Summary
The LM393 Voltage Comparator is a dual differential IC designed for single or dual supply operation (2 V to 36 V / ±1 V to ±18 V), offering open-collector outputs that directly interface with TTL, CMOS, and MOS logic families. Texas Instruments originally introduced this device, and dozens of manufacturers now second-source it. Consequently, it is qualified to JEDEC JESD48 package standards and tested per IEC 60068 environmental procedures, making it a reliable staple in global bill-of-materials. With billions of units shipped annually, the LM393 underpins voltage sensing in industrial control systems, battery-powered consumer electronics, and automotive sub-systems where engineers need a fast, low-power comparator.
Key Takeaways
▸Supply range: 2 V–36 V single supply or ±1 V to ±18 V split supply — works across 3.3 V, 5 V, 12 V, and 24 V systems.
▸Open-collector output directly interfaces with TTL, CMOS, and MOS logic without level-shifting buffers.
▸Typical response time: 1.3 µs with 5 mV overdrive — adequate for signals into the hundreds of kilohertz.
▸Available in DIP-8, SOP-8, TSSOP-8, and SOT-23-6; commercial, industrial (−40 °C to +125 °C), and AEC-Q100 automotive grades.
▸Ultra-low supply current of 0.4 mA (both channels) — ideal for battery-powered applications.
▸Stocked by 30+ manufacturers at LCSC from 1 piece, from USD 0.02–0.08 per unit.
What Is the LM393 Voltage Comparator?
The LM393 Voltage Comparator (also marketed as the LM393A, TS393, and KA393 depending on the manufacturer) is a dual independent voltage comparator in a standard 8-pin package. Each comparator section accepts two differential input voltages — non-inverting (IN+) and inverting (IN−) — and drives a single open-collector NPN transistor output. When IN+ exceeds IN−, the output transistor switches off and the output pulls high through an external pull-up resistor. When IN− exceeds IN+, the transistor conducts and pulls the output low. This fundamental operating principle enables the device to act as a precision threshold detector, zero-crossing detector, or analog-to-digital interface with no additional active components.
The LM393 Voltage Comparator operates from a single supply rail of 2 V to 36 V, or from a split supply of +±1 V to ±18 V. As a result, designers gain flexibility across 3.3 V microcontroller, 5 V TTL, 12 V industrial, and 24 V relay-driving environments. The input common-mode voltage range extends from ground to approximately VCC − 2 V, permitting inputs close to the negative rail — an important attribute in single-supply designs. Furthermore, the typical response time of 1.3 µs (measured with a 5 mV overdrive) enables the device to track signals into the hundreds of kilohertz, which is adequate for the vast majority of industrial and consumer sensing applications.
Physically, the LM393 Voltage Comparator is available in DIP-8, SOP-8 (SOIC-8), TSSOP-8, and SOT-23-6 packages, all conforming to JEDEC JESD48 mechanical outlines. The operating temperature range covers the commercial grade (0 °C to +70 °C) and the industrial grade (−40 °C to +125 °C), and automotive-grade (AEC-Q100 Grade 1) variants are available from several suppliers. Supply current is typically 0.4 mA per comparator, making the LM393 one of the most power-efficient general-purpose comparators in its class.
Key Features & Advantages of the LM393 Voltage Comparator
Wide Supply Voltage Range (2 V – 36 V)
The LM393 operates from 2 V up to 36 V, making it architecture-agnostic. In practice, a single part number works in 3.3 V MCU reference designs, 5 V legacy boards, 12 V automotive accessories, and 24 V industrial PLCs. This breadth eliminates the need for multiple comparator variants across a product family, reducing component diversity and simplifying supply-chain management. Moreover, the wide headroom provides tolerance against transient over-voltage events common in motor-drive and relay environments.
Open-Collector Output Architecture
Unlike voltage-output comparators such as the LM311 with its emitter-follower output, the LM393 Voltage Comparator’s open-collector stage enables wire-AND logic. Multiple comparator outputs share a single pull-up resistor to implement an OR-of-comparisons function without additional gates. This directly simplifies over-current protection circuits where any one of several sensors must trip an alarm. In addition, the open-collector topology lets the designer set the output logic level independently of VCC. For example, a 3.3 V logic output is straightforward on a 12 V supply board by connecting the pull-up to a 3.3 V rail.
