LM393P - Dual Comparator, 2V-36V, Open-Collector, 8-PDIP | Texas Instruments
MPN: LM393P ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.45 | $0.45 |
| 10 | $0.39 | $3.90 |
| 100 | $0.31 | $31.00 |
| 500 | $0.24 | $120.00 |
| 1,000 | $0.18 | $180.00 |
LM393P Overview
A voltage comparator is a fundamental analog building block that compares two input voltages and produces a digital logic-level output indicating which input is larger. Comparators belong to the broader category of analog comparators -> signal conditioning ICs -> amplifiers and comparators -> analog ICs -> semiconductors. The LM393 family is one of the industry's longest-standing and most widely second-sourced comparator designs, making the LM393P a staple in through-hole commercial, industrial, and educational designs. Open-collector outputs allow the user to define the output high level via an external pull-up resistor to any reference voltage, including a logic level different from VCC, enabling level shifting and OR-wired multi-comparator topologies.
Key features include a maximum input offset voltage of ±5 mV, an input bias current of 25 nA typical, a quiescent supply current of 0.4 mA typical (independent of supply voltage), and an open-collector output capable of sinking up to 16 mA. The wide supply range (2V to 36V single supply) and low input bias current make the LM393P well suited to direct interfacing with sensors, op-amp outputs, and TTL/CMOS logic families without additional level translation.
Each comparator channel consists of a low-offset differential input stage followed by an open-collector NPN output transistor. The output transistor is OFF when the non-inverting (+) input is at lower potential than the inverting (-) input, and saturates to pull the output LOW when + exceeds -. Designers commonly add an external pull-up resistor (typically 10 kohm to VCC) to establish the HIGH level, which is critical because an open-collector output cannot actively drive HIGH.
Typical applications include zero-crossing detectors, over/under-voltage monitors, battery low-detection circuits, window comparators, oscillators, Schmitt triggers, and sensor signal conditioning for industrial, automotive, and consumer designs. The LM393P's through-hole PDIP package supports breadboard prototyping, educational labs, and legacy through-hole PCB designs where surface-mount variants (LM393D, LM393DR) are unsuitable.
When designing with the LM393P, place a 0.1 uF bypass capacitor as close as possible to the VCC pin and ensure the pull-up resistor value is sized against the desired output rise time and load capacitance. Avoid driving the output above the maximum collector-emitter voltage of 36V and respect the absolute maximum input common-mode range of -0.3V to VCC to prevent input stage damage.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet, with verified values drawn from TI product page, DigiKey catalog, and the LM393B/LM2903B datasheet family specification table.
Drop-in alternatives for LM393P — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with LM393P (same form factor and footprint) — differing in Comparator Type, Output Type, Package, RoHS Status, Number of Comparators.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
LM393N
✅ Drop-In✓ In Stock
$0.18 / Unit
View Datasheet →LM2903P
✅ Drop-In📋 Reference alternative (not in catalog)
LM393AP
✅ Drop-In📋 Reference alternative (not in catalog)
LM358P
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
LM393P
✅ Drop-In✓ In Stock
$0.18 / Unit
View Datasheet →LM2903N
✅ Drop-In✓ In Stock
$0.27 / Unit
View Datasheet →LM393P Maximum Ratings & Electrical Characteristics
| Comparator Type | Differential (general purpose) |
| Number of Comparators | 2 (dual) |
| Output Type | Open-Collector |
| Supply Voltage (Single) | 2 V to 36 V |
| Supply Voltage (Dual) | ±1 V to ±18 V |
| Input Offset Voltage (Max) | ±5 mV |
| Input Bias Current (Typical) | 25 nA |
| Quiescent Current (Typical) | 0.4 mA |
| Response Time | 1.3 us (typical) |
| Propagation Delay | 300 ns |
| Output Sink Current (Max) | 16 mA |
| Operating Temperature | 0 C to +70 C |
| Package | 8-PDIP (P) through-hole |
| Mounting Type | Through-Hole |
| RoHS Status | Compliant |
LM393P Pin Configuration
| Pin 1 | OUTPUT A — Comparator A open-collector output |
| Pin 2 | INVERTING INPUT A (INA-) — Comparator A inverting input |
| Pin 3 | NON-INVERTING INPUT A (INA+) — Comparator A non-inverting input |
| Pin 4 | VCC — Positive supply voltage |
| Pin 5 | NON-INVERTING INPUT B (INB+) — Comparator B non-inverting input |
| Pin 6 | INVERTING INPUT B (INB-) — Comparator B inverting input |
| Pin 7 | OUTPUT B — Comparator B open-collector output |
| Pin 8 | GND — Ground |
Typical Applications
LM393P is suitable for 6 applications: Zero-Crossing Detector, Battery Low-Voltage Detector, Over/Under-Voltage Window Comparator, RC Oscillator / Square-Wave Generator, Sensor Signal Conditioning (Light/Temperature), Schmitt Trigger / Hysteresis Comparator.
