LM339N

The LM339N from Texas Instruments is a quad differential comparator in a 14-pin DIP package. It contains four independent comparators with open-collector outputs, each capable of sinking up to 16mA. The device operates from a single 2V to 36V supply with input common-mode range that includes ground. Its open-collector output configuration allows wired-OR connections and direct interface with TTL and CMOS logic families. The LM339 is one of the most widely used comparators in industrial and consumer electronics.

Each comparator in the LM339N consists of a differential input stage and an open-collector output stage. The comparator continuously monitors the voltage difference between its inverting and non-inverting inputs. When the non-inverting input voltage exceeds the inverting input, the output transistor turns off (open circuit). When the inverting input exceeds the non-inverting input, the output transistor turns on, sinking current to ground. The open-collector output requires an external pull-up resistor to establish the high logic level. This configuration allows multiple outputs to be connected together for wired-OR logic.

• Voltage level detection and battery monitoring
• Zero-crossing detection in AC signal processing
• Window comparators for alarm and trip circuits
• Oscillator and timing waveform generators
• Logic level translation between different voltage domains