LM2940IMPX-12 Equivalent & Substitute Parts

Part Overview

The LM2940IMPX-12 is a linear voltage regulator IC from Texas Instruments, delivering a fixed 12V output at 1A in a SOT-223-4 surface mount package. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement. The device provides positive fixed output regulation with integrated protection features including over-current, over-temperature, reverse polarity, and short-circuit protection, suitable for applications requiring stable 12V power delivery in compact form factors.

Key Parameters

Parameter	Value
Manufacturer	Texas Instruments
Category	Power Management (PMIC)
Output Voltage (Fixed)	12V
Output Current	1A
Input Voltage (Max)	26V
Voltage Dropout (Max)	1V @ 1A
Quiescent Current	10 mA
Operating Temperature Range	-40°C to 85°C
Package Type	SOT-223-4
Mounting Type	Surface Mount
Protection Features	Over Current, Over Temperature, Reverse Polarity, Short Circuit

Substitute Part Grouping Explanation

Substitution for the LM2940IMPX-12 is determined by the following critical parameters: fixed 12V output voltage, positive output configuration, surface mount SOT-223 package family, and integrated protection features. Substitute parts must maintain electrical compatibility across input voltage range (up to 26V), output voltage (12V fixed), and protection mechanisms.

Substitutes are grouped into two categories:

Direct Manufacturer Equivalents (Texas Instruments LM2940 Series): Parts LM2940IMPX-12/NOPB and LM2940IMP-12/NOPB maintain identical electrical specifications and package designations. These differ only in product status and packaging format (Cut Tape & Digi-Reel versus bulk inventory).

Parametric Equivalents (Microchip MIC2920A Series): Parts MIC2920A-12WS and MIC2920A-12WS-TR provide functional equivalence with modified output current rating (400mA versus 1A) and different quiescent current characteristics. These are suitable where output current requirements do not exceed 400mA and represent manufacturer-recommended alternatives.

Parameter Comparison

Parameter	LM2940IMPX-12	LM2940IMPX-12/NOPB	LM2940IMP-12/NOPB	MIC2920A-12WS	MIC2920A-12WS-TR
Manufacturer	Texas Instruments	Texas Instruments	Texas Instruments	Microchip Technology	Microchip Technology
Product Status	Obsolete	Active	Active	Active	Active
Output Voltage	12V	12V	12V	12V	12V
Output Current	1A	1A	1A	400mA	400mA
Input Voltage (Max)	26V	26V	26V	26V	26V
Voltage Dropout (Max)	1V @ 1A	1V @ 1A	1V @ 1A	0.75V @ 400mA	0.75V @ 400mA
Quiescent Current	10 mA	10 mA	10 mA	300 µA	300 µA
Operating Temperature	-40°C to 85°C	-40°C to 85°C	-40°C to 85°C	-40°C to 125°C	-40°C to 125°C
Package Type	SOT-223-4	SOT-223-4	SOT-223-4	SOT-223-3	SOT-223-3
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	3 (168 Hours)	3 (168 Hours)

Engineering Selection Recommendations

For applications requiring full 1A output current capacity with active product support, select LM2940IMPX-12/NOPB or LM2940IMP-12/NOPB. Both parts are active products with ROHS3 compliance and identical electrical performance to the obsolete LM2940IMPX-12. The primary distinction is packaging format: LM2940IMPX-12/NOPB is supplied in Cut Tape & Digi-Reel format, while LM2940IMP-12/NOPB is available in bulk inventory.

For applications with output current requirements not exceeding 400mA, MIC2920A-12WS and MIC2920A-12WS-TR provide manufacturer-recommended alternatives from Microchip Technology. These parts offer extended operating temperature range (-40°C to 125°C versus -40°C to 85°C), lower quiescent current (300 µA versus 10 mA), and improved dropout voltage characteristics (0.75V @ 400mA). MIC2920A-12WS-TR is supplied in Cut Tape & Digi-Reel format, while MIC2920A-12WS is supplied in Tube packaging. Both Microchip parts are ROHS3 compliant with Moisture Sensitivity Level 3.

Frequently Asked Questions (FAQ)

Q: Can LM2940IMPX-12/NOPB directly replace the obsolete LM2940IMPX-12?

A: Yes. LM2940IMPX-12/NOPB is a direct equivalent with identical electrical specifications, output current rating (1A), voltage dropout characteristics, and SOT-223-4 package. The primary difference is active product status and ROHS3 compliance.

Q: What is the key limitation when substituting with MIC2920A-12WS or MIC2920A-12WS-TR?

A: Output current is reduced from 1A to 400mA. These parts are suitable only for applications where load current does not exceed 400mA. Designs requiring full 1A output must use LM2940IMPX-12/NOPB or LM2940IMP-12/NOPB.

Q: Are there package compatibility differences between substitute parts?

A: Yes. LM2940 series parts use SOT-223-4 package (4 pins), while MIC2920A series uses SOT-223-3 package (3 pins). PCB layout modifications are required when switching between these package types. Pin configurations differ and are not interchangeable without redesign.

Q: What are the moisture sensitivity implications for long-term storage?

A: LM2940 series parts have Moisture Sensitivity Level 1 (unlimited shelf life). MIC2920A series parts have Moisture Sensitivity Level 3, requiring storage in controlled humidity conditions (168-hour floor life after moisture exposure). This affects procurement and inventory management practices.

Q: Which substitute offers the best thermal performance?

A: MIC2920A-12WS and MIC2920A-12WS-TR support extended operating temperature range to 125°C (versus 85°C for LM2940 series). However, this advantage applies only within the 400mA output current limit of the Microchip devices.

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