Low Input Offset Voltage (≤ 5 mV Typical)
Input offset voltage (VOS) is the residual differential voltage at the inputs when the output changes state under zero applied signal. The LM393 specifies a maximum VOS of 5 mV across the full commercial temperature range, so threshold levels remain predictable. In battery fuel-gauge applications where the voltage window between empty and full is as narrow as 200 mV, a 5 mV offset represents only 2.5% error — well within acceptable limits for most first-order designs without external trimming.
TTL/CMOS/MOS Logic Compatibility
The output stage sinks a minimum of 6 mA while maintaining VOL ≤ 400 mV, satisfying the VILIN specification of standard TTL and LVTTL gates. Simultaneously, the high-impedance open-collector output, when pulled up through a resistor to any logic supply between 3.3 V and 5 V, meets the VOH requirements of CMOS and MOS inputs. Consequently, the LM393 Voltage Comparator sits at the analog-digital boundary in mixed-signal boards without level-shifting buffers — a meaningful saving in PCB area and BOM cost.
Dual Independent Channels in a Single Package
Integrating two independent comparators into one 8-pin package halves the footprint versus using two single-comparator devices. Furthermore, sharing power and ground pins reduces routing complexity. Both channels are electrically isolated internally — cross-talk between channels is negligible — so one channel can detect over-voltage while the other detects under-voltage on the same rail. This approach implements a window comparator circuit without additional ICs, which is especially valuable in space-constrained IoT sensor nodes and wearable devices.
LM393 Voltage Comparator Technical Specifications
| Parameter | Symbol | Typical Range | Unit | Notes |
| Supply Voltage (Single) | VCC | 2 – 36 | V | Split supply ±1 V to ±18 V also supported |
| Input Common-Mode Range | VICM | GND to VCC − 2 | V | Allows inputs near negative rail in single-supply designs |
| Input Offset Voltage | VOS | ±2 (typ), ±5 (max) | mV | Measured at VCC = 5 V, TA = 25 °C |
| Response Time | tR | 1.3 (typ) | µs | 5 mV overdrive, 100 Ω pull-up to 5 V |
| Output Sink Current | ISINK | 6 (min), 16 (typ) | mA | VOL ≤ 400 mV at 6 mA |
| Supply Current (both channels) | ICC | 0.4 (typ), 1.0 (max) | mA | Per device; both channels active |
Overall, the LM393 Voltage Comparator achieves a compelling balance of speed (1.3 µs) and efficiency (0.4 mA typical) with a maximum input offset of 5 mV. As a result, it suits threshold-detection tasks across the full 2 V–36 V supply range without external bias circuitry.
LM393 Voltage Comparator Variants, Grades & Package Options
The LM393 Voltage Comparator is available in several temperature grades that match different procurement and reliability requirements. The standard commercial grade (suffix ‘N’ or no suffix) covers 0 °C to +70 °C and is the lowest-cost option for consumer and office equipment. The industrial grade (suffix ‘I’ or ‘M’) extends operation to −40 °C to +125 °C, which is mandatory for outdoor IoT gateways, HVAC controllers, and automotive accessory modules operating outside the cabin. Furthermore, AEC-Q100 Grade 1 variants (−40 °C to +125 °C with full PPAP documentation) are available from manufacturers such as Texas Instruments (LM393AQDBVRQ1) and Nexperia for tier-1 automotive supply chains.
Package selection strongly influences PCB density and assembly process. The through-hole DIP-8 variant remains popular for prototyping, hand-soldering, and industrial relay boards where mechanical robustness is prioritised over density. The SOP-8 (3.9 mm body width) balances solderability and footprint for mixed SMT boards, while the TSSOP-8 (3.0 mm wide, 0.65 mm pitch) suits high-density consumer PCBs. The SOT-23-6 is the preferred package for IoT nodes and wearables, offering a 2.9 mm × 1.6 mm footprint, roughly 70% smaller than the SOP-8, at a marginal cost premium. All packages comply with JEDEC JESD48 dimensional standards, ensuring interchangeability across qualified second sources.
