Texas Instruments LM239J

Overview

LM239J from Texas Instruments is a quad voltage comparator IC with open-collector outputs, designed for single- or dual-supply operation across 2–36 VDC (±1 to ±18 VDC). It delivers ±3 mV max input offset voltage, 0.8 mA typical supply current per comparator, and input common-mode range extending to ground - enabling precise threshold detection in industrial control, power monitoring, and analog signal conditioning circuits.

For engineers reviewing the LM239J datasheet, LM239J pinout, LM239J application, or LM239J equivalent, this page provides verified technical context, package mapping to SOIC-14, confirmed electrical specifications including output saturation voltage (250 mV at 4 mA), input bias current (25 nA), and real-world application implementation guidance for limit detection, pulse generation, and wired-OR logic interfacing.

Technical Context

The LM239J integrates four independent high-gain comparators on a monolithic silicon die, each featuring PNP differential input stages enabling rail-to-ground common-mode operation and uncommitted NPN open-collector outputs. Its bias network maintains stable 0.8 mA supply current across 2–36 VDC, independent of supply magnitude.

No internal antisaturation clamps are used, resulting in ultra-low 0.1 nA output leakage current in the OFF state and true open-drain switching capability. The output stage supports wired-OR configurations, pullup to any compatible logic supply (TTL/CMOS/DTL/ECL/MOS), and sink currents up to 16 mA with ≤400 mV saturation voltage at 4 mA.

Key Specifications

Pinout & Package

LM239J is packaged in a 14-pin SOIC (Small Outline Integrated Circuit) with nominal body size 8.65 mm × 3.91 mm. This surface-mount package supports automated assembly and offers thermal resistance θ_JA = 95°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad comparator applications.

Compared with LM239J, LM339N trades temperature range for lower cost in benign environments, while LM2901DT adds automotive qualification and improved robustness at marginally higher price - both retain pin compatibility and open-collector functionality but differ in offset stability and thermal rating.

Availability

LM239J is available at Aetrix Electronics and suitable for industrial automation, power supply supervision, and embedded sensor interface applications requiring stable component supply, long-term lifecycle support, and traceable sourcing from authorized channels.

Supply support for LM239J 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and connectivity technologies, with decades of expertise in precision analog ICs and industrial-grade components.

The LM239J belongs to TI's legacy LMx39-N quad comparator product line, engineered for reliability in industrial control, power management, and signal conditioning where single-supply operation, ground-sensing capability, and open-collector flexibility are essential.

FAQ

What is the operating temperature range for LM239J?

The LM239J is specified for operation from −25°C to +85°C ambient temperature. This industrial-grade range supports deployment in factory automation, motor drives, and power supplies where thermal stress exceeds commercial limits. All key parameters - including input offset voltage (±3 mV max), supply current (0.8 mA typ), and output saturation voltage (250 mV at 4 mA) - are guaranteed across this full range. The LM239J datasheet confirms these limits under Recommended Operating Conditions (Section 6.3).

Does LM239J support dual-supply operation?

Yes, LM239J supports dual-supply operation from ±1 V to ±18 VDC. Its input common-mode voltage range includes ground even when powered by split supplies, and its open-collector outputs remain fully functional with either configuration. When using dual supplies, the GND pin serves as the reference midpoint, and outputs can be pulled up to V+ or down to V− depending on logic requirements. This flexibility is explicitly documented in the LM239J datasheet Section 3 (Description) and Table 6.3.

Can LM239J outputs be wired together?

Yes, LM239J outputs are open-collector and fully compatible with wired-OR configurations. Multiple outputs (e.g., from different channels or multiple LM239J devices) can share a single pullup resistor to implement logic functions like window detection, alarm aggregation, or priority encoding. This behavior stems from the uncommitted NPN collector output stage, which sinks current when active and presents high impedance when inactive - a feature confirmed in Section 7.3 (Feature Description) of the LM239J datasheet.

What is the maximum input voltage allowed on LM239J pins?

The LM239J allows differential input voltages up to 36 VDC without damage, and individual inputs may exceed V+ (up to 30 VDC) as long as the other input remains within the common-mode range. However, input voltages must not go below −0.3 VDC relative to GND (or −0.3 VDC below V− in dual-supply mode) to prevent forward-biasing of internal PNP base-collector junctions. These absolute limits are defined in Section 6.1 (Absolute Maximum Ratings) and reinforced in Section 6.5 notes of the LM239J datasheet.

Is LM239J pin-compatible with LM339N?

Yes, LM239J and LM339N share identical pinout, SOIC-14 package dimensions, and functional pin assignments (e.g., Pin 3 = V+, Pin 12 = GND, Pins 1/2/13/14 = outputs). Both comply with the LMx39-N family pin configuration shown in Section 5 (Pin Configuration and Functions) of the shared datasheet SNOSBJ3E. However, they differ in temperature rating (LM239J: −25°C to +85°C; LM339N: 0°C to +70°C) and guaranteed offset voltage (LM239J: ±3 mV max; LM339N: ±9 mV max at 70°C), so direct substitution requires validation of thermal and precision requirements.