XC6401 데이터 시트보기 (PDF) - TOREX SEMICONDUCTOR

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XC6401

Dual LDO Regulators, Low ESR Cap. Compatible

TOREX SEMICONDUCTOR 

XC6401 Series

■OPERATIONAL EXPLANATION

＜Output Voltage Control＞

The voltage divided by resistors R1 & R2 is compared with the internal reference voltage by the error amplifier. The

P-channel MOSFETs, which are connected to the VOUT1 and VOUT2 pins, are then driven by the subsequent output

signal. The output voltages at the VOUT1 and VOUT2 pins are controlled and stabilized by a system of negative

feedback. The current limit circuit and short protect circuit operate in relation to the level of output current. Further, the

IC's internal circuitry can be shutdown via the EN pin's signal.

EN1

VIN

VSS

EN2

ON/OFF

Control

VR1

each

circuit

-

Error

Amp1

+

VR2

each

circuit

ON/OFF

Control

Voltage

Reference

-

Error

Amp2

+

Current

Limit

Current

Limit

VOUT1

R11

R12

VOUT2

R21

R22

＜Low ESR Capacitors＞

With the XC6401 series, a stable output voltage is achievable even if used with low ESR capacitors as a phase

compensation circuit is built-in. In order to ensure the effectiveness of the phase compensation, we suggest that output

capacitors (CL1, CL2) is connected as close as possible to the output pins (VOUT1 and VOUT2) and the VSS pin.

Please use an output capacitor with a capacitance value of at least 1μF. Also, please connect an input capacitor (CIN) of

1μF between the VIN pin and the VSS pin in order to ensure a stable power input.

＜Current Limiter, Short-Circuit Protection＞

The XC6401 series includes a combination of a fixed current limiter circuit & a foldback circuit which aid the operations of

the current limiter and circuit protection. 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, a current of about 30mA flows.

＜EN Pins＞

The IC's internal circuitry can be shutdown via the signal from the EN1 and EN2 pins with the XC6401 series. In

shutdown mode, output at the VOUT1 and VOUT2 pins will be pulled down to the VSS level via R11 & R12 and R21 & R22.

The operational logic of the IC's EN1 and EN2 pins are selectable (please refer to the selection guide). Note that as the

standard XC6401FF type's regulator 1 and 2 are both ' High Active/No Pull Down', operations will become unstable with

the EN1 or EN2 pins open. Although the EN1 and EN2 pins are equal to an inverter input with CMOS hysteresis, with

either the pull-up or pull-down options, the EN1 and EN2 pins input current will increase when the IC is in operation.

We suggest that you use this IC with either a VIN voltage or a VSS voltage input at the EN1 and EN2 pins. If this IC is

used with the correct specifications for the EN1 and EN2 pins, the operational 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.

■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 keep the resistance low between VIN and VSS wiring in particular.

3. Please wire the input capacitor (CIN) and the output capacitors (CL1, CL2) as close to the IC as possible.

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