STMicroelectronics LM393QT

Overview

LM393QT from STMicroelectronics is a dual low-voltage comparator IC designed for single-supply operation from 2 V to 36 V (or ±1 V to ±18 V), featuring ±1 mV typical input offset voltage, 20 nA typical input bias current, and 0.45 mA supply current per comparator. It supports ground-sensing inputs and TTL/CMOS-compatible open-collector outputs, commonly used in voltage monitoring, zero-crossing detection, and level-shifting circuits.

For engineers reviewing the LM393QT datasheet, LM393QT pinout, LM393QT application, or LM393QT equivalent, key selection criteria include input common-mode range including ground, low output saturation voltage (80 mV at 4 mA sink), differential input voltage tolerance up to supply rails, ESD robustness (2 kV HBM), and compatibility with DFN8 2×2 footprint constraints in space-constrained industrial sensing designs.

Technical Context

The LM393QT implements two independent PNP-input comparators with rail-to-rail differential input capability and an input common-mode range extending to ground-enabling direct interface with sensors and reference voltages referenced to system ground under single-supply conditions. Its open-collector outputs support wired-OR logic and flexible pull-up configurations across logic families.

Designed for low-power industrial and consumer systems, it delivers 1.3 μs typical response time with 100 mV input step and 5 mV overdrive, while maintaining stable performance across 0 °C to +70 °C ambient temperature and supply voltages from 2 V to 36 V. The DFN8 2×2 package provides thermal resistance of 57 °C/W (junction-to-ambient) and supports exposed-pad grounding for improved thermal and EMI performance.

Key Specifications

Pinout & Package

LM393QT is packaged in a 2 mm × 2 mm DFN8 (8-pin dual flat no-lead) with wettable flanks and an exposed thermal pad. The pad may be left floating or connected to ground for improved thermal dissipation and noise immunity. Pin 1 is marked by a dot or chamfered corner.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual low-voltage comparator applications.

Compared with LM393DT and TLV3702IDR, the LM393QT uniquely balances wide supply range (2–36 V), ground-sensing capability, DFN8 space efficiency, and proven industrial temperature rating-making it optimal for cost-sensitive, thermally constrained, and multi-voltage embedded monitoring.

Availability

LM393QT is available at Aetrix Electronics and suitable for industrial voltage monitoring, AC zero-crossing detection, battery management systems, and sensor interface circuits requiring stable component supply across automotive-grade extended temperature programs and long-lifecycle production runs.

Supply support for LM393QT includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, delivering intelligent power, sensing, connectivity, and microcontroller solutions for industrial, automotive, and consumer markets.

The LM393 series belongs to ST's precision analog comparators product line, engineered for robust performance in harsh industrial environments-including wide temperature operation, high ESD tolerance, and ground-referenced single-supply functionality.

FAQ

What is the maximum allowable differential input voltage for LM393QT?

The LM393QT supports a differential input voltage range equal to the full supply voltage-up to ±36 V for dual supplies or 36 V for single supply. This allows direct connection of signals exceeding the supply rails (e.g., transducer outputs or fault transients), provided the individual input voltages remain within −0.3 V to VCC+ + 0.3 V per absolute maximum ratings.

Can LM393QT drive a 5 V TTL load directly?

Yes-LM393QT's open-collector output can sink up to 18 mA with 80 mV saturation voltage at 4 mA, ensuring reliable logic-low assertion into standard 5 V TTL inputs. A pull-up resistor to 5 V (e.g., 10 kΩ) establishes the logic-high level; no level-shifting circuitry is needed for TTL compatibility.

Is the exposed thermal pad on the DFN8 package required to be grounded?

No-the exposed pad on the LM393QT DFN8 package may be left electrically floating or connected to GND. Grounding improves thermal performance (reducing R_thJA) and lowers EMI susceptibility, but is not mandatory for functional operation per STMicroelectronics datasheet DS0443 Rev 17.

Does LM393QT support dual-supply operation with asymmetric rails?

Yes-LM393QT operates with split supplies such as +12 V / −5 V, as long as the total supply voltage (VCC+ − VCC−) remains between 2 V and 36 V. Input common-mode range extends from VCC− to (VCC+ − 1.5 V), so asymmetric rails require verifying that both inputs stay within this window for valid comparison.