Reference voltage (Vref)

The Vref output is linked to the input; if either IN1 or IN2 is high, the reference voltage is output.

Output current limiter

The schematic for the output current limiter is shown below.

amplifier.

negative (–) side of the same amplifier, and the differential amplifier functions and the output transistors are driven so that these

inputs become equal.

The set current value in this instance is determined by the following equation:

Set current detector

(1) When DEL = high

greater than the input voltage on the positive (+) side. As a result, the drive current increases and the output PNP transistors

reach the saturation state. If this state is detected, the detection signal is sent to the set current detector, and the RD output

goes high.

goes low.

(2) When DEL = low

Because the operation of the current setting amplifier is cancelled when a low signal is input to the DEL pin, the output PNP

transistors reach the saturation state and the RD output goes high, just as in the case described above.

The following table summarizes the states described above.

DEL

OUT

RD

H

limit

L

Non-limit (saturated)

H

L

Saturated

H

Output Current Limiter and Set Current Detector Block Diagram

Set current

detector

LB1843V

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