Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

Home > Products > Integrated Circuits (ICs) > Linear > Comparators

Texas Instruments LM139FKB

Name: LM139FKB
Brand: Texas Instruments
SKU: LM139FKB
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: LM139FKB

Manufacturer:: Texas Instruments

Category:: Comparators

Package:: 20-CLCC

Datasheet:: LM139FKB.pdf

Description:: QUAD DIFFERENTIAL COMPARATOR 20-

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:1,831

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

LM139FKB from Texas Instruments is a quad differential voltage comparator with open-collector outputs, designed for military-grade operation across –55°C to +125°C. It supports single-supply (2 V to 30 V) or dual-supply (±1 V to ±15 V) operation, features 2 mV typical input offset voltage, 25 nA typical input bias current, and common-mode input range extending to ground - enabling use in power supervision, level translation, and oscillator circuits.

For engineers reviewing the LM139FKB datasheet, LM139FKB pinout, LM139FKB application, or LM139FKB equivalent, this page delivers verified electrical parameters, LCCC-20 package mapping, military-temperature performance data, and direct alternative part comparisons - all grounded in TI's SLCS160 production datasheet and orderable packaging documentation.

Technical Context

The LM139FKB implements four independent comparators using PNP Darlington-pair inputs, delivering high gain and low input bias current while maintaining rail-to-rail common-mode capability down to ground. Its open-collector NPN output stage enables wired-AND logic and flexible pull-up voltage selection up to 36 V.

It operates with supply-independent 0.8 mA typical supply current, supports differential input voltages up to ±36 V, and achieves 1.3 µs typical response time (100 mV overdrive, 5.1 kΩ pull-up, 15 pF load). Input offset voltage remains stable across the full –55°C to +125°C military temperature range.

Key Specifications

Parameter	Value and Actual Design Meaning
Supply Voltage Range	Single: 2 V to 30 V; Dual: ±1 V to ±15 V - enables direct interface with 3.3 V, 5 V, 12 V, and 24 V systems without level shifting.
Input Offset Voltage	2 mV (typ), 9 mV (max, –55°C to +125°C) - ensures accurate threshold detection in precision monitoring applications.
Input Bias Current	25 nA (typ), 300 nA (max, –55°C to +125°C) - minimizes loading on high-impedance sensor or reference sources.
Common-Mode Input Range	0 V to V_CC – 2 V - allows direct sensing of signals referenced to ground, including battery voltage and current-sense amplifiers.
Output Configuration	Open-collector NPN - supports TTL/MOS/CMOS compatibility, wired-AND logic, and level translation up to 36 V.
Response Time	1.3 µs (typ, 100 mV overdrive) - suitable for medium-speed control loops, window comparators, and pulse-width modulation feedback.
Operating Temperature	–55°C to +125°C - qualified per MIL-PRF-38535 for aerospace, defense, and harsh-environment industrial use.

Pinout & Package

LCCC (FK) package: 20-pin leadless ceramic chip carrier, 8.90 mm × 8.90 mm body, 1.27 mm pitch, hermetically sealed, with no internal connection on Pin 1.

Pin/Terminal	Circuit Role	Design Meaning
1	No connect	No internal connection - must be left floating or tied to ground per layout guidelines; not usable as signal or power terminal.
2, 3, 19, 20	Comparator outputs (1OUT–4OUT)	Open-collector NPN drains - require external pull-up resistors; support wired-AND logic and voltage-level translation.
4, 6, 8, 9, 12, 13, 14, 16	Input terminals (1IN+ through 4IN−)	Differential input pairs - each comparator has dedicated IN+ and IN−; inputs tolerate up to 30 V regardless of supply.
18	GND	Ground reference for all comparators and internal circuitry - must be low-impedance connection for stable common-mode operation.
4	V_CC	Positive supply pin - accepts 2 V to 30 V; powers all four comparators; decoupling capacitor required for noise immunity.

Key Features

Feature	Design Value
Rail-to-ground common-mode input	Enables direct interfacing with ground-referenced sensors (e.g., shunt-based current monitors) without level-shifting circuitry.
Supply-current independence	0.8 mA typical ICC across full 2 V–30 V supply range - simplifies power budgeting in multi-rail systems.
High differential input voltage tolerance	±36 V rating - protects against transients and allows direct comparison of signals exceeding supply rails.
MIL-PRF-38535 compliance	All parameters tested over –55°C to +125°C - eliminates need for derating or additional qualification testing in defense programs.
Open-collector output flexibility	Supports mixed-voltage system interfacing (e.g., 3.3 V MCU reading 24 V signal) via external pull-up to desired logic rail.

