LM393P

The LM393P is a dual differential voltage comparator — basically, two comparators in one chip. It’s designed to compare two voltages and switch its output depending on which input is higher. It’s widely used in signal threshold detection, zero-crossing detectors, voltage monitoring, level detection, and more 🛠️.

🧠 Key Features

Dual comparators in one IC (two independent channels).

Wide supply voltage: 2 V to ~36 V (single supply) or ±1 V to ±18 V (dual supply).

Open-collector outputs — needs a pull-up resistor for high state.

Low supply current: roughly ~0.4 mA total (independent of supply voltage).

Input common-mode includes ground — so it can sense near 0 V even in single-supply applications.

TTL/CMOS compatible outputs with the right pull-up.

Reliable performance across many general-purpose applications.

🧾 Electrical Specifications
Parameter Typical / Max Value Notes
Supply Voltage (Vs) 2 V to ~36 V Single or dual supplies.
Operating Current ~0.4 mA total Tiny power draw.
Input Offset Voltage (V_OS) ~5 mV max Small error between comparators.
Input Bias Current ~25 nA typical Low input leakage.
Output Current ~20 mA per comparator With external pull-up.
Response Time / Prop Delay ~300 ns – 1.3 µs Fast enough for many control tasks.
Output Type Open-collector Needs external pull-up resistor.
Package 8-pin PDIP Through-hole mounting.
Temp Range 0 °C to 70 °C Commercial grade.
🔌 How It Works (at a glance)

Each comparator inside the IC compares IN+ vs IN-.

When IN+ > IN-, the open-collector output transistor turns off (output goes high via pull-up).

When IN+ < IN-, the transistor turns on (output pulls low to near ground).

Because outputs are open-collector, you add a pull-up resistor (e.g., 4.7 kΩ) to your logic voltage rail.

💡 Tip: This open-collector nature lets you wire multiple comparators together in a “wired-AND” configuration if needed.

🛠️ Typical Uses

✔ Threshold voltage detection
✔ Zero-crossing circuits
✔ Battery level monitoring
✔ Analog-to-digital level conversion
✔ Motor speed control
✔ Window comparators
✔ Oscillators and pulse generators