From a procurement format perspective, the DIP-8 ships in bulk or tubes (typically 25–50 pieces per tube), while SOP-8, TSSOP-8, and SOT-23-6 variants are available in tape-and-reel (T&R) packaging on 7-inch or 13-inch reels conforming to EIA-481 standards — essential for automated pick-and-place assembly. MOQs at LCSC start at one piece for cut-tape and 3,000 pieces for full T&R reels. Engineers designing for production runs should confirm T&R availability early, as popular second-source variants such as WINSOK or JSMSEMI LM393 may carry shorter lead times than branded equivalents during supply constraints.
Common LM393 Voltage Comparator Application Scenarios
Battery Charge-Level Monitoring in Portable Devices
Environment: Li-ion or LiFePO4 battery management systems in handheld scanners, e-bikes, and medical monitoring devices.
Engineering Challenge: The system must detect when cell voltage crosses predefined thresholds — for example, 3.0 V for a low-battery warning or 4.2 V for a full-charge cut-off — and assert a logic signal to the host MCU without drawing significant quiescent current that would drain the battery during standby.
Solution: Each LM393 Voltage Comparator channel acts as a threshold detector. A precision resistor divider from the battery terminal sets the reference voltage on IN−, while IN+ connects directly to the battery node. When the battery voltage drops below the threshold, the comparator output transitions high via the pull-up resistor, triggering an interrupt on the MCU’s GPIO. Because typical ICC is only 0.4 mA total for both channels, the LM393 adds negligible load to a 2000 mAh cell and enables months of standby monitoring. Designers building portable power products should also consider proper battery charging circuit design to ensure stable threshold monitoring and safe charging behavior.
Zero-Crossing Detection for AC Phase Control
Environment: Triac or SCR phase-angle dimmer circuits in lighting control, induction cooktop power stages, and UPS inverters.
Engineering Challenge: Gate firing must synchronise to the AC mains zero-crossing point with microsecond precision. Any jitter or delay introduces phase error that causes visible flicker in lighting or audible noise in motor loads.
Solution: The mains waveform scales and level-shifts through an isolation transformer and resistor network to a 0 V–3 V sine wave centred on VCC/2. One LM393 Voltage Comparator channel compares this signal against VCC/2. The resulting 1.3 µs transition time generates a clean digital edge that triggers a microcontroller interrupt for precise firing-angle calculation. Moreover, the open-collector output, pulled up to the MCU’s 3.3 V rail, eliminates a level-shifter even though the comparator runs from a 5 V supply.
Over-Temperature Shutdown in Power Supplies
Environment: SMPS (switched-mode power supply) heatsink thermal monitoring in server PSUs, EV on-board chargers, and LED driver modules.
Engineering Challenge: An NTC thermistor’s resistance decreases exponentially with temperature. The circuit must trigger a fan ramp or shutdown signal when the heatsink exceeds 85 °C, while tolerating ambient temperatures up to 60 °C without false triggering.
Solution: An NTC thermistor forms the lower leg of a voltage divider to VCC; the midpoint voltage decreases as temperature rises. This midpoint feeds IN+ of the LM393 Voltage Comparator, while IN− connects to a fixed resistor divider calculated to match the NTC midpoint voltage at 85 °C. Crossing the threshold drives the open-collector output low, deactivating the SMPS via an enable pin. In addition, the second LM393 channel simultaneously monitors a second critical node such as a rectifier diode junction, implementing a full two-zone thermal protection system in a single 8-pin device.
PWM Duty-Cycle Generation from Analog Setpoint
Environment: DC motor speed controllers, LED dimmers, and solenoid valve drivers in industrial automation.
Engineering Challenge: A micro-power MCU must generate a variable duty-cycle PWM signal based on an analog setpoint voltage (for example, a potentiometer output) without consuming the MCU’s internal timer resources for the ramp generator.
Solution: A low-frequency triangle wave (typically 1–20 kHz, generated by an RC oscillator or DAC) feeds IN− of the LM393 Voltage Comparator, while the analog setpoint voltage feeds IN+. The comparator continuously compares these signals, producing a PWM output whose duty cycle is linearly proportional to the setpoint voltage relative to the triangle amplitude. For a typical 10 kHz triangle with 1 V peak-to-peak amplitude, a setpoint shift of 100 mV changes the duty cycle by approximately 10%. This technique off-loads PWM generation from the MCU entirely, freeing timer resources for control-loop execution.
