LM2991T Equivalent & Substitute Parts

Part Overview

The LM2991T is a linear voltage regulator IC from Texas Instruments designed for negative adjustable output applications. It delivers 1A output current with a fixed dropout voltage of 1V at rated load and operates across an input voltage range of -26V maximum. The device features integrated over-temperature and short-circuit protection, making it suitable for precision negative voltage regulation in industrial and commercial applications.

The LM2991T carries a Last Time Buy product status, indicating that Texas Instruments has discontinued active production. This status necessitates identification of equivalent substitute parts to ensure design continuity and supply chain reliability for ongoing production requirements.

Key Parameters

Parameter	Value
Manufacturer	Texas Instruments
Category	Power Management (PMIC)
Output Configuration	Negative
Output Type	Adjustable
Voltage - Input (Max)	-26V
Voltage - Output (Min/Fixed)	-3V
Voltage - Output (Max)	-24V
Current - Output	1A
Voltage Dropout (Max)	1V @ 1A
Package / Case	TO-220-5
Operating Temperature	-40°C ~ 125°C
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitute parts for the LM2991T are determined by strict equivalence across the following critical parameters:

Output configuration (Negative)
Output type (Adjustable)
Voltage specifications (Input max -26V, Output range -3V to -24V)
Current rating (1A output)
Dropout voltage (1V @ 1A)
Package type (TO-220-5)
Regulatory compliance (ROHS3, REACH Unaffected)

The identified substitutes maintain identical electrical performance characteristics and mechanical compatibility. Variations in product status and packaging lead finish do not affect functional interchangeability.

Parameter Comparison

Parameter	LM2991T	LM2991T/NOPB	LM2991T/LF03
Manufacturer	Texas Instruments	Texas Instruments	Texas Instruments
Output Configuration	Negative	Negative	Negative
Output Type	Adjustable	Adjustable	Adjustable
Voltage - Input (Max)	-26V	-26V	-26V
Voltage - Output (Min/Fixed)	-3V	-3V	-3V
Voltage - Output (Max)	-24V	-24V	-24V
Current - Output	1A	1A	1A
Voltage Dropout (Max)	1V @ 1A	1V @ 1A	1V @ 1A
Package / Case	TO-220-5	TO-220-5	TO-220-5 Formed Leads
Operating Temperature	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C
Product Status	Last Time Buy	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

Both LM2991T/NOPB and LM2991T/LF03 are direct functional equivalents to the LM2991T. The primary distinction lies in product status and packaging lead finish:

LM2991T/NOPB maintains Active product status with standard TO-220-5 packaging, providing the most straightforward replacement path for new designs and ongoing production.

LM2991T/LF03 is also Active with formed lead configuration in the TO-220-5 package, suitable for applications requiring specific lead geometry or automated insertion processes.

All three variants maintain identical electrical performance, thermal characteristics, and regulatory compliance certifications (ROHS3 Compliant, REACH Unaffected). Selection between active substitutes should be based on packaging lead requirements and supplier availability.

Frequently Asked Questions (FAQ)

Q: Can LM2991T/NOPB and LM2991T/LF03 be used interchangeably with the original LM2991T?

A: Yes. Both substitutes provide identical electrical performance across all specified parameters including voltage regulation range, output current, dropout voltage, and thermal operating range. The differences in packaging lead finish do not affect functional compatibility.

Q: What does the Last Time Buy status mean for the LM2991T?

A: Last Time Buy indicates that Texas Instruments has ceased production of this part number. Existing inventory may be available through authorized distributors, but long-term supply cannot be guaranteed. Migration to active substitute part numbers is recommended for new designs and future production runs.

Q: Are there differences between the TO-220-5 and TO-220-5 Formed Leads packages?

A: Both are TO-220-5 package types with identical electrical and thermal characteristics. The formed leads variant (LM2991T/LF03) features pre-shaped leads optimized for specific insertion or assembly processes. Standard leads (LM2991T/NOPB) are straight and suitable for manual or standard automated insertion.

Q: Do all three part numbers meet the same compliance requirements?

A: Yes. LM2991T, LM2991T/NOPB, and LM2991T/LF03 are all ROHS3 Compliant and REACH Unaffected, meeting identical regulatory standards for industrial and commercial applications.

Q: Which substitute should be selected for new production designs?

A: LM2991T/NOPB is recommended for new designs due to its Active product status and standard TO-220-5 packaging configuration. This ensures long-term supply availability and compatibility with standard assembly processes.

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