Applications

Power Supervision	Oscillator Circuits
Use Scenario: Monitoring DC bus voltage in avionics power distribution units to trigger undervoltage lockout or fault reporting. IC Role / Device Role / Timing Role: Quad comparator configured as window detector and threshold comparator - two channels monitor upper/lower limits, two provide hysteresis and status flag generation. Use Value: Leverages rail-to-ground input range and ±36 V differential tolerance to directly sense 28 V aircraft buses without attenuation or isolation.	Use Scenario: Generating square-wave clock signals in radiation-hardened timing modules where external crystal oscillators are unavailable. IC Role / Device Role / Timing Role: Comparator used in relaxation oscillator configuration with RC network and hysteresis feedback - one channel forms core oscillator, others provide buffered outputs or enable gating. Use Value: Stable 1.3 µs response and low 25 nA input bias ensure predictable frequency accuracy across –55°C to +125°C without trimming.
Logic Voltage Translation	Peak Detector Interface
Use Scenario: Converting analog sensor outputs (0–10 V) into 3.3 V logic levels for FPGA input in engine control units. IC Role / Device Role / Timing Role: Single comparator channel acting as level translator - IN− tied to reference voltage, IN+ receives sensor signal, OUT pulled up to 3.3 V. Use Value: Open-collector output and wide supply range allow seamless bridging between 10 V analog domain and 3.3 V digital domain without additional level-shift ICs.	Use Scenario: Capturing peak amplitude of transient RF envelope signals in electronic warfare receivers before ADC sampling. IC Role / Device Role / Timing Role: Comparator drives reset logic for external sample-hold circuit - output triggers discharge when input falls below stored peak value. Use Value: Low 2 mV input offset and fast 1.3 µs response minimize tracking error during rapid envelope decay, preserving signal fidelity.

Power Supervision

Oscillator Circuits

Use Scenario: Monitoring DC bus voltage in avionics power distribution units to trigger undervoltage lockout or fault reporting.

IC Role / Device Role / Timing Role: Quad comparator configured as window detector and threshold comparator - two channels monitor upper/lower limits, two provide hysteresis and status flag generation.

Use Value: Leverages rail-to-ground input range and ±36 V differential tolerance to directly sense 28 V aircraft buses without attenuation or isolation.

Use Scenario: Generating square-wave clock signals in radiation-hardened timing modules where external crystal oscillators are unavailable.

IC Role / Device Role / Timing Role: Comparator used in relaxation oscillator configuration with RC network and hysteresis feedback - one channel forms core oscillator, others provide buffered outputs or enable gating.

Use Value: Stable 1.3 µs response and low 25 nA input bias ensure predictable frequency accuracy across –55°C to +125°C without trimming.

Logic Voltage Translation

Peak Detector Interface

Use Scenario: Converting analog sensor outputs (0–10 V) into 3.3 V logic levels for FPGA input in engine control units.

IC Role / Device Role / Timing Role: Single comparator channel acting as level translator - IN− tied to reference voltage, IN+ receives sensor signal, OUT pulled up to 3.3 V.

Use Value: Open-collector output and wide supply range allow seamless bridging between 10 V analog domain and 3.3 V digital domain without additional level-shift ICs.

Use Scenario: Capturing peak amplitude of transient RF envelope signals in electronic warfare receivers before ADC sampling.

IC Role / Device Role / Timing Role: Comparator drives reset logic for external sample-hold circuit - output triggers discharge when input falls below stored peak value.

Use Value: Low 2 mV input offset and fast 1.3 µs response minimize tracking error during rapid envelope decay, preserving signal fidelity.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
LM139JB	Same die, CDIP-14 package (7.60 mm × 21.30 mm); higher thermal resistance (R_θJA = 89.5°C/W vs. 82.5°C/W for FK).	Less compact footprint; requires larger PCB area; lower thermal efficiency in high-power-density designs.	Select LM139JB only when legacy CDIP-14 socket compatibility or manual prototyping is required.
LM139WB	Same die, CFP-14 package (6.29 mm × 9.20 mm); hermetic metal-ceramic seal; R_θJA = 156.2°C/W.	Superior hermeticity for vacuum or corrosive environments; significantly higher thermal impedance limits continuous power dissipation.	Choose LM139WB for space-grade or high-reliability sealed-chamber applications where LCCC moisture sensitivity is a concern.

Compared with LM139JB and LM139WB, the LM139FKB offers the smallest footprint (8.90 mm × 8.90 mm), lowest junction-to-ambient thermal resistance among hermetic quad comparators, and optimized pinout for high-density routing - making it preferred for modern compact military electronics where board space and thermal management are critical.