Zero-Crossing Detector
The LM393P is well suited to AC mains zero-crossing detection where its open-collector output drives a microcontroller interrupt input directly. With a 2V-36V supply range, the chip can be powered from a rectified 5V or 12V rail and accept the attenuated AC waveform on its non-inverting input via a resistor divider. The 1.3 us response time is adequate for 50/60 Hz mains detection, and the wide common-mode input range (0V to VCC-1.5V) allows direct coupling to the divided AC waveform without DC offsetting. Place a 10 kohm pull-up on the open-collector output tied to the MCU VCC to level-shift the logic-high reference independently of VCC.
Recommended
Battery Low-Voltage Detector
The LM393P excels at single-cell or multi-cell battery low-voltage warning circuits because its wide 2V-36V supply accommodates everything from a 2-cell alkaline pack up to a 24V industrial battery. Connect a resistor divider from the battery to the inverting input and a stable reference (e.g., a TL431 or bandgap) to the non-inverting input; when Vbat falls below the threshold, the open-collector output pulls LOW and can sink an LED or enable a low-power warning transistor. The chip's 0.4 mA quiescent current minimizes drain on the battery itself, critical for long shelf-life applications. The 8-PDIP package supports through-hole battery-pack PCBAs where surface-mount parts are impractical.
Recommended
Over/Under-Voltage Window Comparator
Two LM393P channels together form a window comparator that flags when a monitored rail falls outside an acceptable band, ideal for power-supply rails in industrial 24V or automotive 12V systems. One channel compares Vrail against an upper threshold; the second compares against a lower threshold; their open-collector outputs can be wire-ANDed to a single MCU alarm pin because the LM393P outputs are open-collector (multiple chips can share one pull-up). The 36V absolute maximum input common-mode and the 2V minimum supply let the LM393P monitor 5V, 12V, 15V, and 24V rails from the same chip without divider re-engineering. Add 100 kohm positive-feedback resistors around each comparator to create hysteresis of 50-200 mV if the monitored rail is noisy.
Recommended
RC Oscillator / Square-Wave Generator
Two LM393P comparators plus an RC network form a low-cost square-wave oscillator in the 1 Hz to 100 kHz range, useful for clock generation, blinkers, and tone generators. With a single 5V supply, the comparator thresholds are set by the ratio of the timing resistor to the feedback network, and the duty cycle is adjustable via asymmetric resistor selection. The 300 ns propagation delay is small relative to the RC period and only contributes a minor timing error above 1 MHz. The dual-channel package lets one chip produce quadrature or complementary outputs directly, eliminating the need for a second IC.
Recommended
Sensor Signal Conditioning (Light/Temperature)
The LM393P is the canonical comparator for photodiode, phototransistor, and thermistor-based sensor interfaces because the open-collector output can drive an MCU interrupt or LED directly without a buffering transistor. With a single 5V rail and a 10 kohm pull-up, the chip converts a high-impedance analog sensor signal into a clean CMOS logic-level output, with adjustable threshold set by a divider on the reference input. The 25 nA input bias current minimizes loading on high-impedance sensors, and the 0C to +70C commercial temperature range covers indoor IoT, appliance, and consumer-product sensor designs.
