LP5951MFX-2.5 Linear Voltage Regulator — Equivalent & Substitute Parts

Part Overview

The LP5951MFX-2.5 is a linear voltage regulator IC manufactured by Texas Instruments, designed to deliver a fixed 2.5V output at 150mA in a SOT-23-5 surface mount package. This part is classified as obsolete, which necessitates identification of active equivalent and substitute components for new designs or production continuity. The device provides positive fixed output regulation with integrated enable control, overcurrent protection, over-temperature protection, and short-circuit protection across an operating temperature range of -40°C to 125°C.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	2.5V
Output Current	150mA
Input Voltage (Max)	5.5V
Dropout Voltage (Max)	0.35V @ 150mA
Quiescent Current	55 µA
PSRR	60dB ~ 50dB (100Hz ~ 10kHz)
Package	SOT-23-5 (SC-74A)
Operating Temperature	-40°C ~ 125°C
Protection Features	Overcurrent, Over-Temperature, Short-Circuit
Control Features	Enable

Substitute Part Grouping Explanation

Substitution of the LP5951MFX-2.5 is determined by the following critical parameters:

Output Voltage: 2.5V fixed output is mandatory
Output Current Capability: Minimum 150mA required; higher ratings are acceptable
Input Voltage Range: Maximum 5.5V or higher
Package Type: SOT-23-5 (SC-74A) surface mount package
Dropout Voltage: Lower values improve efficiency; values at or below 0.35V @ 150mA are preferred
Operating Temperature Range: -40°C to 125°C or compatible subset
Protection Features: Overcurrent and over-temperature protection required
Control Features: Enable pin functionality required

Substitute parts are grouped into three categories:

Direct Manufacturer Equivalents — Texas Instruments parts with identical electrical specifications and active product status
Parametric Equivalents — Parts from the same manufacturer meeting all electrical requirements with packaging variations
Manufacturer-Recommended Alternatives — Parts from other manufacturers meeting or exceeding electrical specifications with active product status

Parameter Comparison

Part Number	Manufacturer	Output Voltage	Output Current	Input Voltage (Max)	Dropout Voltage (Max)	Quiescent Current	Package	Operating Temp	Product Status	RoHS Status
LP5951MFX-2.5	Texas Instruments	2.5V	150mA	5.5V	0.35V @ 150mA	55 µA	SOT-23-5	-40°C ~ 125°C	Obsolete	Non-compliant
LP5951MFX-2.5/NOPB	Texas Instruments	2.5V	150mA	5.5V	0.35V @ 150mA	55 µA	SOT-23-5	-40°C ~ 125°C	Active	ROHS3 Compliant
LP5951MF-2.5/NOPB	Texas Instruments	2.5V	150mA	5.5V	0.35V @ 150mA	55 µA	SOT-23-5	-40°C ~ 125°C	Active	ROHS3 Compliant
BU25SD2MG-MTR	Rohm Semiconductor	2.5V	200mA	6V	0.18V @ 100mA	80 µA	5-SSOP	-40°C ~ 105°C	Active	ROHS3 Compliant
MIC5306-2.5YD5-TR	Microchip Technology	2.5V	150mA	5.5V	0.2V @ 150mA	25 µA	TSOT-23-5	-40°C ~ 125°C	Active	ROHS3 Compliant
S-1135D25-M5T1U	ABLIC Inc.	2.5V	300mA	5.5V	Not specified	1 µA	SOT-23-5	-40°C ~ 85°C	Obsolete	ROHS3 Compliant
S-1312A25-M5T1U3	ABLIC Inc.	2.5V	150mA	5.5V	0.32V @ 100mA	30 µA	SOT-23-5	-40°C ~ 85°C	Active	ROHS3 Compliant
S-1312B25-M5T1U3	ABLIC Inc.	2.5V	150mA	5.5V	0.32V @ 100mA	30 µA	SOT-23-5	-40°C ~ 85°C	Active	ROHS3 Compliant
S-1312C25-M5T1U3	ABLIC Inc.	2.5V	150mA	5.5V	0.32V @ 100mA	30 µA	SOT-23-5	-40°C ~ 85°C	Active	ROHS3 Compliant
S-1312D25-M5T1U3	ABLIC Inc.	2.5V	150mA	5.5V	0.32V @ 100mA	30 µA	SOT-23-5	-40°C ~ 85°C	Active	ROHS3 Compliant
S-1313A25-M5T1U3	ABLIC Inc.	2.5V	200mA	5.5V	0.38V @ 100mA	1.35 µA	SOT-23-5	-40°C ~ 85°C	Active	ROHS3 Compliant

Engineering Selection Recommendations

Primary Recommendation — Direct Equivalent: LP5951MFX-2.5/NOPB is the direct active equivalent of the obsolete LP5951MFX-2.5. This part maintains identical electrical specifications, package type, and operating temperature range while achieving ROHS3 compliance. Selection of this part eliminates design changes and ensures functional compatibility.

