LP5951MF-3.3 Equivalent & Substitute Parts

Part Overview

The LP5951MF-3.3 is a linear voltage regulator IC from Texas Instruments, delivering a fixed 3.3V output at 150mA in a SOT-23-5 surface mount package. This part is designated as Last Time Buy, indicating end-of-life status. Identifying equivalent and substitute parts is essential for design continuity, inventory management, and long-term product support when the original part becomes unavailable.

Key Parameters

Parameter	Value
Manufacturer	Texas Instruments
Output Voltage (Fixed)	3.3V
Output Current	150mA
Input Voltage (Max)	5.5V
Voltage Dropout (Max)	0.35V @ 150mA
Quiescent Current	55 µA
Package Type	SOT-23-5 (SC-74A)
Operating Temperature Range	-40°C to 125°C
Control Features	Enable
Protection Features	Over Current, Over Temperature, Short Circuit
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the LP5951MF-3.3 is determined by the following critical parameters:

Primary Matching Criteria:

Fixed output voltage of 3.3V
Output current capability of 150mA or greater
Maximum input voltage of 5.5V or higher
SOT-23-5 or compatible package footprint
Surface mount technology
Operating temperature range encompassing -40°C to 125°C or compatible subset

Secondary Compatibility Factors:

Voltage dropout characteristics
Quiescent current specifications
Control and protection feature alignment
RoHS and regulatory compliance status

Substitute parts are grouped into two categories: parametric equivalents (identical electrical specifications with different packaging) and manufacturer-recommended alternatives (functionally compatible with allowable parameter variations within the specified ranges).

Parameter Comparison

Part Number	Manufacturer	Output Voltage	Output Current	Input Voltage (Max)	Dropout (Max)	Quiescent Current	Package	Temp Range	Product Status
LP5951MF-3.3	Texas Instruments	3.3V	150mA	5.5V	0.35V @ 150mA	55 µA	SOT-23-5	-40°C to 125°C	Last Time Buy
LP5951MF-3.3/NOPB	Texas Instruments	3.3V	150mA	5.5V	0.35V @ 150mA	55 µA	SOT-23-5	-40°C to 125°C	Active
LP5951MFX-3.3/NOPB	Texas Instruments	3.3V	150mA	5.5V	0.35V @ 150mA	55 µA	SOT-23-5	-40°C to 125°C	Active
MIC5365-3.3YD5-T5	Microchip Technology	3.3V	150mA	5.5V	0.31V @ 150mA	39 µA	TSOT-23-5	-40°C to 125°C	Active
MIC5365-3.3YD5-TR	Microchip Technology	3.3V	150mA	5.5V	0.31V @ 150mA	39 µA	TSOT-23-5	-40°C to 125°C	Active
S-1312A33-M5T1U3	ABLIC Inc.	3.3V	150mA	5.5V	0.27V @ 100mA	30 µA	SOT-23-5	-40°C to 85°C	Active
S-1312B33-M5T1U3	ABLIC Inc.	3.3V	150mA	5.5V	0.27V @ 100mA	30 µA	SOT-23-5	-40°C to 85°C	Active
BU33SD2MG-MTR	Rohm Semiconductor	3.3V	200mA	6V	0.15V @ 100mA	80 µA	5-SSOP	-40°C to 105°C	Active
BU33SD5WG-TR	Rohm Semiconductor	3.3V	500mA	6V	0.15V @ 100mA	80 µA	5-SSOP	-40°C to 105°C	Active
BU33UC3WG-TR	Rohm Semiconductor	3.3V	300mA	5.5V	0.22V @ 300mA	90 µA	5-SSOP	-40°C to 85°C	Not For New Designs
S-1135B33-M5T1U	ABLIC Inc.	3.3V	300mA	5.5V	Not Specified	1 µA	SOT-23-5	-40°C to 85°C	Obsolete

Engineering Selection Recommendations

Tier 1 - Direct Parametric Equivalents (Recommended for Immediate Replacement):

LP5951MF-3.3/NOPB and LP5951MFX-3.3/NOPB are direct parametric equivalents from Texas Instruments with identical electrical specifications. Both parts are Active status and maintain full compatibility with the original LP5951MF-3.3 design. The primary difference is packaging format (Tape & Reel versus Cut Tape & Digi-Reel). These are the preferred substitutes for drop-in replacement without design modification.

