XC9268 datasheet(14/30 Pages) TOREX

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XC9268 Series

■OPERATIONAL EXPLANATION(Continued)

<Soft-start function>

The output voltage of XC9268 rises with soft start by slowly raising the reference voltage. The rise time of this reference

voltage is the soft start time. The soft-start time is set to tss1 (TYP. 2.0ms) which is fixed internally or to the time set by adding a

capacitor and a resistor to the EN / SS pin whichever is later.

The thermal shutdown (TSD) as an over temperature limit is built in the XC9268 series.

When the junction temperature reaches the detection temperature, the driver transistor is forcibly turned off. When the junction

temperature falls to the release temperature while in the output stop state, restart takes place by soft-start.

<UVLO>

When the VIN pin voltage falls below VUVLO1 (TYP. 2.7V), the driver transistor is forcibly turned off to prevent false pulse output

due to instable operation of the internal circuits. When the VIN pin voltage rises above VUVLO2 (TYP. 2.8V), the UVLO function is

released, the soft-start function activates, and output start operation begins. Stopping by UVLO is not shutdown; only pulse

output is stopped and the internal circuits continue to operate.

On USP-6C Package, the output state can be monitored using the power good function. The PG pin is an Nch open drain

output, therefore a pull-

up resistance (approx. 100kΩ) must be connected to the PG pin.

CONDITIONS

SIGNAL

EN/SS=H

VFB＞VPGDET

H (High impedance)

VFB≦VPGDET

L (Low impedance)

Thermal Shutdown

L (Low impedance)

UVLO（VIN<VUVLOD)

Undefined State

EN/SS=L

Stand-by

L (Low impedance)

XC9268 Datasheet(PDF) 14 Page - Torex Semiconductor