Availability

LM139FKB is available at Aetrix Electronics and suitable for power supervision, oscillator design, logic voltage translation, and peak detector interface applications requiring stable component supply across extended temperature and long product lifecycles.

Supply support for LM139FKB 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 company specializing in analog and embedded processing technologies, with leadership in high-reliability, military-qualified components.

The LM139-MIL product line delivers quad comparators engineered for mission-critical aerospace, defense, and industrial control systems operating across –55°C to +125°C - emphasizing parametric stability, hermetic packaging, and MIL-PRF-38535 test rigor.

FAQ

What is the maximum supply voltage rating for LM139FKB?

The LM139FKB has an absolute maximum supply voltage of 36 V, but its recommended operating range is 2 V to 30 V per the SLCS160 datasheet. Operation at 36 V is permissible only under short-duration stress conditions and not intended for continuous use. For reliable long-term operation, keep V_CC ≤ 30 V, especially at elevated temperatures.

Does LM139FKB support dual-supply operation?

Yes, LM139FKB supports dual-supply operation with ±1 V to ±15 V (tested) or ±1 V to ±18 V (absolute max). The key constraint is that the difference between supplies must be 2 V to 36 V, and the positive supply must be at least 1.5 V more positive than the input common-mode voltage. This enables use in bipolar signal conditioning stages.

What is the function of Pin 1 on the LM139FKB LCCC package?

Pin 1 on the LM139FKB is labeled "NC" (no connect) in TI's official pinout documentation and has no internal connection. It must remain unconnected - neither grounded nor tied to any voltage - to avoid unintended coupling or mechanical stress on the ceramic package. Layout guidelines recommend leaving it floating or optionally grounding it only if required by board-level EMI mitigation.

How does the open-collector output of LM139FKB interface with CMOS logic?

The LM139FKB open-collector output interfaces with CMOS logic by adding an external pull-up resistor to the desired logic rail (e.g., 3.3 V or 5 V). When the comparator asserts low, the NPN sink conducts; when inactive, the output floats high-impedance. This avoids bus contention and allows mixed-voltage interoperation - a key advantage confirmed in TI's application note on level translation using LM139-MIL devices.

Is LM139FKB compliant with MIL-PRF-38535?

Yes, LM139FKB is explicitly characterized and tested per MIL-PRF-38535 requirements, with all parameters verified across the full –55°C to +125°C temperature range. The "MIL" suffix, J-STD-002 qualification, and inclusion in TI's military data sheet SLCS160 confirm its compliance - making it suitable for DoD-accredited hardware without additional screening.

LM139FKB Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Package/Case:: 20-CLCC

Series:: -

Packaging:: Tube

Product Status:: Active

Type:: General Purpose

Number of Elements:: 4

Output Type:: Open-Collector, Open-Drain

Voltage - Supply, Single/Dual (±):: 2V ~ 30V, ±1V ~ 15V

:: 5mV @ 5V

Voltage - Input Offset (Max):: 0.1µA @ 5V

Current - Input Bias (Max):: 16mA @ 5V

Current - Output (Typ):: 2mA

Current - Quiescent (Max):: -

CMRR, PSRR (Typ):: 300ns (Typ)

Propagation Delay (Max):: -

Hysteresis:: -55°C ~ 125°C

Operating Temperature:: -

Grade:: -

Qualification:: Surface Mount

:: 20-LCCC (8.89x8.89)

LM139FKB FAQ

1.How can I place an order for LM139FKB through Aetrix?

Please submit a Request for Quotation (RFQ) for LM139FKB on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for LM139FKB reliable?

The price and inventory of LM139FKB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM139FKB is usually 5 days.

3.What payment methods are accepted for LM139FKB?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM139FKB transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for LM139FKB?

LM139FKB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your LM139FKB order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for LM139FKB?

For technical support, including LM139FKB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM139FKB requirements.

6.How does Aetrix verify that LM139FKB is sourced from the original manufacturer or authorized distributors?

All LM139FKB products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LM139FKB meets industry standards.

7.What is the process for return or replacement of LM139FKB?

All LM139FKB units undergo pre-shipment inspection (PSI). If there is an issue with LM139FKB, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The LM139FKB part is unused and in its original packaging.

Return procedure for LM139FKB:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

Tech Hub

2026-09-03 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-01 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…

2026-08-21 What Is an LED Driver? Types, Circuits, Dimming, and Selection

An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…

2026-08-18 Operational Amplifier (Op Amp): Basics, Configurations, Feedback and Applications

Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…

2026-08-14 Jumper Cables: How to Use, Connect and Choose Them Safely

Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…