LP5951MF-1.5 Equivalent & Substitute Parts

Part Overview

The LP5951MF-1.5 is a linear voltage regulator IC from Texas Instruments, delivering a fixed 1.5V output at 150mA in a SOT-23-5 surface mount package. This part is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production support. The device provides positive fixed output configuration with integrated enable control and comprehensive protection features including overcurrent, over-temperature, and short-circuit protection.

Key Parameters

Parameter	Value
Manufacturer	Texas Instruments
Part Number	LP5951MF-1.5
Product Status	Obsolete
Output Voltage (Fixed)	1.5V
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	-40°C ~ 125°C
Control Features	Enable
Protection Features	Over Current, Over Temperature, Short Circuit
RoHS Status	RoHS non-compliant

Substitute Part Grouping Explanation

Substitute parts for the LP5951MF-1.5 are categorized based on the following critical parameters that determine functional equivalence:

Primary Substitution Criteria:

Fixed output voltage of 1.5V
Output current capability of 150mA or greater
Maximum input voltage of 5.5V or higher
SOT-23-5 package compatibility
Enable control feature
Operating temperature range of -40°C to 125°C or compatible subset

Grouping Logic:

Group 1: Direct Texas Instruments Equivalents (Active Status) LP5951MF-1.5/NOPB and LP5951MFX-1.5/NOPB are parametric equivalents with identical electrical specifications. Both are active products with RoHS3 compliance, differing only in packaging format (Tape & Reel).

Group 2: Microchip Technology Alternatives MIC5306-1.5YD5-TR provides 150mA output with improved dropout voltage (0.2V vs 0.35V) and lower quiescent current (25 µA vs 55 µA). MIC5307-1.5YD5-TR offers higher current capability (300mA) in the same package, suitable for applications requiring additional headroom.

Group 3: ABLIC Inc. Alternatives S-1312 series (A/B/C/D variants) deliver 150mA output with active product status and RoHS3 compliance. S-1135 series provides 300mA output but operates at reduced temperature range (-40°C to 85°C). All ABLIC parts use SOT-23-5 packaging.

Parameter Comparison

Part Number	Manufacturer	Status	Output (mA)	Dropout (V)	Iq (µA)	Temp Range (°C)	RoHS	Package
LP5951MF-1.5	Texas Instruments	Obsolete	150	0.35 @ 150mA	55	-40 ~ 125	Non-compliant	SOT-23-5
LP5951MF-1.5/NOPB	Texas Instruments	Active	150	0.35 @ 150mA	55	-40 ~ 125	ROHS3	SOT-23-5
LP5951MFX-1.5/NOPB	Texas Instruments	Active	150	0.35 @ 150mA	55	-40 ~ 125	ROHS3	SOT-23-5
MIC5306-1.5YD5-TR	Microchip Technology	Active	150	0.2 @ 150mA	25	-40 ~ 125	ROHS3	TSOT-23-5
MIC5307-1.5YD5-TR	Microchip Technology	Active	300	0.25 @ 300mA	30	-40 ~ 125	ROHS3	TSOT-23-5
S-1312A15-M5T1U3	ABLIC Inc.	Active	150	0.47 @ 100mA	30	-40 ~ 85	ROHS3	SOT-23-5
S-1312B15-M5T1U3	ABLIC Inc.	Active	150	0.47 @ 100mA	30	-40 ~ 85	ROHS3	SOT-23-5
S-1312C15-M5T1U3	ABLIC Inc.	Active	150	0.47 @ 100mA	30	-40 ~ 85	ROHS3	SOT-23-5
S-1312D15-M5T1U3	ABLIC Inc.	Active	150	0.47 @ 100mA	30	-40 ~ 85	ROHS3	SOT-23-5
S-1135A15-M5T1U	ABLIC Inc.	Obsolete	300	Not specified	1	-40 ~ 85	ROHS3	SOT-23-5
S-1135C15-M5T1U	ABLIC Inc.	Obsolete	300	Not specified	1	-40 ~ 85	ROHS3	SOT-23-5

Engineering Selection Recommendations

For Direct Replacement (Identical Specifications): LP5951MF-1.5/NOPB and LP5951MFX-1.5/NOPB are the primary choices. Both maintain identical electrical performance to the obsolete LP5951MF-1.5 while offering active product status and RoHS3 compliance. These parts are suitable for designs requiring no circuit modifications.

