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OPERATIONAL EXPLANATION

＜

Output Voltage Control＞

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

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.

＜

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

＜

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

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.

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.

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

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NOTES ON USE

VR1

each

circuit

ON/OFF

Control

Error

Amp1

-

+

Voltage

Reference

ON/OFF

Control

Current

Limit

VR2

each

circuit

Error

Amp2

-

+

Current

Limit

EN1

EN2

R11

R12

R21

R22