B and D series can adjust the soft-start time externally via the CE pin. The soft-start function

operates until the CE pin voltage becomes 2.6V. Please refer to the following equation for calculating the soft-start

time. Minimum soft-start time is equal to the time set internally.

CE/CSS PIN

VCE

Rss

Css

CE/CSS

PIN

VCE

Rss

Css

ON/OFF

Signal

> Circuit Examle2 : CMOS logic (low current dissipation)

CE/CSS

PIN

VCE

Rss

Css

ON/OFF

Signal

> Cicuit Examle3 : CMOS logic (low current dissipation, quick off)

> Circuit Example1 : N-ch Open Drain

CE/CSS

PIN

VCE

Rss

Css

ON/OFF

Signal

Internal

sotf-starttime:Tss1

(XC9220/21A series)

Externallyset

soft-starttime:Tss2

(XC9220/21A series)

Minimum soft-start time

when externallyset:

Tss2_min =Tss1

XC9220/21A series

XC9220/21B series

<U.V.L.O. (Under Voltage Lock Out) >

When the input voltage becomes 2.3V (TYP.) or lower, the external P-channel driver transistor is forced OFF. Once

the U.V.L.O. operates, the XC9220/XC9221A and C series (soft-start internally set type) resets the internal circuit. For

this, by releasing the U.V.L.O. function, the IC performs the soft-start function to initiate output startup operation.

When the input voltage falls because of a power cutoff etc. and the IC stops operation due to the U.V.L.O. function, the

IC resumes its operation by internal soft-start circuit of the XC9220/XC9221B and D series. If the soft-start time is

●U.V.L.O. Operation

VIN

U.V.L.O. ( InternalSignal)

VOUT

(XC9220/21A and C series)

VOUT

(XC9220/21B and D series)

U.V.L.O.

release delay

Soft-start time: Tss1

U.V.L.O. operation

U.V.L.O.

release delay

Soft-start time (Externally set-up) :Tss2

Soft-start time:Tss1

■OPERATIONAL EXPLANATION (Continued)