XCL301 datasheet(9/19 Pages) TOREX

9 / 19 page

9/19

XC9140 (Design Target)

XCL301

Series

■

OPERATIONAL EXPLANATION (Continued)

< CL Auto Discharge >

The XCL301 series allows high-speed discharge of the output capacitor (CL) through the IC internal CL discharge resistance

when an L level signal is input into the CE pin (when the IC is in the standby state). This makes it possible to prevent application

malfunctioning due to a charge remaining on CL when the IC is stopped. The discharge time is determined by the CL discharge

resistance and CL.

t = -τln ((VIN-V) /(VIN-VOUT(T)))

V: Output voltage after discharge

VOUT (T): Nominal output voltage

t: Unit: mm

Discharge time

: CL×RDCHG

CL: Capacitance of output capacitor

RDCHG: CL auto-discharge resistance

The XCL301 series can be put in the shutdown state by L level input to the CE pin. In the shutdown state, the supply current of

the IC is 0μA (TYP.). Operation is started by inputting H level to the CE pin. The CE pin input is CMOS input and the sink

current is 0μA (TYP.).

The rise time is determined by the input voltage, output voltage, output capacitance, and soft-start current limit (ILIMSS).

(1) When the CE pin is turned on, the driver transistor turns on.

(2) When the driver current exceeds the soft-start current limit value, the driver transistor is turned off.

(3) The driver transistor remains off until the inductor current becomes 0A.

(4) When the inductor current becomes 0A, the driver transistor is turned on again.

(5) If the output voltage is larger than setting voltage, the operations of (2) to (5) are repeated.

(6) When the output voltage becomes smaller than setting voltage, operation starts in PFM/fixed off-time PWM control.

Current Limit LEVEL in Start-up

0mA

GND

VOUT

ILX

VIN

GND

100% of setting voltage

XCL301 Datasheet(PDF) 9 Page - Torex Semiconductor