Texas Instruments LM139AJ/PB

Overview

LM139AJ/PB from Texas Instruments is a quad precision voltage comparator with open-collector outputs, designed for single- or dual-supply operation across −55°C to +125°C. It delivers ±2 mV max input offset voltage, 0.8 mA supply current per comparator, and input common-mode range extending to ground - enabling threshold detection in industrial sensor interfaces, power supply monitoring, and battery management systems.

For engineers reviewing the LM139AJ/PB datasheet, LM139AJ/PB pinout, LM139AJ/PB application, or LM139AJ/PB equivalent, this page provides verified electrical specifications, CDIP-14 package details, TTL/CMOS-compatible output behavior, and validated alternative options for high-reliability analog-digital interface design.

Technical Context

The LM139AJ/PB integrates four independent PNP-input comparators on a monolithic die, each featuring uncommitted NPN output transistors capable of sinking up to 16 mA with ≤250 mV saturation voltage at 4 mA. Its bias network ensures supply-current independence over 2–36 VDC (±1 to ±18 VDC), and its input stage allows common-mode voltages down to GND even under single-supply operation.

No internal antisaturation clamps are used, yielding ultra-low output leakage (0.1 nA typical) and enabling clean wired-OR configurations. The device operates without oscillation only when hysteresis or input resistors <10 kΩ are applied - a direct consequence of its high gain and susceptibility to stray capacitive coupling during output transitions.

Key Specifications

Pinout & Package

LM139AJ/PB is housed in a 14-pin Ceramic Dual In-line Package (CDIP) with body size 19.56 mm × 6.67 mm, rated for military-grade temperature operation (−55°C to +125°C) and hermetic sealing.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2901N and LM339DR, LM139AJ/PB offers superior temperature range (−55°C to +125°C), tighter offset (2 mV vs. 5–7 mV), lower input bias current (25 nA vs. 250 nA), and hermetic CDIP packaging - making it the only option qualified for aerospace, defense, and extended-temperature industrial use.

Availability

LM139AJ/PB is available at Aetrix Electronics and suitable for industrial power monitoring, automotive battery management, factory automation sensor interfaces, and military-grade signal conditioning requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for LM139AJ/PB 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 and embedded processing technologies, with decades of heritage in precision analog ICs and military-grade components.

LM139AJ/PB belongs to TI's legacy LMx39-N series of quad comparators, engineered specifically for high-reliability, wide-temperature industrial and defense applications where accuracy, robustness, and long-term supply stability are mandatory.

FAQ

What is the maximum operating temperature range for LM139AJ/PB?

The LM139AJ/PB is specified for continuous operation from −55°C to +125°C. This extended temperature range is enabled by its ceramic dual-in-line package (CDIP) and military-grade process, distinguishing it from commercial variants like LM339 or LM2901. All electrical parameters in the datasheet are guaranteed across this full range, making LM139AJ/PB suitable for aerospace, defense, and under-hood automotive applications where thermal resilience is critical.

Does LM139AJ/PB require external pullup resistors on its outputs?

Yes, LM139AJ/PB features open-collector NPN outputs that require external pullup resistors to establish a defined HIGH logic level. The value depends on load capacitance and speed requirements - typically 1–10 kΩ for TTL/CMOS interfacing. Without a pullup, the output remains floating in the HIGH state. This architecture enables wired-OR logic, level translation beyond V+, and direct grounding of loads, which is a core functional feature of the LM139AJ/PB design.

Can LM139AJ/PB operate from a single 3.3 V supply?

Yes, LM139AJ/PB supports single-supply operation down to 2 VDC, so it functions correctly at 3.3 V. However, note that input common-mode range extends only to V+ −1.5 V at 25°C - meaning maximum usable input voltage is ~1.8 V. For full-rail input sensing at 3.3 V, external level-shifting or reference scaling is required. The device's 25 nA input bias current and 2 mV offset remain valid at 3.3 V, preserving accuracy in low-voltage monitoring.

How does LM139AJ/PB differ from LM339 in terms of reliability and packaging?

LM139AJ/PB uses a hermetically sealed ceramic DIP (CDIP) package rated for −55°C to +125°C, while LM339 is typically offered in plastic SOIC or PDIP packages rated for 0°C to +70°C. LM139AJ/PB also specifies tighter input offset (2 mV max vs. 5 mV max for LM339), lower input bias current (25 nA vs. 250 nA), and is manufactured to military screening standards. These differences make LM139AJ/PB appropriate for high-reliability, long-lifecycle, and extreme-environment applications where LM339 is not qualified.

Is hysteresis required when using LM139AJ/PB in comparator circuits?

Yes - hysteresis is strongly recommended for stable operation of LM139AJ/PB. Due to its high gain and susceptibility to stray capacitive coupling between output and input pins, the device can oscillate during output transitions unless positive feedback (hysteresis) is applied or input resistors are kept below 10 kΩ. TI's datasheet explicitly states that socketed evaluation boards will oscillate without hysteresis. A typical implementation uses a resistor divider from output to noninverting input to add 1–10 mV of hysteresis, ensuring clean, bounce-free switching.