Recommended
Schmitt Trigger / Hysteresis Comparator
Adding two positive-feedback resistors around one LM393P comparator creates a non-inverting Schmitt trigger with adjustable hysteresis from a few millivolts to several hundred millivolts, ideal for debouncing mechanical switches or cleaning up noisy sensor edges. The hysteresis band is set by the ratio of the feedback resistor to the input resistor, and the wide supply range (2V-36V) lets one chip work at 3.3V for digital logic or at 24V for industrial debouncing. Compared to a logic-gate Schmitt trigger (e.g., 74HC14), the LM393P has analog threshold control and lower output impedance in the LOW state (16 mA sink).
Recommended
Recommended Products Summary
Engineering reference data for LM393P — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LM393N | LM2903P | LM393AP |
|---|---|---|---|---|
| Package | 8-PDIP (P) | 8-PDIP - same | 8-PDIP - same | 8-PDIP - same |
| Brand | Texas Instruments | Texas Instruments (same brand) | Texas Instruments (same brand) | STMicroelectronics (cross-brand) |
| Number of Comparators | 2 | 2 | 2 | 2 |
| Supply Voltage (Single) | 2V to 36V | 2V to 36V | 2V to 36V | 2V to 36V |
| Input Offset Voltage (Max) | ±5 mV | ±5 mV | ±5 mV | ±1 mV |
| Quiescent Current (Typical) | 0.4 mA | 0.4 mA | 0.4 mA | 0.4 mA |
| Operating Temperature | 0C to +70C | 0C to +70C | -40C to +125C | 0C to +70C |
| Output Type | Open-Collector | Open-Collector | Open-Collector | Open-Collector |
| Output Sink Current (Max) | 16 mA | 16 mA | 16 mA | 16 mA |
| Unit Price (qty 1) | $0.45 | $0.42 - $0.50 | $0.50 - $0.60 | $0.65 - $0.80 |
Key Differentiators
- Through-hole 8-PDIP package - breadboard and legacy PCB compatible (vs LM393D)
- Commercial-grade 0C to +70C temperature range (vs LM2903P)
- Standard ±5 mV input offset (vs ±1 mV LM393AP) (vs LM393AP)
- Dual independent comparators in a single 8-pin IC (vs LM311 single comparator)
Design Notes
Estimated: Quiescent current of 0.4 mA plus up to 16 mA output sink load gives a typical supply current of 0.4-16.4 mA per LM393P. Use a 100 mA LDO or supply rail rated well above this; do not derive VCC from a high-impedance source. Place a 0.1 uF ceramic bypass capacitor on the VCC pin (pin 4) with trace length under 5 mm to ground (pin 8) to suppress switching noise; add a 10 uF bulk capacitor near the supply if the rail is shared with motors or relays.
The open-collector output CANNOT drive HIGH on its own - omitting the external pull-up resistor will leave the output floating HIGH at undefined voltage, causing spurious MCU interrupts and unreliable logic-level detection. Use a pull-up between 1 kohm and 100 kohm tied to a logic-level rail up to 36V. Also: the input common-mode range only extends from 0V to VCC-1.5V; do not apply signals below GND or above VCC, as this forward-biases the ESD diodes and may damage the part.
For breadboard and through-hole layouts using the LM393P 8-PDIP, keep input traces short to reduce noise pickup, especially for high-impedance sensor inputs. Place the 0.1 uF decoupling cap on pin 4 with the ground side returning directly to pin 8 to minimize ground bounce. If designing a precision comparator circuit with sub-millivolt threshold accuracy, use a guard ring around the high-impedance input node driven at the same potential to eliminate leakage currents from the PCB surface.
Estimated: input bias current of 25 nA flowing through a 1 Mohm source impedance creates a 25 mV error, comparable to the 5 mV offset voltage. If the source impedance exceeds 100 kohm, switch to a CMOS comparator (LM393LV, LMV331) with sub-nA bias current or buffer the LM393P input with an op-amp follower. For switching at higher frequencies, the 300 ns propagation delay contributes an offset of 300 ns * dV/dt on the input; mitigate this by choosing faster parts (TLV3201, LM393LV) above 100 kHz.
Compliance Information
Commercial-grade plastic PDIP, not AEC-Q100 qualified; choose LM2903P for automotive or industrial-temperature applications. RoHS and lead-free per TI product page; REACH compliance status per DigiKey listing as of 2026-10-21.
