LP2951CDM-3.3R2 Equivalent & Substitute Parts

Part Overview

The LP2951CDM-3.3R2 is a linear voltage regulator IC from onsemi, delivering a fixed 3.3V output at 100mA in an 8-MSOP package. This part is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production support. The LP2951 series provides positive fixed output regulation with integrated over-current and over-temperature protection, suitable for low-power applications requiring stable 3.3V supply rails.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	3.3V
Output Current	100mA
Input Voltage (Max)	30V
Dropout Voltage (Max)	0.45V @ 100mA
Quiescent Current	120 µA
Operating Temperature Range	-40°C to 125°C
Package Type	8-MSOP (0.118", 3.00mm Width)
Protection Features	Over Current, Over Temperature

Substitute Part Grouping Explanation

Substitution for the LP2951CDM-3.3R2 is determined by the following critical parameters:

Fixed 3.3V output voltage
100mA output current capability
30V maximum input voltage rating
8-MSOP package footprint compatibility
Operating temperature range of -40°C to 125°C
Over-current and over-temperature protection

The substitute parts are grouped into two categories:

Parametric Equivalent: LP2951ACDM-3.3RG (onsemi) maintains identical electrical specifications and package type, with the primary distinction being active product status and RoHS3 compliance versus the obsolete, non-compliant original part.

Similar Alternatives: LP2951ACMM-3.3/NOPB, LP2951ACMMX-3.3/NOPB, LP2951CMM-3.3/NOPB, and LP2951CMMX-3.3/NOPB (Texas Instruments) provide functional equivalence with compatible electrical performance. These parts feature adjustable output capability (fixed at 3.3V through external resistor configuration), enable control functionality, and enhanced protection including short-circuit protection. Packaging variants differ (Cut Tape vs. Tape & Reel), and dropout voltage is specified at 0.6V @ 100mA.

Parameter Comparison

Parameter	LP2951CDM-3.3R2 (onsemi)	LP2951ACDM-3.3RG (onsemi)	LP2951ACMM-3.3/NOPB (TI)	LP2951ACMMX-3.3/NOPB (TI)	LP2951CMM-3.3/NOPB (TI)	LP2951CMMX-3.3/NOPB (TI)
Manufacturer	onsemi	onsemi	Texas Instruments	Texas Instruments	Texas Instruments	Texas Instruments
Product Status	Obsolete	Active	Active	Active	Active	Active
Output Voltage (Fixed)	3.3V	3.3V	1.235V (3.3V)	1.235V (3.3V)	1.235V (3.3V)	1.235V (3.3V)
Output Current	100mA	100mA	100mA	100mA	100mA	100mA
Input Voltage (Max)	30V	30V	30V	30V	30V	30V
Dropout Voltage (Max)	0.45V @ 100mA	0.45V @ 100mA	0.6V @ 100mA	0.6V @ 100mA	0.6V @ 100mA	0.6V @ 100mA
Quiescent Current	120 µA	120 µA	120 µA	120 µA	120 µA	120 µA
Operating Temperature	-40°C to 125°C	-40°C to 125°C	-40°C to 125°C (TJ)	-40°C to 125°C (TJ)	-40°C to 125°C (TJ)	-40°C to 125°C (TJ)
Package Type	8-MSOP	8-MSOP	8-VSSOP	8-VSSOP	8-VSSOP	8-VSSOP
Protection Features	Over Current, Over Temperature	Over Current, Over Temperature	Over Current, Over Temperature, Short Circuit	Over Current, Over Temperature, Short Circuit	Over Current, Over Temperature, Short Circuit	Over Current, Over Temperature, Short Circuit
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Packaging Option	Standard	Standard	Cut Tape (CT) & Digi-Reel®	Tape & Reel (TR)	Tape & Reel (TR)	Cut Tape (CT) & Digi-Reel®

Engineering Selection Recommendations

For Direct Replacement (Obsolete Part Mitigation): LP2951ACDM-3.3RG from onsemi is the primary recommendation. This part maintains identical electrical specifications and 8-MSOP package compatibility with the obsolete LP2951CDM-3.3R2, while offering active product status and RoHS3 compliance. No circuit modifications are required for this substitution.

For New Designs and Long-Term Availability: Texas Instruments LP2951 variants (LP2951ACMM-3.3/NOPB, LP2951ACMMX-3.3/NOPB, LP2951CMM-3.3/NOPB, LP2951CMMX-3.3/NOPB) provide active product status with enhanced protection features including short-circuit protection. These parts feature adjustable output architecture configured for 3.3V fixed output and include enable control functionality. The 8-VSSOP package is mechanically compatible with 8-MSOP footprints. Dropout voltage specification of 0.6V @ 100mA represents a 0.15V increase compared to the original part; this difference is acceptable for most applications but must be verified in power budget calculations for designs operating near minimum input voltage margins.

Compliance Consideration: All substitute parts are RoHS3 compliant and REACH unaffected, addressing regulatory requirements that the obsolete original part does not meet.

Frequently Asked Questions (FAQ)

Q: Can LP2951ACDM-3.3RG be used as a direct drop-in replacement for LP2951CDM-3.3R2? A: Yes. Both parts share identical electrical specifications (3.3V fixed output, 100mA current, 0.45V dropout @ 100mA), identical operating temperature range (-40°C to 125°C), and the same 8-MSOP package. No circuit modifications are required. The primary differences are product status (active vs. obsolete) and RoHS compliance.

Q: What is the difference between the onsemi and Texas Instruments LP2951 variants? A: The onsemi LP2951ACDM-3.3RG maintains fixed output architecture identical to the original part. Texas Instruments variants feature adjustable output capability (configured for 3.3V through external resistors), enable control functionality, and enhanced protection including short-circuit protection. Dropout voltage for TI parts is specified at 0.6V @ 100mA versus 0.45V for onsemi parts.

Q: Are the 8-MSOP and 8-VSSOP packages footprint compatible? A: Both packages are 8-pin surface-mount packages with 0.118" (3.00mm) width. While pin counts and pitch are identical, physical dimensions and lead configurations differ slightly. PCB layout verification is required before committing to production. Consult package datasheets for precise dimensional specifications.

Q: What is the impact of the 0.15V higher dropout voltage in Texas Instruments parts? A: The TI variants specify 0.6V dropout @ 100mA compared to 0.45V for onsemi parts. This 0.15V difference affects minimum input voltage requirements. For applications with tight input voltage margins, verify that the higher dropout voltage does not compromise system performance. Most general-purpose 3.3V supply applications tolerate this specification difference.

Q: Which substitute part offers the best long-term availability? A: Texas Instruments LP2951 variants (LP2951CMM-3.3/NOPB and LP2951CMMX-3.3/NOPB) show the highest inventory levels (5950 and 2700 units respectively) and active product status, indicating strong long-term supply continuity. These parts are recommended for new designs requiring extended production lifecycles.

Q: Do the substitute parts require circuit modifications? A: LP2951ACDM-3.3RG requires no modifications. Texas Instruments variants feature adjustable output architecture but are factory-configured for 3.3V fixed output through internal or external resistor networks. Verify output voltage configuration in the specific datasheet variant selected. Enable control functionality in TI parts is optional and does not require circuit changes if left unconnected.

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