LM139FKB Equivalent & Substitute Parts

Part Overview

The LM139FKB is a quad differential comparator manufactured by Texas Instruments, designed for general-purpose comparison applications. This device features open-collector and open-drain output configurations, operating across a wide supply voltage range of 2V to 30V (single supply) or ±1V to ±15V (dual supply). The component is housed in a 20-LCCC surface-mount package and maintains active product status with full RoHS3 compliance.

Substitute parts become necessary when the 20-LCCC package is unavailable, when alternative supply chain sources are required, or when design flexibility permits the use of functionally equivalent devices in different package configurations. The LM2901 series provides direct functional equivalence with enhanced electrical specifications and automotive-grade qualification options.

Substiute Parts

LM139FKB

Texas InstrumentsIn Stock: 1419LM139FKB Datasheet

Current PartRFQ

LM2901AQS14-13

Diodes IncorporatedIn Stock: 20116LM2901AQS14-13 Datasheet

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LM2901AQT14-13

Diodes IncorporatedIn Stock: 19390LM2901AQT14-13 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the LM139FKB is determined by the following critical parameters:

Functional Equivalence Criteria:

• Number of Elements: Must be 4 (quad configuration)
• Output Type: Must include Open-Collector or Open-Drain capability
• Voltage - Supply Range: Must encompass or exceed 2V ~ 30V (single) and ±1V ~ ±15V (dual)
• Current - Output: Must support minimum 16mA @ 5V
• Operating Temperature: Must cover -55°C ~ 125°C or equivalent industrial range

Substitute Parts Identified:

The LM2901AQS14-13 and LM2901AQT14-13 meet all functional equivalence criteria. Both devices are manufactured by Diodes Incorporated and feature the LM2901 base product number, which is a direct functional equivalent to the LM139FKB. These substitutes provide enhanced electrical specifications, including improved input offset voltage (2mV vs. 5mV) and extended supply voltage range (2V ~ 36V single supply, ±1V ~ ±18V dual supply). The primary difference is package configuration: LM2901AQS14-13 uses 14-SOIC packaging, while LM2901AQT14-13 uses 14-TSSOP packaging, both smaller than the original 20-LCCC.

Parameter Comparison

Engineering Selection Recommendations

LM2901AQS14-13 (14-SOIC Package): This substitute is suitable for applications where the 20-LCCC package cannot be accommodated and a standard industrial-grade device is acceptable. The 14-SOIC package provides improved thermal characteristics and reduced board space compared to the original 20-LCCC. This device carries automotive-grade qualification (AEC-Q100) and RoHS3 compliance, making it appropriate for both commercial and automotive applications. The enhanced electrical specifications (2mV input offset vs. 5mV) provide improved accuracy in comparison operations.

LM2901AQT14-13 (14-TSSOP Package): This substitute offers the most compact footprint among the available options, utilizing a 14-TSSOP package. It is recommended for space-constrained designs where board real estate is a primary consideration. Like the LM2901AQS14-13, this device is automotive-qualified (AEC-Q100) and RoHS3 compliant. The electrical performance is identical to the 14-SOIC variant, with the primary distinction being package geometry.

Compatibility Considerations: Both substitute parts operate across extended supply voltage ranges (2V ~ 36V single, ±1V ~ ±18V dual) that exceed the original LM139FKB specifications, ensuring compatibility in all existing applications. The operating temperature range for substitutes (-40°C ~ 125°C) covers the upper portion of the original range (-55°C ~ 125°C); applications requiring operation below -40°C must retain the original LM139FKB.

Frequently Asked Questions (FAQ)

Q: Can LM2901AQS14-13 or LM2901AQT14-13 be used as direct replacements for LM139FKB in existing designs?

A: Yes, both LM2901 variants are functionally equivalent for applications operating within the -40°C to 125°C temperature range. The enhanced electrical specifications (lower input offset voltage, extended supply range) make them suitable drop-in replacements. However, PCB layout modifications are required due to different package configurations (14-pin vs. 20-pin).

Q: What is the primary difference between LM2901AQS14-13 and LM2901AQT14-13?

A: Both devices are electrically identical. The difference is packaging: LM2901AQS14-13 uses 14-SOIC (0.154" width, 3.90mm), while LM2901AQT14-13 uses 14-TSSOP (0.173" width, 4.40mm). Selection depends on PCB layout requirements and available board space.

Q: Are the substitute parts automotive-qualified?

A: Yes, both LM2901AQS14-13 and LM2901AQT14-13 carry AEC-Q100 automotive qualification and are classified as automotive-grade components. The original LM139FKB does not specify automotive qualification.

Q: What is the operating temperature limitation when using substitutes?

A: The LM2901 series operates from -40°C to 125°C, compared to the LM139FKB range of -55°C to 125°C. Applications requiring operation below -40°C must use the original LM139FKB.

Q: Do the substitute parts maintain RoHS3 compliance?

A: Yes, both LM2901AQS14-13 and LM2901AQT14-13 are RoHS3 compliant, matching the environmental compliance status of the original LM139FKB.

Q: How do the electrical specifications compare between the main part and substitutes?

A: The LM2901 substitutes provide improved input offset voltage (2mV vs. 5mV at 5V) and extended supply voltage ranges. Quiescent current is slightly higher (2.5mA vs. 2mA). All other critical parameters (output current, number of elements, output type) are equivalent or superior.

Q: Which substitute should be selected for a new design?

A: For new designs, either LM2901AQS14-13 or LM2901AQT14-13 is recommended based on PCB layout constraints. The 14-TSSOP (LM2901AQT14-13) offers the smallest footprint, while the 14-SOIC (LM2901AQS14-13) provides better thermal performance. Both offer automotive qualification and superior electrical specifications.