XC9237C2ACEL datasheet(11/28 Pages) TOREX

11 / 28 page

11/28

XC9235/XC9236/XC9237

Series

Output Voltage Dischage Characteristics

Rdischg

（）

= 300Ω TYP

Discharge Time t (ms)

100

20304050

607080

100

CL=10uF

CL=20uF

CL=50uF

■OPERATIONAL DESCRIPTION (Continued)

＜CL High Speed Discharge＞

XC9235B(C)/ XC9236B(C)/ XC9237B(C) series can quickly discharge the electric charge at the output capacitor (CL) when

a low signal to the CE pin which enables a whole IC circuit put into OFF state, is inputted via the N-channel transistor

located between the LX pin and the VSS pin. When the IC is disabled, electric charge at the output capacitor (CL) is quickly

discharged so that it may avoid application malfunction. Discharge time of the output capacitor (CL) is set by the CL

auto-discharge resistance (R) and the output capacitor (CL). By setting time constant of a CL auto-discharge resistance

value [R] and an output capacitor value (CL) as τ(τ=C x R), discharge time of the output voltage after discharge via the N

channel transistor is calculated by the following formulas.

V = VOUT(E) x e

–t/τ, or t=τln (VOUT(E) / V)

V : Output voltage after discharge

VOUT(E) : Output voltage

t: Discharge time,

τ: C x R

C= Capacitance of Output capacitor (CL)

R= CL auto-discharge resistance

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