For New Designs with Enhanced Performance: MIC5306-1.5YD5-TR offers superior dropout voltage (0.2V vs 0.35V) and lower quiescent current (25 µA vs 55 µA), reducing power dissipation in battery-powered applications. MIC5307-1.5YD5-TR provides doubled output current (300mA) for applications requiring additional current margin, though this requires circuit board layout verification for thermal management.

For Active Product Status with Standard Performance: S-1312 series (variants A/B/C/D) from ABLIC Inc. provide active product status with RoHS3 compliance and 150mA output matching the original specification. These parts operate within -40°C to 85°C temperature range, suitable for most industrial and commercial applications. Higher dropout voltage (0.47V @ 100mA) must be considered in low-input-voltage designs.

Compliance Considerations: All recommended active substitutes carry RoHS3 compliance, addressing regulatory requirements for new production. The original LP5951MF-1.5 is RoHS non-compliant; migration to compliant alternatives is necessary for new designs and long-term supply chain sustainability.

Frequently Asked Questions (FAQ)

Q: Can LP5951MF-1.5/NOPB directly replace LP5951MF-1.5 without circuit changes? A: Yes. LP5951MF-1.5/NOPB is a parametric equivalent with identical electrical specifications, output voltage, current rating, dropout voltage, and package type. The only difference is packaging format (Tape & Reel vs bulk). No circuit modifications are required.

Q: What is the difference between LP5951MFX-1.5/NOPB and LP5951MF-1.5/NOPB? A: Both are parametric equivalents with identical electrical performance. The "X" designation indicates a different manufacturing process or test condition variant. Both are active products with RoHS3 compliance and suitable for direct substitution.

Q: Why does MIC5306-1.5YD5-TR have lower quiescent current than the original part? A: MIC5306 uses a different IC design architecture from Microchip Technology, resulting in 25 µA quiescent current versus 55 µA for the LP5951. This reduces standby power consumption, beneficial for battery-powered applications. All other electrical parameters remain compatible.

Q: Can MIC5307-1.5YD5-TR (300mA) be used in place of LP5951MF-1.5 (150mA)? A: Yes, MIC5307 is a functional superset with doubled output current capability. It maintains the same 1.5V output voltage, input voltage range, and SOT-23-5 package. The higher current rating provides design margin without circuit modifications, though thermal dissipation must be evaluated for the specific application.

Q: What is the temperature range limitation of S-1312 series compared to the original part? A: S-1312 series operates from -40°C to 85°C, while LP5951MF-1.5 operates to 125°C. For applications requiring full -40°C to 125°C operation, use LP5951MF-1.5/NOPB, LP5951MFX-1.5/NOPB, MIC5306-1.5YD5-TR, or MIC5307-1.5YD5-TR. S-1312 is suitable for industrial and commercial temperature ranges.

Q: Are TSOT-23-5 and SOT-23-5 packages physically compatible? A: TSOT-23-5 (Thin SOT-23-5) and SOT-23-5 (SC-74A) share identical pin configurations and footprints. Both are surface mount packages with 5 pins in the same physical layout. PCB designs using SOT-23-5 footprints accept TSOT-23-5 components without modification.

Q: Why is S-1135 series listed as obsolete if it provides 300mA output? A: S-1135A15-M5T1U and S-1135C15-M5T1U are obsolete products from ABLIC Inc., despite offering higher current capability. For new designs, use active alternatives: MIC5307-1.5YD5-TR (Microchip) or S-1312 series (ABLIC) for current production availability and long-term supply assurance.

Q: What is the impact of higher dropout voltage in S-1312 series? A: S-1312 series has 0.47V dropout at 100mA versus 0.35V for LP5951MF-1.5. In applications with tight input-to-output voltage margins, this higher dropout may reduce available headroom. Calculate minimum input voltage requirement: Vin(min) = Vout + Vdropout. For 1.5V output with 0.47V dropout, minimum input is 1.97V.

Q: Are all substitute parts RoHS3 compliant? A: All active substitute parts listed (LP5951MF-1.5/NOPB, LP5951MFX-1.5/NOPB, MIC5306-1.5YD5-TR, MIC5307-1.5YD5-TR, and S-1312 series) carry RoHS3 compliance. The original LP5951MF-1.5 is RoHS non-compliant. Migration to compliant alternatives is required for new production and regulatory adherence.

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