Manufacturing & Procurement
More than thirty qualified suppliers worldwide manufacture the LM393 Voltage Comparator. These include Texas Instruments, STMicroelectronics, onsemi, Nexperia, Diodes Inc., WINSOK, and JSMSEMI. All manufacturers publish JEDEC-compatible datasheets. Finished goods undergo standard electrical end-of-line testing per IEC 60068-2. This covers temperature cycling, humidity, and vibration. AEC-Q100 Grade 1 variants require additional qualification steps. These include HTRB, HTSL, biased HAST, and ESD stress testing to JESD22-A114. Engineers targeting automotive or medical applications should request a PPAP document from the supplier. This confirms the specific lot is traceable to the AEC-Q100 flow.
Lead times for LM393DR (SOP-8) and LM393P (DIP-8) typically run 4–8 weeks from tier-1 distributors. Distributors such as LCSC maintain millions of units in bonded inventory. This includes both branded and authorised second-source parts. Stock availability can reduce lead times to immediate. During peak demand cycles, second-source variants from Chinese manufacturers often quote 2–4 weeks. Equivalent branded parts may quote 16–26 weeks during the same period. Procurement teams gain an important buffer without requiring any design changes.
MOQs at LCSC for cut-tape SOP-8 variants start at a single piece. Pricing ranges from approximately USD 0.03–0.08 per unit, depending on supplier tier. Full T&R reels of 3,000 pieces drop the per-unit cost to USD 0.02–0.04. This represents meaningful savings at volumes above 10,000 units annually. When sourcing, cross-reference the part number suffix against the datasheet. Confirm the temperature grade before placing volume orders. No suffix or ‘D’ indicates commercial grade; ‘I’ or ‘M’ indicates industrial. Mismatched temperature grades commonly cause field failures in equipment exposed to −20 °C conditions.
LM393 Voltage Comparator Type and Variant Comparison
| Type | Key Spec | Best For | Trade-off |
| LM393 (Commercial) | VOS ≤ 5 mV, 0 °C to +70 °C | Consumer electronics, indoor IoT sensors, hobbyist prototyping | Not suitable for automotive or outdoor industrial use; no AEC-Q100 |
| LM393I / LM393M (Industrial) | VOS ≤ 7 mV, −40 °C to +125 °C | Outdoor IoT gateways, HVAC controllers, industrial motor drives | Slightly higher offset voltage and cost premium (~15–30%) over commercial grade |
| LM393Q (Automotive AEC-Q100) | VOS ≤ 5 mV, −40 °C to +125 °C, PPAP available | Automotive body control, EV BMS pre-charge detection, ADAS power rails | Longest lead times, highest unit cost; requires PPAP from authorised source |
| LM2903 (Pin-Compatible Upgrade) | VOS ≤ 5 mV, wider input CMR, lower ICC | Drop-in upgrade where lower quiescent current or better offset is needed | Marginally higher cost; verify datasheet CMR and output sink spec before swap |
For new designs targeting the broadest supply-chain flexibility, specify the LM393DR (SOP-8, commercial) as the primary part and add the LM393IDR (industrial, SOP-8) as an approved alternative in the AVL. Both options are pin-compatible with identical footprints, and both are available from multiple second sources at LCSC. Reserve the AEC-Q100 LM393Q variant only where formal automotive qualification documentation is contractually required, as supply-chain constraints rarely justify the premium for non-automotive applications.
LM393 Voltage Comparator FAQ
How Do I Calculate the Hysteresis Resistor for a Stable Threshold?
Add hysteresis by connecting positive feedback from the open-collector output back to IN+. Use a pull-up resistor RP and a feedback resistor RF. When the output is high, feedback current raises IN+ above the set threshold. When the output is low, IN+ is pulled below it. The hysteresis voltage is approximately VHYS = (VPU × R1) / (RF + R1). Here, VPU is the pull-up voltage and R1 is the lower resistor of the IN+ divider. For a typical 5 V system with RP = 10 kΩ, R1 = 10 kΩ, and RF = 100 kΩ, VHYS ≈ 45 mV. This is sufficient to prevent chatter for signals with up to 30 mV of superimposed noise. Always verify that VHYS exceeds the peak-to-peak noise amplitude at the input node.
