LM2940IMP-5.0 Equivalent & Substitute Parts

Part Overview

The LM2940IMP-5.0 is a linear voltage regulator IC from Texas Instruments, delivering fixed 5V output at 1A in a SOT-223-4 surface mount package. This device is classified as Last Time Buy, indicating discontinued production. The part provides positive fixed output configuration with integrated protection features including over-current, over-temperature, reverse polarity, and short-circuit protection. Finding equivalent and substitute parts is necessary due to the Last Time Buy status and to identify alternative sources with active production status.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	5V
Output Current	1A
Input Voltage (Max)	26V
Voltage Dropout (Max)	1V @ 1A
Quiescent Current	10 mA
PSRR	64dB (120Hz)
Operating Temperature Range	-40°C ~ 85°C
Package	SOT-223-4
Protection Features	Over Current, Over Temperature, Reverse Polarity, Short Circuit
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution logic is based on the following critical parameters: fixed 5V output voltage, output current capability, maximum input voltage rating, voltage dropout characteristics, package type, and protection features. Parts are grouped into three categories:

Direct Equivalents (Same Manufacturer, Same Base Series): Parts maintaining identical electrical specifications and the same base product number (LM2940) with different packaging or product status designations.

Parametric Equivalents (Same Manufacturer, Extended Specifications): Parts from the same manufacturer with matching or superior electrical performance characteristics, enabling direct functional replacement.

Manufacturer-Recommended Alternatives (Different Manufacturer, Compatible Specifications): Parts from Analog Devices Inc. that meet or exceed the electrical requirements of the LM2940IMP-5.0, suitable for applications requiring equivalent or enhanced performance.

Parameter Comparison

Part Number	Manufacturer	Output Voltage	Output Current	Input Voltage (Max)	Dropout @ Rated Current	Quiescent Current	Package	Operating Temp	Product Status
LM2940IMP-5.0	Texas Instruments	5V	1A	26V	1V @ 1A	10 mA	SOT-223-4	-40°C ~ 85°C	Last Time Buy
LM2940IMP-5.0/NOPB	Texas Instruments	5V	1A	26V	1V @ 1A	10 mA	SOT-223-4	-40°C ~ 85°C	Active
LM2940IMPX-5.0/NOPB	Texas Instruments	5V	1A	26V	1V @ 1A	10 mA	SOT-223-4	-40°C ~ 85°C	Active
LT1121CST-5#PBF	Analog Devices Inc.	5V	150mA	30V	0.7V @ 150mA	50 µA	SOT-223-3	0°C ~ 125°C	Active
LT1121CST-5#TRPBF	Analog Devices Inc.	5V	150mA	30V	0.7V @ 150mA	50 µA	SOT-223-3	0°C ~ 125°C	Active
LT1121IST-5#PBF	Analog Devices Inc.	5V	150mA	30V	0.7V @ 150mA	50 µA	SOT-223-3	-40°C ~ 125°C	Active
LT1121IST-5#TRPBF	Analog Devices Inc.	5V	150mA	30V	0.7V @ 150mA	50 µA	SOT-223-3	-40°C ~ 125°C	Active
LT1129CST-5#PBF	Analog Devices Inc.	5V	700mA	30V	0.7V @ 700mA	70 µA	SOT-223-3	0°C ~ 125°C	Active
LT1129CST-5#TRPBF	Analog Devices Inc.	5V	700mA	30V	0.7V @ 700mA	70 µA	SOT-223-3	0°C ~ 125°C	Active
LT1129IST-5#PBF	Analog Devices Inc.	5V	700mA	30V	0.7V @ 700mA	70 µA	SOT-223-3	-40°C ~ 125°C	Active
LT1129IST-5#TRPBF	Analog Devices Inc.	5V	700mA	30V	0.7V @ 700mA	70 µA	SOT-223-3	-40°C ~ 125°C	Active

Engineering Selection Recommendations

Direct Replacement (Same Manufacturer): LM2940IMP-5.0/NOPB and LM2940IMPX-5.0/NOPB are direct functional equivalents with Active product status. Both maintain identical electrical specifications and package configuration. Selection between these variants depends on packaging requirements (Cut Tape & Digi-Reel vs. standard packaging).

Alternative Source (Analog Devices Inc.): The LT1121 and LT1129 series from Analog Devices Inc. provide active production alternatives with enhanced specifications. The LT1121 series (150mA output) is suitable for applications with lower current requirements, while the LT1129 series (700mA output) accommodates higher current demands. Both series feature lower quiescent current (50-70 µA vs. 10 mA), higher maximum input voltage (30V vs. 26V), and lower dropout voltage (0.7V vs. 1V). The LT1121IST-5#TRPBF and LT1129IST-5#TRPBF variants support the extended operating temperature range (-40°C ~ 125°C) matching the original part's lower temperature limit.

All substitute parts maintain ROHS3 compliance and MSL Level 1 rating. Package differences (SOT-223-3 vs. SOT-223-4) require PCB layout verification.

Frequently Asked Questions (FAQ)

Q: Can LM2940IMP-5.0/NOPB be used as a direct replacement for LM2940IMP-5.0?

A: Yes. Both parts share identical electrical specifications, output voltage (5V), output current (1A), maximum input voltage (26V), dropout voltage (1V @ 1A), and operating temperature range (-40°C ~ 85°C). The primary difference is product status; LM2940IMP-5.0/NOPB is Active while the original is Last Time Buy. PCB footprint compatibility is maintained.

Q: What are the key differences between LT1121 and LT1129 series alternatives?

A: The primary difference is output current capability. LT1121 series delivers 150mA maximum output current, while LT1129 series delivers 700mA. Both maintain 5V fixed output voltage and SOT-223-3 package. For applications requiring the full 1A output of the original LM2940IMP-5.0, the LT1129 series is the appropriate selection. For lower current applications, LT1121 series offers lower quiescent current (50 µA vs. 70 µA).

Q: Are there package compatibility considerations when substituting with Analog Devices parts?

A: Yes. The original LM2940IMP-5.0 uses SOT-223-4 package, while LT1121 and LT1129 alternatives use SOT-223-3 package. Both are surface mount packages with similar footprints, but pin configuration differs. PCB layout and schematic verification is required before substitution.

Q: Which substitute part supports the full operating temperature range of the original?

A: LT1121IST-5#TRPBF, LT1121IST-5#PBF, LT1129IST-5#TRPBF, and LT1129IST-5#PBF all support -40°C ~ 125°C operating temperature range, which exceeds the original part's -40°C ~ 85°C specification. The "I" designation in the part number indicates industrial temperature range.

Q: What is the significance of the #TRPBF and #PBF suffixes in Analog Devices part numbers?

A: #TRPBF indicates Cut Tape & Digi-Reel packaging, while #PBF indicates Tube packaging. Both are equivalent in electrical performance; selection depends on procurement and assembly requirements.

Q: Do all substitute parts maintain RoHS3 compliance?

A: Yes. All listed substitute parts maintain ROHS3 Compliant status and MSL Level 1 (Unlimited) moisture sensitivity rating, matching the original LM2940IMP-5.0 specifications.

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