XC6217_2 Datasheet, PDF(13/33 Page) Torex Semiconductor – High Speed "Green Operation" LDO Voltage Regulators

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XC6217_2 Datasheet, PDF (13/33 Pages) Torex Semiconductor – High Speed "Green Operation" LDO Voltage Regulators

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XC6217

Series

XC6217B/D 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). The CL auto-discharge resistance value is fixed to 780Î©(VIN=6.0V, VOUT=4.0V at

typical). The 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 [RDCHG] and an output capacitor value

(CL) as Ï(Ï=C x RDCHG), the output voltage after discharge via the N channel transistor is calculated by the following

formulas.

V = VOUT(E) x e ât/Ï, or t=ÏIn ( V / VOUT(E) )

( V : Output voltage after discharge, VOUT(E) : Output voltage, t: Discharge time,

Ï: CL auto-discharge resistance RDCHGÃOutput capacitor (CL) value C)

The XC6217 seriesâ foldback circuit operates as an output current limiter and a short protection of the output pin. When

the load current reaches the current limit level, the fixed current limiter circuit operates and output voltage drops. As a

result of this drop in output voltage, the foldback circuit operates, output voltage drops further and output current

decreases. When the output pin is shorted to the VSS level, a current of about 30mA flows.

The IC's internal circuitry can be shutdown via the signal from the CE pin with the XC6217 series. In shutdown mode,

output at the VOUT pin will be pulled down to the VSS level via R1 & R2. However, as for the XC6217B/D series, the CL

auto-discharge resistor is connected in parallel to R1 and R2 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

CE pin is open. If this IC is used with the correct output voltage for the CE 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.

â 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 strengthen VIN and VSS wiring in particular.

3. Please wire the input capacitor (CIN) and the output capacitor (CL) as close to the IC as possible.

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