XC6416 Datasheet, PDF (10/30 Pages) Torex Semiconductor – Dual LDO Voltage Regulator with “GreenOperation”

XC6416 Series
˙OPERATIONAL DESCRIPTION (Continued)
<CL Auto-Discharge Function>
XC6416B/D/F/H series can quickly discharge the electric charge at the output capacitor (CL), when a low signal to the EN 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). The C_L discharge resistance is set to 550Њ when V_IN is 6.0V (TYP.) and V_OUT is 4.0V
(TYP.). Moreover, discharge time of the output capacitor (CL) is set by the C_L 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 ( V / VOUT )
V : Output voltage after discharge, VOUT(E) : Output voltage, t: Discharge time,
Н: CL auto-discharge resistance RʷOutput capacitor (CL) value C
C_L high-speed discharge function can be set by each regulator.
<Current Limiter, Short-Circuit Protection>
The XC6416 series includes a fold-back circuit, which aid the operations of the current limiter and circuit protection. When
the load current reaches the current limit level, the fold-back circuit operates and output voltage drops. As a result of this drop
in output voltage, output current also decreases. When the output pin is shorted, a current of about 20mA (TYP.) flows.
<EN Pin>
The IC's internal circuitry can be shutdown via the signal from the EN pin with the XC6416 series. In shutdown mode,
output at the VOUT pin will be pulled down to the VSS level via Rx1 & Rx2. However, as for the XC6416B/D/F/H series, the
CL auto-discharge resistor is connected in parallel to Rx1 and Rx2 while the power supply is applied to the VIN pin.
Therefore, time until the VOUT pin reaches the VSS level becomes short. The output voltage becomes unstable, when the
EN pin is open. If this IC is used with the correct output voltage for the EN pin, the logic is fixed and the IC will operate
normally. However, supply current may increase as a result of through current in the IC's internal circuitry when medium
voltage is input.
˙NOTES ON USE
1. Please use this IC within the stated absolute maximum ratings. The IC is liable to malfunction should the ratings be
exceeded.
2. Where wiring impedance is high, operations may become unstable due to noise and/or phase lag depending on output
current. Please wire the input capacitor (CIN) and the output capacitor (CL) as close to the IC as possible.
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