LM393

The LM393 is a dual voltage comparator integrated circuit widely used in electronic circuits. It contains two independent differential comparators and is designed to compare two input voltages and produce a digital-like output. The outputs are open-collector NPN transistors, which means they sink current and require external pull-up resistors to generate a logic-high level. Because of the open-collector arrangement, the two channels can be used with different pull-up voltages and can be wired to different logic levels.

The device operates from a single supply in the range of about 2 to 36 volts, though the input common-mode range typically includes ground and extends only up to roughly Vcc minus 1.5 volts. This affects how close the inputs can get to the supply rails. The LM393 is valued for low input bias currents and low offset voltages (a few millivolts typical), with propagation delays in the microsecond region depending on supply, temperature, and load. Each channel can sink up to about 16 mA.

Applications for the LM393 include threshold and window detectors, zero-cross detectors, battery and power monitoring, level shifting, and simple PWM or control circuits where a fast, low-power comparator is suitable. It is not a high-precision amplifier and does not include internal hysteresis, though positive feedback can be added externally if hysteresis is required.

Packaging commonly includes DIP-8 and small-outline SO-8 variants. The LM393 has become a staple in analog and mixed-signal design due to its simplicity, availability, and low cost.