What Qualification Standards Apply, and Are Automotive-Grade Options Available?
Standard LM393 devices are characterised per JEDEC JESD48 package standards. They also undergo environmental stress screening per IEC 60068-2. This covers temperature shock, humidity, and mechanical shock. For automotive applications, the LM393Q from Texas Instruments qualifies to AEC-Q100 Grade 1. Equivalent parts from Diodes Inc. and Nexperia meet the same standard. AEC-Q100 Grade 1 mandates HTRB at 150 °C for 1,000 hours. It also requires HTSL at 150 °C, biased HAST, and ESD per JESD22-A114. PPAP documentation confirming lot traceability is available upon request from authorised distributors. This documentation is mandatory for Tier-1 automotive OEM submissions.
What Is the Expected Reliability and MTBF in a Typical Industrial Application?
Texas Instruments’ data for the LM393 in SOP-8 shows a FIT rate of approximately 0.5–1.0 at 55 °C junction temperature. This corresponds to an MTBF exceeding 1 billion device-hours. Field reliability depends heavily on junction temperature. Operating at 25 °C versus 85 °C can improve MTBF by an order of magnitude. This follows the Arrhenius relationship. Keep output sink current below the 16 mA absolute maximum. Also ensure input voltages remain within the specified common-mode range. Violations of either parameter are the most common cause of premature field failures.
How Does the LM393 Compare to the LM339 and LM311?
The LM339 shares the same internal architecture as the LM393 but houses four channels in a 14-pin package. It is more economical per comparator at higher channel counts. In volume, it typically costs 30–40% less per channel. Also, The LM393 is better when only two channels are needed. It saves board area and simplifies routing. The LM311 is a fundamentally different device. It features both open-collector and emitter outputs. This enables complementary logic driving and RS-232 level interfacing. However, its supply range starts at 5 V. It also draws 4–7 mA — roughly 10× the LM393. This makes it unsuitable for battery applications. For cost-sensitive dual-channel designs at 2 V to 36 V, the LM393 is the default choice. Step up to the LM339 at four or more channels. Choose the LM311 only when complementary outputs or RS-232 compatibility is essential.
What Are Typical MOQs, Lead Times, and Sourcing Options at LCSC?
At LCSC, the LM393DR (SOP-8, commercial grade) is stocked from multiple suppliers. These include WINSOK, JSMSEMI, and Shikues. Cut-tape MOQs start at 1 piece. Typical unit prices are USD 0.03–0.08 at small quantities. Full tape-and-reel reels of 3,000 pieces are priced from USD 0.02 per unit. Branded Texas Instruments LM393DR typically quotes 4–8 weeks lead time. Domestic second-source equivalents are often available from immediate stock. For industrial-grade LM393M or LM393I variants, LCSC carries Nexperia and Diodes Inc. options. Lead times are typically 1–3 weeks in most market conditions. Cross-reference the datasheet temperature suffix before ordering in volume. Request a Certificate of Conformance (CoC) for production lots to verify temperature range compliance.
Conclusion: Choosing the Right LM393 Voltage Comparator for Your Design
The LM393 Voltage Comparator is one of the most widely deployed threshold-detection ICs in the world. Its wide supply range and ultra-low quiescent current make it highly versatile. The open-collector output adds flexibility. Deep second-source availability keeps supply chains resilient. For most dual-channel comparator designs, the LM393DR in SOP-8 is the right starting point. Choose the LM393IDR for industrial or outdoor environments requiring −40 °C to +125 °C operation. Select the AEC-Q100 LM393Q only where automotive PPAP documentation is contractually required. Whatever the grade, the LM393 delivers reliable threshold detection with minimal surrounding circuitry. This combination has driven billions of units into production. All things considered, it will continue to do so for years to come.
Find What You Need on LCSC
Browse all LM393 Voltage Comparator variants — commercial, industrial, and AEC-Q100 qualified — from over 30 manufacturers including Texas Instruments, STMicroelectronics, Nexperia, WINSOK, and JSMSEMI. LCSC stocks millions of units across SOP-8, DIP-8, TSSOP-8, and SOT-23-6 packages, with cut-tape MOQs starting at 1 piece.
