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Dual voltage comparator

LM393 Internal Circuitry

Explore the internal circuitry and functional stages of LM393.

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Inside LM393

Two differential channels with independent open-collector outputs.

Two comparator channels share supply pins. Each differential input drives an output transistor whose emitter returns to ground and collector is the output pin. External pull-ups create HIGH levels.
Functional architecture; the pull-up resistors are external to the IC.

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Select a stage to see its role and connections

Differential input

Compare the two input voltages while respecting their valid range.

Open-collector switch

The collector is exposed at OUT. A LOW state sinks current; an off transistor releases the node.

Shared supply

Both channels use VCC pin 8 and GND pin 4, but each has its own inputs and output.

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