XC6207_1 Datasheet, PDF (11/33 Pages) Torex Semiconductor – High Speed "Green Operation" LDO Voltage Regulators

XC6207
Series
˙OPERATIONAL EXPLANATION (Continued)
<CL Auto-Discharge Function>
XC6207B 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 VOUT pin
and the VSS pin (cf. BLOCK DIAGRAM). In this state, the application is protected from a glitch operation caused by the
electric charge at the output capacitor (CL). The CL auto- discharge resistance at this time depends on the input
voltage. Moreover, 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 Н(Н=C x R), the output voltage after discharge via the N channel transistor is calculated by the following
formulas.
V = VOUT x e ^–t/Н, or t=НIn (VOUT / V)
( V : Output voltage after discharge, VOUT(E): Output voltage, t: Discharge time,
Н: CL auto-discharge resistance RʷOutput capacitor (CL) value C)
Ta=25^OC
INPUT VOLTAGE CL AUTO-DISCHARGE RESISTANCE
2.0V
750Њ (TYP.)
3.0V
550Њ (TYP.)
4.0V
500Њ (TYP.)
5.0V
480Њ (TYP.)
6.0V
470Њ (TYP.)
(ex.) When input voltage: 4.0V, CL auto-discharge resistance: 500Њ (TYP.); output capacitor (CL): 10ЖF, VOUT:3.0V,
CE voltage=Changing from 4.0V to 0V (The CE pin L level signal)
1Н(500Жs) after CE OFF signal is inputted, VOUT(E) becomes: 3.0Vʷ0.368 = approx. 1.104V
2Н(1000Жs) after CE OFF signal is inputted, VOUT(E) becomes: 3.0Vʷ0.135 = approx. 0.405V
3Н(1500Жs) after CE OFF signal is inputted, VOUT(E) becomes: 3.0Vʷ0.050 = approx. 0.150V
4Н(2000Жs) after CE OFF signal is inputted, VOUT(E) becomes: 3.0Vʷ0.018 = approx. 0.055V
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