Secondary Recommendation — Parametric Equivalent: LP5951MF-2.5/NOPB provides identical electrical performance with packaging variation (Cut Tape & Digi-Reel versus Tape & Reel). This part is suitable for applications where packaging format does not constrain procurement or assembly processes.

Alternative Recommendation — Enhanced Performance: MIC5306-2.5YD5-TR from Microchip Technology meets all electrical requirements with improved performance characteristics: lower dropout voltage (0.2V versus 0.35V), reduced quiescent current (25 µA versus 55 µA), and active product status with ROHS3 compliance. Package type is TSOT-23-5, which is mechanically compatible with SOT-23-5 footprints. This part is suitable for designs prioritizing power efficiency.

Alternative Recommendation — Higher Current Capability: BU25SD2MG-MTR from Rohm Semiconductor provides 200mA output current (versus 150mA), lower dropout voltage (0.18V @ 100mA), and higher input voltage rating (6V). This part is qualified to AEC-Q100 automotive standards and carries active product status with ROHS3 compliance. Package type is 5-SSOP, which requires footprint verification before selection.

ABLIC Series Alternatives: S-1312 series parts (S-1312A25-M5T1U3, S-1312B25-M5T1U3, S-1312C25-M5T1U3, S-1312D25-M5T1U3) provide 150mA output current with SOT-23-5 packaging and active product status. Operating temperature range is -40°C to 85°C, which is narrower than the original part. These parts are suitable for applications not requiring extended temperature operation above 85°C.

S-1313A25-M5T1U3 provides 200mA output current with SOT-23-5 packaging and active product status. Operating temperature range is -40°C to 85°C.

Frequently Asked Questions (FAQ)

Q: Can I use LP5951MFX-2.5/NOPB as a direct replacement for LP5951MFX-2.5?

A: Yes. LP5951MFX-2.5/NOPB is the active equivalent with identical electrical specifications, package type, and operating temperature range. The primary difference is product status (active versus obsolete) and RoHS compliance (ROHS3 versus non-compliant). No design changes are required.

Q: What is the difference between LP5951MFX-2.5/NOPB and LP5951MF-2.5/NOPB?

A: Both parts have identical electrical specifications and operating temperature range. The difference is packaging format: LP5951MFX-2.5/NOPB is supplied in Tape & Reel (TR), while LP5951MF-2.5/NOPB is supplied in Cut Tape (CT) & Digi-Reel. Selection depends on procurement and assembly requirements.

Q: Can I use MIC5306-2.5YD5-TR instead of LP5951MFX-2.5?

A: Yes, with package verification. MIC5306-2.5YD5-TR meets all electrical requirements with improved performance (lower dropout voltage and quiescent current). The package is TSOT-23-5, which is mechanically compatible with SOT-23-5 footprints. Verify PCB footprint compatibility before design release.

Q: Why does BU25SD2MG-MTR have a different package type (5-SSOP)?

A: BU25SD2MG-MTR is a higher-current alternative (200mA) with enhanced performance characteristics. The 5-SSOP package is physically different from SOT-23-5 and requires PCB footprint modification. This part is recommended only when higher current capability is required and footprint changes are acceptable.

Q: What is the operating temperature limitation of ABLIC S-1312 series parts?

A: ABLIC S-1312 series parts operate from -40°C to 85°C, which is narrower than the original LP5951MFX-2.5 range (-40°C to 125°C). These parts are suitable for applications not requiring operation above 85°C. Verify application temperature requirements before selection.

Q: Are all substitute parts RoHS compliant?

A: All active substitute parts listed carry ROHS3 compliance. The original LP5951MFX-2.5 is RoHS non-compliant. Direct equivalent LP5951MFX-2.5/NOPB achieves ROHS3 compliance while maintaining identical electrical specifications.

Q: Can I use S-1313A25-M5T1U3 for higher current applications?

A: Yes. S-1313A25-M5T1U3 provides 200mA output current (versus 150mA) with SOT-23-5 packaging and active product status. Operating temperature range is -40°C to 85°C. This part is suitable for applications requiring higher current capacity within the specified temperature range.

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