LM139FK Equivalent & Substitute Parts

Part Overview

The LM139FK is a quad differential comparator manufactured by Texas Instruments, designed for general-purpose comparison applications. This device features open-collector, open-drain output configuration and operates across a wide supply voltage range of 2V to 30V (single supply) or ±1V to ±15V (dual supply). The LM139FK is classified as an active product with full RoHS3 compliance and is packaged in a 20-CLCC surface-mount configuration.

Substitute parts are necessary when the original LM139FK becomes unavailable, when alternative packaging formats are required for manufacturing optimization, or when design specifications allow for functionally equivalent alternatives that offer improved availability or cost efficiency while maintaining electrical compatibility.

Substiute Parts

LM139FK

Texas InstrumentsIn Stock: 1112LM139FK Datasheet

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LM2901AS14-13

Diodes IncorporatedIn Stock: 12770LM2901AS14-13 Datasheet

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LM2901QS14-13

Diodes IncorporatedIn Stock: 17638LM2901QS14-13 Datasheet

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LM2901QT14-13

Diodes IncorporatedIn Stock: 7691LM2901QT14-13 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the LM139FK is determined by the following critical parameters:

Functional Equivalence Criteria:

• Quad differential comparator topology (4 elements required)
• General-purpose comparator classification
• Supply voltage range compatibility: minimum 2V single supply or ±1V dual supply capability
• Output current capability of 16mA or greater at 5V
• Operating temperature range encompassing -55°C to 125°C or subset thereof
• Active product status with current manufacturing availability

Electrical Compatibility Parameters:

• Input offset voltage within acceptable tolerance for the application
• Input bias current specifications compatible with signal source impedance
• Quiescent current consumption within system power budget
• Output stage configuration (open-collector, open-drain, CMOS, or TTL) suitable for load interface

Physical Compatibility Parameters:

• Surface-mount packaging format
• Pin count and functional pin assignment compatibility
• RoHS3 compliance certification

The substitute parts identified (LM2901AS14-13, LM2901QS14-13, LM2901QT14-13) meet these criteria through equivalent functional performance, though with variations in package format and output stage configuration.

Parameter Comparison

Engineering Selection Recommendations

LM2901AS14-13 (Diodes Incorporated, 14-SOIC)

This substitute offers the broadest supply voltage range (2V ~ 36V single, ±1V ~ 18V dual) and superior input offset voltage specification (2mV @ 5V versus 5mV for the LM139FK). The 14-SOIC package provides a smaller footprint than the 20-CLCC original. Selection is appropriate for applications where package size optimization is prioritized and the extended supply voltage range provides design margin. RoHS3 compliance and active product status ensure long-term availability.

LM2901QS14-13 (Diodes Incorporated, 14-SOIC, Automotive Grade)

This variant incorporates AEC-Q100 automotive qualification and CMOS/TTL output configuration. Operating temperature range is -40°C to 125°C, which covers the upper portion of the LM139FK specification. Selection is appropriate for automotive applications, industrial environments requiring AEC-Q100 certification, or designs where CMOS/TTL output compatibility is required. Moisture sensitivity level of 1 (Unlimited) indicates superior moisture resistance compared to standard commercial grades.

LM2901QT14-13 (Diodes Incorporated, 14-TSSOP, Automotive Grade)

This variant provides the same automotive-grade qualification and AEC-Q100 certification as the LM2901QS14-13 but in a 14-TSSOP package format. The TSSOP package offers a narrower footprint (4.40mm width) compared to SOIC (3.90mm width) while maintaining the same pin count. Selection is appropriate for space-constrained automotive or industrial applications requiring AEC-Q100 compliance.

All three substitute parts maintain RoHS3 compliance, active product status, and functional equivalence in quad differential comparator topology with 16mA output current capability.

Frequently Asked Questions (FAQ)

Q: Can LM2901AS14-13, LM2901QS14-13, or LM2901QT14-13 directly replace LM139FK in existing designs?

A: Direct replacement requires PCB layout modification due to package format differences. The LM139FK uses 20-CLCC packaging, while all three substitutes use 14-pin SOIC or TSSOP packages. Pin assignment and functional mapping must be verified against device datasheets. Electrical compatibility is confirmed through matching quad differential comparator topology, output current capability (16mA @ 5V), and supply voltage range overlap.

Q: What are the key differences in output stage configuration?

A: The LM139FK specifies open-collector, open-drain output. LM2901AS14-13 does not specify output type in provided documentation. LM2901QS14-13 and LM2901QT14-13 specify CMOS and TTL output configuration. CMOS/TTL outputs provide rail-to-rail switching capability, whereas open-collector outputs require external pull-up resistors. Circuit design modifications may be necessary depending on load interface requirements.

Q: Are the automotive-grade variants (LM2901QS14-13, LM2901QT14-13) suitable for non-automotive applications?

A: Yes. Automotive-grade components with AEC-Q100 qualification meet or exceed commercial-grade specifications and are suitable for any application. The AEC-Q100 certification indicates enhanced reliability testing, extended temperature range validation, and stricter manufacturing controls. These variants are appropriate for industrial, medical, or high-reliability applications where superior component qualification is beneficial.

Q: What is the significance of the operating temperature range difference?

A: The LM139FK operates from -55°C to 125°C. All three substitutes operate from -40°C to 125°C. The LM139FK provides 15°C additional low-temperature operation. Selection of substitutes is appropriate for applications with minimum operating temperature of -40°C or higher. Applications requiring -55°C operation must retain the LM139FK or identify alternative substitutes with matching temperature specifications.

Q: How do input offset voltage specifications affect substitution?

A: Input offset voltage determines comparator accuracy in precision applications. LM139FK specifies 5mV maximum at 5V. LM2901AS14-13 specifies 2mV (superior), while LM2901QS14-13 and LM2901QT14-13 specify 7mV (acceptable for most applications). For high-precision threshold detection, LM2901AS14-13 offers improved performance. For general-purpose applications, all substitutes are functionally equivalent.

Q: What packaging considerations apply to PCB redesign?

A: LM139FK (20-CLCC) requires ceramic leadless carrier footprint. LM2901AS14-13 and LM2901QS14-13 (14-SOIC) require gull-wing lead footprint with 0.154" body width. LM2901QT14-13 (14-TSSOP) requires thin shrink small-outline footprint with 0.173" body width. All are surface-mount configurations. Footprint libraries, solder reflow profiles, and pick-and-place programming require updating for package transitions.

Q: Are all substitutes RoHS3 compliant?

A: Yes. LM139FK, LM2901AS14-13, LM2901QS14-13, and LM2901QT14-13 are all RoHS3 compliant. Environmental compliance is maintained across all substitute options.