LM393P: Dual Differential Comparator for Voltage Detection

ElecSuppliers Part Number ComparisonAug 21, 2026

The LM393P is a dual differential voltage comparator designed for detecting the relationship between two analog input voltages. It contains two independent comparator circuits in a single package, allowing one device to perform multiple threshold-detection functions.

The LM393 family is widely used in analog and mixed-signal circuits where an analog voltage needs to be converted into a digital-style high or low signal.

What Is the LM393P?

The LM393P contains two independent voltage comparators.

Each comparator compares the voltage applied to its non-inverting input with the voltage applied to its inverting input.

When the relationship between the two input voltages changes, the comparator output changes state according to the device's operating characteristics.

This makes the LM393P useful for applications such as voltage monitoring, level detection, zero-crossing detection and simple analog-to-digital threshold circuits.

LM393P Dual Comparator Configuration

Two comparator channels are integrated into the LM393P.

The channels operate independently, so they can monitor two different signals or be combined within a larger analog control circuit.

For example, one comparator can monitor a supply voltage while the second comparator monitors a sensor output.

Using a dual comparator instead of two separate ICs can reduce PCB component count and simplify the overall circuit.

LM393P Voltage Detection

One of the most common uses for the LM393P is voltage threshold detection.

A resistor divider can generate a reference voltage, while the monitored signal is connected to the other comparator input.

When the monitored voltage crosses the reference level, the comparator output changes state.

This simple architecture can be used to detect undervoltage, overvoltage or a particular sensor threshold.

The accuracy of the final detection circuit depends not only on the comparator but also on the reference source and resistor tolerances.

LM393P Open-Collector Output

The LM393P uses an open-collector output structure.

Unlike a conventional push-pull logic output, an external pull-up resistor is normally required to produce a high logic level.

This configuration provides useful flexibility because the output can interface with different logic supply voltages within the applicable electrical limits.

The open-collector output can also be useful when multiple signals need to be combined using wired logic.

The pull-up resistor value should be selected according to the required switching speed, load current and logic-level requirements.

LM393P Sensor Interface

The LM393P can be used to convert an analog sensor signal into a threshold-based digital signal.

For example, a light sensor, temperature-dependent voltage or other analog signal can be compared with a fixed reference.

Instead of requiring the MCU to continuously sample the analog signal, the comparator can generate a logic transition when the signal crosses the selected threshold.

This can reduce software processing requirements in simple detection applications.

LM393P Zero-Crossing Detection

The comparator architecture can also be used for zero-crossing or polarity-detection circuits when the input signal and supply configuration are appropriate.

The comparator determines which input is at the higher voltage and changes its output accordingly.

For AC or bipolar signals, the surrounding circuit must be designed carefully because the allowable input common-mode range and supply configuration determine which signal conditions can be safely applied.

LM393P Threshold Adjustment

The detection threshold can be fixed or adjustable.

A resistor divider can establish a fixed reference voltage, while a potentiometer can allow the threshold to be adjusted during development or operation.

For products where the threshold must remain stable over temperature and supply variation, a more accurate reference circuit may be preferable.

The comparator itself should be considered as one part of the complete threshold-detection system.

LM393P Response and Switching Speed

The LM393P is intended for general-purpose comparator applications rather than extremely high-speed signal processing.

The propagation delay depends on operating conditions and the amount of overdrive applied to the inputs.

When the comparator is used at higher frequencies, designers should evaluate propagation delay, output pull-up resistance and load capacitance together.

For simple voltage monitoring and sensor threshold applications, these factors are usually easier to accommodate.

LM393P Single-Supply Applications

The LM393P can be used in single-supply circuits, which makes it convenient for many embedded systems.

A single positive supply can power the comparator while the monitored signals remain within the appropriate input range.

This is particularly useful in battery-powered equipment, embedded controllers and low-voltage monitoring circuits.

The actual input voltage range should always be checked against the supply voltage and the required operating conditions.

LM393P Applications

The LM393P can be used in a wide variety of voltage-detection and control circuits.

Typical applications include battery monitoring, overvoltage detection, undervoltage detection, level sensing, zero-crossing detection, oscillator circuits, sensor interfaces and simple control systems.

It can also be used as a threshold detector between an analog circuit and a digital microcontroller input.

LM393P Package

The LM393P is available in a through-hole package configuration.

This makes it convenient for prototypes, development boards, educational electronics and designs where through-hole components are preferred.

For surface-mount production, other LM393 package variants may be more suitable.

When replacing the LM393P, the complete Part Number and package type should therefore be checked before selecting another LM393 variant.

LM393P PCB Design Considerations

Comparator circuits can be sensitive to noise when the input signals are close to the switching threshold.

The reference voltage and signal traces should be routed carefully and kept away from high-current switching nodes where possible.

A suitable bypass capacitor should also be placed close to the comparator supply pins.

If the monitored signal contains significant noise, an RC filter or hysteresis circuit may be required to prevent unwanted output switching around the threshold.

Choosing the LM393P

The LM393P is a practical choice when a design requires two independent voltage comparators in a general-purpose analog circuit.

Its dual-channel configuration and open-collector outputs make it useful for voltage monitoring, sensor threshold detection and interfaces between analog signals and digital controllers.

Before selecting the LM393P, engineers should evaluate input voltage range, reference accuracy, propagation delay, output pull-up requirements, supply voltage and package type.

For procurement and BOM management, using the complete LM393P Part Number helps distinguish the required package configuration from other LM393 variants.