Tier 2 - Cross-Manufacturer Equivalents (Compatible with Verification):

MIC5365-3.3YD5-T5 and MIC5365-3.3YD5-TR from Microchip Technology meet all critical electrical parameters with improved performance characteristics (lower dropout voltage of 0.31V and reduced quiescent current of 39 µA). Both are Active status and operate across the full -40°C to 125°C temperature range. Package compatibility requires verification as TSOT-23-5 differs from SOT-23-5, though both are 5-pin surface mount packages with similar footprints.

S-1312A33-M5T1U3 and S-1312B33-M5T1U3 from ABLIC Inc. provide 150mA output current with superior dropout characteristics (0.27V @ 100mA) and lower quiescent current (30 µA). Both are Active status. Operating temperature range is limited to -40°C to 85°C, which is acceptable for applications not requiring the full 125°C upper limit.

Tier 3 - Higher Current Alternatives (For Increased Load Requirements):

BU33SD2MG-MTR (200mA), BU33SD5WG-TR (500mA), and BU33UC3WG-TR (300mA) from Rohm Semiconductor offer increased output current capability. BU33SD2MG-MTR and BU33SD5WG-TR are Active status with improved dropout voltage (0.15V @ 100mA) and support input voltage up to 6V. BU33UC3WG-TR is designated Not For New Designs and should be avoided for new applications. Package type is 5-SSOP, requiring PCB layout verification for compatibility.

Tier 4 - Obsolete Parts (Not Recommended):

S-1135B33-M5T1U (ABLIC Inc., Obsolete) and BU33UC3WG-TR (Rohm Semiconductor, Not For New Designs) should not be selected for new designs. These parts have limited availability and no long-term support commitment.

All recommended substitutes maintain RoHS3 compliance and REACH unaffected status consistent with the original part.

Frequently Asked Questions (FAQ)

Q: Can I use LP5951MF-3.3/NOPB as a direct replacement for LP5951MF-3.3?

A: Yes. LP5951MF-3.3/NOPB is a parametric equivalent with identical electrical specifications. The only difference is packaging format (Tape & Reel versus Cut Tape). No design changes are required.

Q: What is the difference between SOT-23-5 and TSOT-23-5 packages?

A: Both are 5-pin surface mount packages with similar footprints and pin configurations. TSOT-23-5 is a thin variant. PCB layout compatibility should be verified with the component datasheet, but electrical functionality is equivalent.

Q: Can I use the Rohm BU33 series parts as substitutes?

A: Yes, with package verification. BU33SD2MG-MTR and BU33SD5WG-TR are Active status with improved performance. However, they use 5-SSOP packaging instead of SOT-23-5, requiring PCB layout confirmation. BU33UC3WG-TR is Not For New Designs and should be avoided.

Q: Why does the ABLIC S-1312 series have a lower operating temperature maximum (85°C vs. 125°C)?

A: The S-1312 series is rated to 85°C maximum, which is acceptable for most applications. If your design requires operation at temperatures above 85°C, select alternatives with higher temperature ratings such as the Texas Instruments or Microchip options.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All parts listed in this reference maintain RoHS3 compliance and REACH unaffected status, consistent with regulatory requirements.

Q: What should I do if I need higher output current than 150mA?

A: The Rohm BU33SD2MG-MTR (200mA), BU33UC3WG-TR (300mA), and BU33SD5WG-TR (500mA) provide increased current capability. Verify package compatibility and thermal management requirements for your application.

Q: Is the S-1135B33-M5T1U still available?

A: S-1135B33-M5T1U is designated Obsolete and should not be selected for new designs. Use Active status alternatives such as S-1312A33-M5T1U3 or S-1312B33-M5T1U3 instead.

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